java英文笔试题
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1.Which of the following lines will compile without warning or error.答案(5)1) float f=1.3;2) char c="a";3) byte b=257;4) boolean b=null;5) int i=10;2. What will happen if you try to compile and run the following codepublic class MyClass {public static void main(String arguments[]) {amethod(arguments);}public void amethod(String[] arguments) {System.out.println(arguments);System.out.println(arguments[1]);}}答案(1)1) error Can't make static reference to void amethod.2) error method main not correct3) error array must include parameter4) amethod must be declared with String3. Which of the following will compile without error答案(23)1) import java.awt.*;package Mypackage;class Myclass {}2) package MyPackage;import java.awt.*;class MyClass{}3) /*This is a comment */package MyPackage;import java.awt.*;class MyClass{}4. What will be printed out if this code is run with the following command line? java myprog good morningpublic class myprog{public static void main(String argv[]){System.out.println(argv[2]);}}答案(4)1) myprog2) good3) morning4) Exception raised:"ng.ArrayIndexOutOfBoundsException: 2"5. What will happen when you compile and run the following code? public class MyClass{static int i;public static void main(String argv[]){System.out.println(i);}}答案(4)1) Error Variable i may not have been initialized2) null3) 14) 06. What will happen if you try to compile and run the following code? public class Q {public static void main(String argv[]){int anar[]=new int[]{1,2,3};System.out.println(anar[1]);}}答案(3)1) 12) Error anar is referenced before it is initialized3) 24) Error: size of array must be defined7. What will happen if you try to compile and run the following code? public class Q {public static void main(String argv[]){int anar[]=new int[5];System.out.println(anar[0]);}}答案(3)1) Error: anar is referenced before it is initialized2) null3) 04) 58. What will be the result of attempting to compile and run the following code?答案(3)abstract class MineBase {abstract void amethod();static int i;}public class Mine extends MineBase {public static void main(String argv[]){int[] ar=new int[5];for(i=0;i < ar.length;i++)System.out.println(ar[i]);}}1) a sequence of 5 0's will be printed2) Error: ar is used before it is initialized3) Error Mine must be declared abstract4) IndexOutOfBoundes Error9. What will be printed out if you attempt to compile and run the following code ? int i=1;switch (i) {case 0:System.out.println("zero");break;case 1:System.out.println("one");case 2:System.out.println("two");default:System.out.println("default");}答案(3)1) one2) one, default3) one, two, default4) default10. Which of the following lines of code will compile without error答案(23)1) int i=0;if(i) {System.out.println("Hello");}2) boolean b=true;boolean b2=true;if(b==b2) {System.out.println("So true");}3) int i=1;int j=2;if(i==1|| j==2)System.out.println("OK");4) int i=1;int j=2;if(i==1 &| j==2)System.out.println("OK");11. What will be output if you try to compile and run the following code, but there is no file called Hello.txt in the current directory?.import java.io.*;public class Mine{public static void main(String argv[]){Mine m=new Mine();System.out.println(m.amethod());}public int amethod(){try{FileInputStream dis=new FileInputStream("Hello.txt");}catch (FileNotFoundException fne){System.out.println("No such file found");return -1;}catch(IOException ioe){}finally{System.out.println("Doing finally");}return 0;}}答案(3)1) No such file found2 No such file found ,-13) No such file found, Doing finally, -14) 012.Which of the following statements are true?答案(1)1) Methods cannot be overriden to be more private2) static methods cannot be overloaded3) private methods cannot be overloaded4) An overloaded method cannot throw exceptions not checked in the base class13.What will happen if you attempt to compile and run the following code?答案(3)class Base {}class Sub extends Base {}class Sub2 extends Base {}public class CEx{public static void main(String argv[]){Base b=new Base();Sub s=(Sub) b;}}1) Compile and run without error2) Compile time Exception3) Runtime Exception14.Which of the following statements are true?答案(123)1) System.out.println( -1 >>> 2);will output a result larger than 102) System.out.println( -1 >>> 2); will output a positive number3) System.out.println( 2 >> 1); will output the number 14) System.out.println( 1 <<< 2); will output the number 415.What will happen when you attempt to compile and run the following code? public class Tux extends Thread{static String sName = "vandeleur";public static void main(String argv[]){Tux t = new Tux();t.piggy(sName);System.out.println(sName);}public void piggy(String sName){sName = sName + " wiggy";start();}public void run(){for(int i=0;i < 4; i++){sName = sName + " " + i;}}}答案(4)1) Compile time error2) Compilation and output of "vandeleur wiggy"3) Compilation and output of "vandeleur wiggy 0 1 2 3"4) Compilation and output of either "vandeleur", "vandeleur 0", "vandeleur 0 1" "vandaleur 0 1 2" or "vandaleur 0 1 2 3"16.What will be displayed when you attempt to compile and run the following code//Code startimport java.awt.*;public class Butt extends Frame{public static void main(String argv[]){Butt MyBut=new Butt();}Butt(){Button HelloBut=new Button("Hello");Button ByeBut=new Button("Bye");add(HelloBut);add(ByeBut);setSize(300,300);setVisible(true);}}//Code end答案(3)1) Two buttons side by side occupying all of the frame, Hello on the left and Bye on the right2) One button occupying the entire frame saying Hello3) One button occupying the entire frame saying Bye4) Two buttons at the top of the frame one saying Hello the other saying Bye17.What will be output by the following code?public class MyFor{public static void main(String argv[]){int i;int j;outer:for (i=1;i <3;i++)inner:for(j=1; j<3; j++) {if (j==2)continue outer;System.out.println("Value for i=" + i + " Value for j=" +j); }}}答案(12)1) Value for i=1 Value for j=12) Value for i=2 Value for j=13) Value for i=2 Value for j=24) Value for i=3 Value for j=118.Which statement is true of the following code?public class Agg{public static void main(String argv[]){Agg a = new Agg();a.go();}public void go(){DSRoss ds1 = new DSRoss("one");ds1.start();}}class DSRoss extends Thread{private String sTname="";DSRoss(String s){sTname = s;}public void run(){notwait();System.out.println("finished");}public void notwait(){while(true){try{System.out.println("waiting");}catch(InterruptedException ie){}System.out.println(sTname);notifyAll();}}}答案(4)1) It will cause a compile time error2) Compilation and output of "waiting"3) Compilation and output of "waiting" followed by "finished"4) Runtime error, an exception will be thrown19.Which of the following methods can be legally inserted in place of the comment //Method Here ?class Base{public void amethod(int i) { }}public class Scope extends Base{public static void main(String argv[]){}//Method Here}答案(23)1) void amethod(int i) throws Exception {}2) void amethod(long i)throws Exception {}3) void amethod(long i){}4) public void amethod(int i) throws Exception {}20.You have created a simple Frame and overridden the paint method as followspublic void paint(Graphics g){g.drawString("Dolly",50,10);}What will be the result when you attempt to compile and run the program?答案(3)1) The string "Dolly" will be displayed at the centre of the frame2) An error at compilation complaining at the signature of the paint method3) The lower part of the word Dolly will be seen at the top of the frame, with the top hidden.4) The string "Dolly" will be shown at the bottom of the frame.21.What will be the result when you attempt to compile this program?public class Rand{public static void main(String argv[]){iRand = Math.random();System.out.println(iRand);}}答案(1)1) Compile time error referring to a cast problem2) A random number between 1 and 103) A random number between 0 and 14) A compile time error about random being an unrecognised method22.Given the following codeimport java.io.*;public class Th{public static void main(String argv[]){Th t = new Th();t.amethod();}public void amethod(){try{ioCall();}catch(IOException ioe){}}}What code would be most likely for the body of the ioCall method答案(1)1) public void ioCall ()throws IOException{DataInputStream din = new DataInputStream(System.in);din.readChar();}2) public void ioCall ()throw IOException{DataInputStream din = new DataInputStream(System.in);din.readChar();}3) public void ioCall (){DataInputStream din = new DataInputStream(System.in);din.readChar();}4) public void ioCall throws IOException(){DataInputStream din = new DataInputStream(System.in);din.readChar();}23.What will happen when you compile and run the following code?public class Scope{private int i;public static void main(String argv[]){Scope s = new Scope();s.amethod();}//End of mainpublic static void amethod(){System.out.println(i);}//end of amethod}//End of class答案(3)1) A value of 0 will be printed out2) Nothing will be printed out3) A compile time error4) A compile time error complaining of the scope of the variable i24.You want to lay out a set of buttons horizontally but with more space between the first button and the rest. You are going to use the GridBagLayout manager to control the way the buttons are set out. How will you modify the way the GridBagLayout acts in order to change the spacing around the first button?答案(2)1) Create an instance of the GridBagConstraints class, call the weightx() method and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.2) Create an instance of the GridBagConstraints class, set the weightx field and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.3) Create an instance of the GridBagLayout class, set the weightx field and then call the setConstraints method of the GridBagLayoutClass with the component as a parameter.4) Create an instance of the GridBagLayout class, call the setWeightx() method and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.25.Which of the following can you perform using the File class?答案(23)1) Change the current directory2) Return the name of the parent directory3) Delete a file4) Find if a file contains text or binary information26.Which statement is true of the following code?public class Rpcraven{public static void main(String argv[]){Pmcraven pm1 = new Pmcraven("One");pm1.run();Pmcraven pm2 = new Pmcraven("Two");pm2.run();}}class Pmcraven extends Thread{private String sTname="";Pmcraven(String s){sTname = s;}public void run(){for(int i =0; i < 2 ; i++){try{sleep(1000);}catch(InterruptedException e){}yield();System.out.println(sTname);}}}答案(2)1) Compile time error, class Rpcraven does not import ng.Thread2) Output of One One Two Two3) Output of One Two One Two4) Compilation but no output at runtime27.You are concerned that your program may attempt to use more memory than is available. To avoid this situation you want to ensure that the Java Virtual Machine will run its garbage collection just before you start a complex routine. What can you do to be certain that garbage collection will run when you want .答案(1)1) You cannot be certain when garbage collection will run2) Use the Runtime.gc() method to force garbage collection3) Ensure that all the variables you require to be garbage collected are set to null4) Use the System.gc() method to force garbage collection28、Which statements about the garbage collection are true?答案(2)1. The program developer must create a thread to be responsible for free the memory.2. The garbage collection will check for and free memory no longer needed.3. The garbage collection allow the program developer to explicity and immediately free the memory.4. The garbage collection can free the memory used java object at expect time.29.You have these files in the same directory. What will happen when you attempt to compile and run Class1.java if you have not already compiled Base.java//Base.javapackage Base;class Base{protected void amethod(){System.out.println("amethod");}//End of amethod}//End of class basepackage Class1;//Class1.javapublic class Class1 extends Base{public static void main(String argv[]){Base b = new Base();b.amethod();}//End of main}//End of Class1答案(4)1) Compile Error: Methods in Base not found2) Compile Error: Unable to access protected method in base class3) Compilation followed by the output "amethod"4)Compile error: Superclass Class1.Base of class Class1.Class1 not found30.What will happen when you attempt to compile and run the following codeclass Base{private void amethod(int iBase){System.out.println("Base.amethod");}}class Over extends Base{public static void main(String argv[]){Over o = new Over();int iBase=0;o.amethod(iBase);}public void amethod(int iOver){System.out.println("Over.amethod");}}答案(4)1) Compile time error complaining that Base.amethod is private2) Runtime error complaining that Base.amethod is private3) Output of "Base.amethod"4) Output of "Over.amethod"一个袋子中有100个黑球,100个白球,每次从中取出两个球,然后放回一个球,如果取出两个球颜色相同,则放入一个黑球,如果取出一百一黑,则放入一个白球,请问到最后袋中剩下的球的颜色:1)黑球2)白球3)不一定。
正式应聘的JAVA笔试题和答案一:选择题1:List, Set, Map是否继承自Collection接口A:都是,B 都不是 C:List, Set 是 D:Set, Map 是正确答案 C2:下面描述哪个是正确的A:构造器Constructor可被overrideB:可以继承String类C:try {}里有一个return语句,那么紧跟在这个try后的finally {}里的code不会被执行D:两个对象值相同(x.equals(y) == true),那么也有相同的hash code正确答案 D3 abstract的method是否可同时是static,是否可同时是native,是否可同时是synchronized A:都能 B:都不能 C:可以为static D:可以为native正确答案 A4:下面的程序中,temp的最终值是什么?long temo=(int)3.9;temp%=2;A: 0 B :1 C :2 D : 3正确答案 B5、请在以下选项中选出非基本数据类型的选项 ( )A: int B:byte C: boolean D:String正确答案 D6、阅读下面代码段, 给出以下代码的输出结果public class Test{public static void main(String args[]){String str1 = "abc";String str = "abc;String str2 = new String("abc");System.out.println(str1 == str2);System.out.println(str1.equals(str2));System.out.println(str == str1);}}A:true,true,true B:true,false,true C:true,true,false D:false,true,true正确答案 D7、阅读下面代码段, 给出以下代码的输出结果:int i=1;switch (i) {case 0:System.out.println("zero");break;case 1:System.out.println("one");case 2:System.out.println("two");default:System.out.println("default");}A: B::D:default 正确答案 C8、阅读下面代码段, 给出以下代码的输出结果public class MyClass{static int i;public static void main(String argv[]){System.out.println(i);}}A: Error Variable i may not have been initialized B:null C:D:0 正确答案 D9、阅读下面代码段, 给出以下代码的输出结果:class A{static{System.out.print( “A1”);}public A(){System.out.print( “A2”);}}class B extends A{static{System.out.print( “B1”);}public B(){System.out.print( “B2”);}}public class Hello{public static void main(String[] args){A ab = new B();ab = new B();}}A:A1B1A2B2B1B2 B:A1B1A2B2A2B2 C:A1B1A2B2B1B2 D:A1A2B1B2A2B2正确答案 B10、阅读下面代码段, 给出以下代码的输出结果public class TestData {public String getValue () {String value = "";try{value = "test1";return value;}catch(Exception e){e.printStackTrace();}finally{value = "test2";}return value;}public static void main(String args[]){ TestData test = new TestData();String a = test.getValue();System.out.println(a);}}A.test1B.test2C.nullD.””正确答案 A二、改错题,如果有错误,请指出并修正。
JAVA英文笔试题JAVA英文笔试题1.what is oracle.2.what is major differenece oracle8i and oracle9i.4.tell me some thing ur self.5.please tell me about oops.6.what is single inheritance.7.what is multiple inheritance.8.can java support multiple inheritance.9.what is interface.10.what is differenec between abstract class and interface.11.how to u prove that abstrace class cannot instantiate directly.12.what is differenece between string and stringbuffer.13.what is immutable14.how to write a program using sort program.15 how to write a program using unsort program.16.what is legacy.17.what is legacy api18.what is legacy interface.19.what is main difference hashmap and hastable20.what is main difference between arraylist and vector.1. Oracle is an RDBMS product with DDL and DML from a company called Oracle Inc.2. Difference between 8i and 9i is given in the Oracle site3. Question not available4. Something5. oops is Object Oriented Programming6.what is single inheritance.ans:one class is inherited by only other one class7.what is multiple inheritance.ans:One class inheriting more than one class at atime8.can java support multiple inheritance.ans:No9.what is interface.ans:Interface has only method declarations but no defn10.what is differenec between abstract class and interface.ans:In abstract class some methods may contain definition,but in interface every method should be abstract11.how to u prove that abstrace class cannot instantiate directly.ans:As they dont have constructor they cant be instantiated12.what is differenece between string and stringbuffer.ans:Strings are immutable where as string buffer can be modified。
Q1. How could Java classes direct program messages to the system console, but error messages, say to a file?.Java中如何将程序信息导航到系统的console,而把错误信息放入到一个file 中?The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output could be re-directed:Stream st = new Stream(new FileOutputStream("output.txt"));System.setErr(st); System.setOut(st);系统有一个展现标准输出的out变量,以及一个负责标准错误设置的err变量,默认情况下这两个变量都指向系统的console,这就是标准输出如何能被改变方向(就是改变信息的输出位置)。
* Q2. What's the difference between an interface and an abstract class?抽象类和接口的区别:A. An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implement multiple interfaces in your class.抽象类中可能会含有带有方法体的一般方法,而这在接口中是不允许的。
Read the questions carefullyI have tried to make the questions unambiguous (the meaning should be obvious), but make sure you have read what I have written not what you think I might have written. Thus if it says "Classes can be declared with the private modifier ", it means It is possible to declare a class with the private modifier and not that all classes in all situations can be declared as private. Each question may have one or more correct Answers.QuestionsQuestion 1)Which of the following lines will compile without warning or error.1) float f=1.3;2) char c="a";3) byte b=257;4) boolean b=null;5) int i=10;Question 2)What will happen if you try to compile and run the following codepublic class MyClass {public static void main(String arguments[]) {amethod(arguments);}public void amethod(String[] arguments) {System.out.println(arguments);System.out.println(arguments[1]);}}1) error Can't make static reference to void amethod.2) error method main not correct3) error array must include parameter4) amethod must be declared with StringBecause main is defined as static you need to create an instance of the class in order to call any non-static methods.--------------------------------------------------------------------------------Question 3)Which of the following will compile without error要先出现package1) import java.awt.*;package Mypackage;class Myclass {}2) package MyPackage;import java.awt.*;class MyClass{}3) /*This is a comment */package MyPackage;import java.awt.*;class MyClass{}--------------------------------------------------------------------------------Question 4)A byte can be of what size1) -128 to 1272) (-2 power 8 )-1 to 2 power 83) -255 to 2564)depends on the particular implementation of the Java Virtual machine--------------------------------------------------------------------------------Question 5)What will be printed out if this code is run with the following command line?Java myprog good morning;public class myprog{public static void main(String argv[]){System.out.println(argv[2]);}}1) myprog2) good3) morning4) Exception raised: "ng.ArrayIndexOutOfBoundsException: 2" --------------------------------------------------------------------------------Question 6)Which of the following are keywords or reserved (预定义)words in Java?1) if2) then3) goto4) while5) case--------------------------------------------------------------------------------Question 7)Which of the following are legal identifiers(标识符)1) 2variable2) variable23) _whatavariable4) _3_5) $anothervar6) #myvar--------------------------------------------------------------------------------Question 8)What will happen when you compile and run the following code?public class MyClass{static int i;public static void main(String argv[]){System.out.println(i);}}局部变量(在函数内部)必须先初始化,类级别的可以不初始化Class level variables are always initialised to default values. In the case of an int this will be 0. Method level variables are not given default values and if you attempt to use one before it has been initialised it will cause theError Variable i may not have been initialized1) Error Variable i may not have been initialized2) null3) 14) 0--------------------------------------------------------------------------------Question 9)What will happen if you try to compile and run the following code?public class Q {public static void main(String argv[]){int anar[]=new int[]{1,2,3};System.out.println(anar[1]);}}1) 12) Error anar is referenced before it is initialized3) 24) Error: size of array must be defined-------------------------------------------------------------------------------- Question 10)What will happen if you try to compile and run the following code?public class Q {public static void main(String argv[]){int anar[]=new int[5];System.out.println(anar[0]);}}1) Error: anar is referenced before it is initialized2) null3) 04) 5-------------------------------------------------------------------------------- Question 11)What will be the result of attempting to compile and run the following code?abstract class MineBase {abstract void amethod();static int i;}public class Mine extends MineBase {public static void main(String argv[]){int[] ar=new int[5];for(i=0;i < ar.length;i++)System.out.println(ar[i]);}}Any class derived from an abstract class must either define all of the abstract methods or be declared abstract itself.1) a sequence of 5 0's will be printed2) Error: ar is used before it is initialized3) Error Mine must be declared abstract4) IndexOutOfBoundes Error--------------------------------------------------------------------------------Question 12)What will be printed out if you attempt to compile and run the following code ?int i=1;switch (i) {case 0: System.out.println("zero");break;case 1: System.out.println("one");case 2: System.out.println("two");default: System.out.println("default");}1) one2) one, default3) one, two, default4) default--------------------------------------------------------------------------------Question 13)What will be printed out if you attempt to compile and run the following code?int i=9;switch (i) {default: System.out.println("default");case 0: System.out.println("zero");break;case 1: System.out.println("one");case 2: System.out.println("two");}1) default2) default, zero3) error default clause not defined4) no output displayed--------------------------------------------------------------------------------Question 14)Which of the following lines of code will compile without error1) int i=0;if(i) {System.out.println("Hello");}2) boolean b=true;boolean b2=true;if(b==b2) {System.out.println("So true");}3) int i=1;int j=2;if(i==1|| j==2) System.out.println("OK");4) int i=1;int j=2;if(i==1 &| j==2) System.out.println("OK");--------------------------------------------------------------------------------Question 15)What will be output if you try to compile and run the following code, but there is no file called Hello.txt in the current directory?.import java.io.*;public class Mine {public static void main(String argv[]){Mine m=new Mine();System.out.println(m.amethod());}public int amethod() {try {FileInputStream dis=new FileInputStream("Hello.txt");}catch (FileNotFoundException fne) {System.out.println("No such file found");return -1;}catch(IOException ioe) { }finally{System.out.println("Doing finally");}return 0;}}1) No such file found2 No such file found ,-13) No such file found, Doing finally, -14) 0--------------------------------------------------------------------------------Question 16)Which of the following statements are true?1) Methods cannot be overriden to be more private2) static methods cannot be overloadedStatic methods cannot be overriden but they can be overloaded3) private methods cannot be overloaded4) An overloaded method cannot throw exceptions not checked in the base class--------------------------------------------------------------------------------Question 17)What will happen if you attempt to compile and run the following code?class Base {}class Sub extends Base {}class Sub2 extends Base {}public class CEx{public static void main(String argv[]){Base b=new Base();Sub s=(Sub) b;}}1) Compile and run without error2) Compile time Exception3) Runtime Exception--------------------------------------------------------------------------------Question 18)Which of the following statements are true?1) System.out.println( -1 >>> 2);will output a result larger than 10 无符号右移2) System.out.println( -1 >> 2); will output a positive number 输出-13) System.out.println( 2 >> 1); will output the number 14) System.out.println( 1 <<< 2); will output the number 4--------------------------------------------------------------------------------Question 19)What will happen when you attempt to compile and run the following code?public class Tux extends Thread{static String sName = "vandeleur";public static void main(String argv[]){Tux t = new Tux();t.piggy(sName);System.out.println(sName);}public void piggy(String sName){sName = sName + " wiggy";start();}public void run(){for(int i=0;i < 4; i++){sName = sName + " " + i;}}}1) Compile time error2) Compilation and output of "vandeleur wiggy"3) Compilation and output of "vandeleur wiggy 0 1 2 3"4) Compilation and output of either "vandeleur", "vandeleur 0", "vandeleur 0 1" "vandaleur 0 1 2" or "vandaleur 0 1 2 3"--------------------------------------------------------------------------------Question 20)What will be displayed when you attempt to compile and run the following code//Code startimport java.awt.*;public class Butt extends Frame{public static void main(String argv[]){Butt MyBut=new Butt();}Butt(){Button HelloBut=new Button("Hello");Button ByeBut=new Button("Bye");add(HelloBut);add(ByeBut);setSize(300,300);setVisible(true); }}//Code end1) Two buttons side by side occupying all of the frame, Hello on the left and Bye on the right2) One button occupying the entire frame saying Hello3) One button occupying the entire frame saying Bye4) Two buttons at the top of the frame one saying Hello the other saying Bye--------------------------------------------------------------------------------Question 21)What will be output by the following code?public class MyFor{public static void main(String argv[]){int i;int j;outer: for (i=1;i <3;i++)inner: for(j=1; j<3; j++) {if (j==2) continue outer;System.out.println("Value for i=" + i + " Value for j=" +j);}}}1) Value for i=1 Value for j=12) Value for i=2 Value for j=13) Value for i=2 Value for j=24) Value for i=3 Value for j=1--------------------------------------------------------------------------------Question 22)Which statement is true of the following code?public class Agg{public static void main(String argv[]){Agg a = new Agg();a.go();}public void go(){DSRoss ds1 = new DSRoss("one");ds1.start();}}class DSRoss extends Thread{private String sTname="";DSRoss(String s){sTname = s;}public void run(){notwait();System.out.println("finished");}public void notwait(){while(true){try{System.out.println("waiting");wait();}catch(InterruptedException ie){}System.out.println(sTname);notifyAll();}} }1) It will cause a compile time error2) Compilation and output of "waiting"3) Compilation and output of "waiting" followed by "finished"4) Runtime error, an exception will be thrown--------------------------------------------------------------------------------Question 23)Which of the following methods can be legally inserted in place of the comment //Method Here ?class Base{public void amethod(int i) { }}public class Scope extends Base{public static void main(String argv[]){ }//Method Here}1) void amethod(int i) throws Exception {}2) void amethod(long i)throws Exception {}3) void amethod(long i){}4) public void amethod(int i) throws Exception {}--------------------------------------------------------------------------------Question 24)Which of the following will output -4.01) System.out.println(Math.floor(-4.7));2) System.out.println(Math.round(-4.7));3) System.out.println(Math.ceil(-4.7));4) System.out.println(Math.min(-4.7));Options 1 and 2 will produce -5 and option 4 will not compile because the min method requires 2 parameters.--------------------------------------------------------------------------------Question 25)What will happen if you attempt to compile and run the following code?Integer ten=new Integer(10);Long nine=new Long (9);System.out.println(ten + nine);int i=1;System.out.println(i + ten);1) 19 followed by 202) 19 followed by 113) Compile time error4) 10 followed by 1--------------------------------------------------------------------------------Question 26)If you run the code below, what gets printed out?String s=new String("Bicycle");int iBegin=1;char iEnd=3;System.out.println(s.substring(iBegin,iEnd));1) Bic2) ic3) icy4) error: no method matching substring(int,char)--------------------------------------------------------------------------------Question 27)If you wanted to find out where the position of the letter v (ie return 2) in the string s containing "Java", which of the following could you use?1) mid(2,s);2) charAt(2);3) s.indexOf('v');4) indexOf(s,'v');--------------------------------------------------------------------------------Question 28)Given the following declarationsString s1=new String("Hello");String s2=new String("there");String s3=new String();Which of the following are legal operations?1) s3=s1 + s2;2) s3=s1-s2;3) s3=s1 & s2;4) s3=s1 && s2--------------------------------------------------------------------------------Question 29)What is the result of the following operation?System.out.println(4 | 3); 1000111111) 62) 03) 14) 7--------------------------------------------------------------------------------Question 30)public class MyClass1 {public static void main(String argv[]){ }/*Modifier at XX */class MyInner {}}What modifiers would be legal at XX in the above code?1) public2) private3) static4) friend-------------------------------------------------------------------------------- Question 31)What will happen when you attempt to compile and run the following code?public class Holt extends Thread{private String sThreadName;public static void main(String argv[]){Holt h = new Holt();h.go();}Holt(){}Holt(String s){sThreadName = s;}public String getThreadName(){return sThreadName;}public void go(){Holt first = new Holt("first");first.start();Holt second = new Holt("second");second.start();}public void start(){for(int i = 0; i < 2; i ++){System.out.println(getThreadName()+i);try{Thread.sleep(100);}catch(InterruptedExceptione){System.out.println(e.getMessage());} } }}1) Compile time error2) Output of first0, second0, first0, second13) Output of first0, first1, second0, second14) Runtime error--------------------------------------------------------------------------------Question 32)An Applet has its Layout Manager set to the default of FlowLayout. What code would be correct to change to another Layout Manager.1) setLayoutManager(new GridLayout());2) setLayout(new GridLayout(2,2));3) setGridLayout(2,2);4) setBorderLayout();--------------------------------------------------------------------------------Question 33)What will happen when you attempt to compile and run the following code?.class Background implements Runnable{int i=0;public int r un(){while(true){i++;System.out.println("i="+i);} //End whilereturn 1;}//End run}//End class1) It will compile and the run method will print out the increasing value of i.2) It will compile and calling start will print out the increasing value of i.3) The code will cause an error at compile time.4) Compilation will cause an error because while cannot take a parameter of true.--------------------------------------------------------------------------------Question 34)Which of the following statements about this code are true?public class Morecombe{public static void main(String argv[]){Morecombe m = new Morecombe();m.go(new Turing(){});}public void go(Turing t){t.start();}}class Turing extends Thread{public void run(){for(int i =0; i < 2; i++){System.out.println(i); }}}1) Compilation error due to malformed parameter to go method2) Compilation error, class Turing has no start method3) Compilation and output of 0 followed by 14) Compilation but runtime error--------------------------------------------------------------------------------Question 35)What will be the result when you attempt to compile and run the following code?.public class Conv{public static void main(String argv[]){Conv c=new Conv();String s=new String("ello");c.amethod(s);}public void amethod(String s){char c='H';c+=s;System.out.println(c);}}1) Compilation and output the string "Hello"2) Compilation and output the string "ello"3) Compilation and output the string elloH4) Compile time error--------------------------------------------------------------------------------Question 36)Given the following code, what test would you need to put in place of the comment line? //place test hereto result in an output of the string Equalpublic class EqTest{public static void main(String argv[]){EqTest e=new EqTest();}EqTest(){String s="Java";String s2="java";//place test here {System.out.println("Equal");}else{System.out.println("Not equal");}}}1) if(s==s2)2) if(s.equals(s2)3) if(s.equalsIgnoreCase(s2))4)if(s.noCaseMatch(s2))--------------------------------------------------------------------------------Question 37)Given the following codeimport java.awt.*;public class SetF extends Frame{public static void main(String argv[]){SetF s=new SetF();s.setSize(300,200);s.setVisible(true);}}How could you set the frame surface color to pink1)s.setBackground(Color.pink);2)s.setColor(PINK);3)s.Background(pink);4)s.color=Color.pink--------------------------------------------------------------------------------Question 38)How can you change the current working directory using an instance of the File class called FileName?1) FileName.chdir("DirName")2) FileName.cd("DirName")3) FileName.cwd("DirName")4) The File class does not support directly changing the current directory.--------------------------------------------------------------------------------Question 39)If you create a TextField with a constructor to set it to occupy 5 columns, what difference will it make if you use it with a proportional font (ie Times Roman) or a fixed pitch typewriter style font (Courier).1)With a fixed font you will see 5 characters, with a proportional it will depend on the width of the characters2)With a fixed font you will see 5 characters,with a proportional it will cause the field to expand to fit the text3)The columns setting does not affect the number of characters displayed4)Both will show exactly 5 characters--------------------------------------------------------------------------------Question 40)Given the following code how could you invoke the Base constructor that will print out the string "base constructor";class Base{Base(int i){System.out.println("base constructor"); }Base(){ }}public class Sup extends Base{public static void main(String argv[]){Sup s= new Sup();//One }Sup() { //Two }public void derived() { //Three }}1) On the line After //One put Base(10);2) On the line After //One put super(10);3) On the line After //Two put super(10);4) On the line After //Three put super(10);--------------------------------------------------------------------------------Question 41)Given the following code what will be output?public class Pass{ static int j=20;public static void main(String argv[]){ int i=10; Pass p = new Pass(); p.amethod(i);System.out.println(i); System.out.println(j); }public void amethod(int x){ x=x*2; j=j*2; }}1) Error: amethod parameter does not match variable2) 20 and 403) 10 and 404) 10, and 20--------------------------------------------------------------------------------Question 42)What code placed after the comment //For loop would result in the population of every element of the array ia[] with a value from variable i.?public class Lin{ public static void main(String argv[]){ Lin l = new Lin(); l.amethod(); }public void amethod(){ int ia[] = new int[4]; //Start For loop{ ia[i]=i; System.out.println(ia[i]);}}}1) for(int i=0; i < ia.length() -1; i++)2) for (int i=0; i< ia.length(); i++)3) for(int i=1; i < 4; i++)4) for(int i=0; i< ia.length;i++)--------------------------------------------------------------------------------Question 43)What will be the result when you try to compile and run the following code?private class Base{Base(){int i = 100;System.out.println(i);}}public class Pri extends Base{static int i = 200;public static void main(String argv[]){Pri p = new Pri();System.out.println(i);}}1) Error at compile time2) 2003) 100 followed by 2004) 100--------------------------------------------------------------------------------Question 44)What will the following code print out?public class Oct{public static void main(String argv[]){ Oct o = new Oct(); o.amethod(); }public void amethod(){int oi= 012; System.out.println(oi);}}1)122)0123)10 8*1 + 8^0 * 2 = 104)10.0--------------------------------------------------------------------------------Question 45)You need to create a class that will store unique object elements. You do not need to sort these elements but they must be unique.What interface might be most suitable to meet this need?1)Set (集合)2)List3)Map4)Vector--------------------------------------------------------------------------------Question 46)Which of the following will successfully create an instance of the Vector class and add an element?1) Vector v=new Vector(99);v[1]=99;2) Vector v=new Vector();v.addElement(99);3) Vector v=new Vector();v.add(99);4 Vector v=new Vector(100);v.addElement("99");--------------------------------------------------------------------------------Question 47)You have created a simple Frame and overridden the paint method as followspublic void paint(Graphics g){g.drawString("Dolly",50,10);}What will be the result when you attempt to compile and run the program?1) The string "Dolly" will be displayed at the centre of the frame2) An error at compilation complaining at the signature of the paint method3) The lower part of the word Dolly will be seen at the top of the frame, with the top hidden.4) The string "Dolly" will be shown at the bottom of the frame.--------------------------------------------------------------------------------Question 48)Given the following codeimport java.io.*;public class Th{public static void main(String argv[]){Th t = new Th();t.amethod(); }public void amethod(){try{ioCall();}catch(IOException ioe){}}}What code would be most likely for the body of the ioCall method1) public void ioCall ()throws IOException{DataInputStream din = new DataInputStream(System.in);din.readChar(); }2) public void ioCall ()throw IOException{DataInputStream din = new DataInputStream(System.in);din.readChar();}3) public void ioCall (){DataInputStream din = new DataInputStream(System.in);din.readChar(); }4)public void ioCall throws IOException(){DataInputStream din = new DataInputStream(System.in);din.readChar(); }--------------------------------------------------------------------------------Question 49)Which of the following can you perform using the File class?1) Change the current directory2) Return the name of the parent directory3) Access a random file4) Find if a file contains text or binary information--------------------------------------------------------------------------------Question 50)You are using the GridBagLayout manager to place a series of buttons on a Frame. You want to make the size of one of the buttons bigger than the text it contains. Which of the following will allow you to do that?1) The GridBagLayout manager does not allow you to do this2) The setFill method of the GridBagLayout class3) The setFill method of the GridBagConstraints class4) The fill field of the GridBagConstraints class--------------------------------------------------------------------------------。
Java笔试题常见英语What will be the output when you compile and execute the following program?当执行以下程序时会输出什么?output 输出compile 编译(动词)compilation(名词)execute 执行(动词)execution(名词)Runtime error. Incompatible type. Can’t convert an int to a boolean.运行时错误。
不兼容的类型。
无法将一个整型转换为布尔型。
runtime 运行时incompatible 不兼容的convert 转换Which method must be defined by a class implementing the ng.Runnable interface? 在一个实现了ng.Runnable接口的类里,哪个方法必须被定义?method 方法define 定义(动词)definition(名词)implement 实现(动词)implementation(名词)interface 接口Given the following code, what will be the result?假设有如下代码,运行结果会是什么?given 假设有following 如下的Compilation fails because of an error on line 12.编译失败,原因是在第12行出现一个错误。
fail 失败(动词)failure(名词)succeed(反义词:成功,(动词))success(名词)Which two are reserved words in Java?下面哪两个单词是Java中的保留字?reserve 保留,预订(动词)reservation(名词)What is the numerical range of a char?字符型的数值范围是?numerical 数字的,数值的range 范围Which cannot directly cause a thread to stop executing?(下列选项中)哪一个不能直接导致一个线程停止执行?directly 直接地(副词)direct(形容词,动词)cause 导致,造成(动词)原因(名词)thread 线程Which two statements are true regarding the creation of a default constructor?下面哪两句关于默认构造器的创建的说法是正确的?statement 陈述,语句regarding 关于,就…而论creation 创造,创建(名词)create(动词)default 默认的Constructors are used to initialize the instance variables declared in the class.构造器是用来初始化类中声明的实例变量的。
恩士迅java面试英文题Enson Java Interview English Questions1. What is Java?Java is a high-level, object-oriented programming language developed by Sun Microsystems (now owned by Oracle) in 1995. It is known for its platform independence, which means that Java programs can run on any device or operating system that has a Java Virtual Machine (JVM). Java is widely used for creating web applications, mobile applications, desktop software, and enterprise solutions.2. What are the main features of Java?Java has several key features that make it popular among developers:- Object-oriented: Java follows the principles ofobject-oriented programming (OOP), allowing developers to create reusable and modular code.- Platform independence: Java's 'write once, run anywhere' approach allows programs to be run on any device with a JVM, making it highly portable.- Memory management: Java uses automatic garbage collection, freeing developers from managing memory manually. - Multi-threading: Java supports concurrent programmingwith its built-in support for threads, allowing multiple tasks to run simultaneously.- Security: Java provides a secure environment with its built-in security features, such as sandboxing and permission-based access control.3. What is the difference between JDK and JVM?JDK (Java Development Kit) and JVM (Java Virtual Machine) are both essential components of the Java platform, but they serve different purposes.- JDK: JDK is a software development kit that provides tools and libraries necessary for Java development. It includes the Java compiler, debugger, and other utilities required to write, compile, and run Java programs.- JVM: JVM is a runtime environment that executes Java bytecode. It interprets the compiled Java code and converts it into machine code that can be understood by the underlying operating system. JVM also handles memory management and provides various runtime services.4. What is the difference between an abstract class and an interface?- Abstract class: An abstract class is a class that cannot be instantiated and is typically used as a base class for otherclasses. It can contain both abstract and non-abstract methods. Subclasses of an abstract class must implement its abstract methods. An abstract class can also have fields and constructors.- Interface: An interface is a collection of abstract methods and constants. It cannot be instantiated and is used to define a contract for implementing classes. A class can implement multiple interfaces, but it can only extend a single class. Interfaces are used to achieve multiple inheritance in Java.5. What are the different types of exceptions in Java? Java has two types of exceptions: checked exceptions and unchecked exceptions.- Checked exceptions: These are exceptions that are checked at compile-time. The developer must either handle these exceptions using try-catch blocks or declare them in the method signature using the 'throws' keyword. Examples of checked exceptions include IOException and SQLException.- Unchecked exceptions: These are exceptions that are not checked at compile-time. They are subclasses of RuntimeException and Error classes. Unchecked exceptions do not need to be declared or caught explicitly. Examples ofunchecked exceptions include NullPointerException and ArrayIndexOutOfBoundsException.These are just a few sample questions that can be asked during a Java interview. It is important to remember that the depth and complexity of questions may vary depending on the level of the position being applied for. It is advisable to thoroughly prepare and revise various topics related to Java programming to increase the chances of success in a Java interview.。
java英语笔试试题及答案Java英语笔试试题及答案1. What is the difference between a class and an object in Java?A class is a blueprint or template that defines the properties and methods of an object. An object is an instance of a class, created at runtime.2. What is the purpose of the 'public static voidmain(String[] args)' method in Java?The 'public static void main(String[] args)' method is the entry point of a Java application. It is the first methodthat gets executed when the program starts.3. What is the difference between a method and a function in Java?In Java, a method is a block of code that is used to perform a specific task. A function is a term that is often used interchangeably with method, but technically, a function can return a value whereas a method does not necessarily do so.4. What is the 'this' keyword used for in Java?The 'this' keyword in Java is a reference to the current object. It can be used to access instance variables and methods of the current object.5. What is an interface in Java?An interface in Java is a completely abstract class that can contain only abstract methods and constants. It is used to achieve abstraction and to define a contract for classes to implement.6. What is the difference between a checked exception and an unchecked exception in Java?A checked exception is a type of exception that a method must either handle with a try-catch block or declare it with the 'throws' keyword. An unchecked exception is not required to be handled or declared, and includes RuntimeException and its subclasses.7. What is the 'final' keyword used for in Java?The 'final' keyword in Java can be used in three different contexts: to declare a class as final (cannot be subclassed), to declare a method as final (cannot be overridden), or to declare a variable as final (cannot be reassigned).8. What is a constructor in Java?A constructor in Java is a special method that is used to initialize objects. It has the same name as the class and is called when an object is created.9. What is the purpose of the 'super' keyword in Java?The 'super' keyword in Java is used to refer to the parent class's methods and variables. It is often used in constructors to call a superclass's constructor.10. What is the difference b etween '==’ and 'equals()' inJava?The '==' operator is used to compare primitive data types by value and object references by reference, whereas the'equals()' method is used to compare objects by content, and it can be overridden to provide custom comparison logic.Answers:1. A class is a blueprint, an object is an instance of a class.2. It is the entry point of a Java application.3. A method is a block of code in Java, a function is a more general term and can return a value.4. It refers to the current object.5. An interface is an abstract class with only abstract methods and constants.6. Checked exceptions must be handled or declared, unchecked do not.7. It is used to declare classes, methods, or variables as final.8. It initializes objects.9. It refers to the parent class's methods and variables.10. '==' compares by value or reference, 'equals()' compares by content.。
凯捷Java软件工程师笔试题应聘岗位:姓名:一、语言基础(每题4分,共16分)1.说说Collection和Collections的区别?2.说说final,finally,finalize的区别?3.说说java中的wait()和notify()方法使用时应注意些什么?4.说说throw和throws的区别?二、数据库基础(每题5分,共15分)5.说说内连接、左连接、右连接的区别?6.说说SQL中JOIN和FULL JOIN 的区别?IN和EXISTS的区别?7.在RDBMS中通过哪些约束可以保证数据库的实体完整性及参照完整性?三、Web基础(每题5分,共25分)8.用Javascript动态创建一个div元素,将id设置为“mydiv”,字体颜色为绿色,字号14,粗体,内容为”Javascript DIV”。
最后将该元素追加到body 中来显示(注:所有这些要求都使用javascript来完成,也可以使用jQuery 来完成)。
9.Ajax编程中所使用的Javascript对象是什么?怎么去创建它?如何取服务器响应给客户端的XML对象信息10.说说Servlet的生命周期以及所涉及的方法?11.说说Servlet API中forward与redirect的区别?12.说说你所了解的JSP有哪些隐式对象?各有什么作用?它们所对应的Servlet API接口类型是什么?四、综合题(13-18每题5分,18-19每题7分,共44分)13.如果你试图编译并运行下面的代码将会发生什么?public class Test{public static void main(String ss[]){float f=3.4;int anar[]=new int[5];System.out.println(anar[0]);}}14.写一个简单的单态类(Singleton pattern class)。
15.说说设计模式中抽象工厂和工厂方法区别16.什么是MVC?谈谈你对MVC的认识。
1.Which of the following lines will compile without warning or error.答案(5)1) float f=1.3;2) char c="a";3) byte b=257;4) boolean b=null;5) int i=10;2. What will happen if you try to compile and run the following codepublic class MyClass {public static void main(String arguments[]) {amethod(arguments);}public void amethod(String[] arguments) {System.out.println(arguments);System.out.println(arguments[1]);}}答案(1)1) error Can't make static reference to void amethod.2) error method main not correct3) error array must include parameter4) amethod must be declared with String3. Which of the following will compile without error答案(23)1) import java.awt.*;package Mypackage;class Myclass {}2) package MyPackage;import java.awt.*;class MyClass{}3) /*This is a comment */package MyPackage;import java.awt.*;class MyClass{}4. What will be printed out if this code is run with the following command line? java myprog good morningpublic class myprog{public static void main(String argv[]){System.out.println(argv[2]);}}答案(4)1) myprog2) good3) morning4) Exception raised:"ng.ArrayIndexOutOfBoundsException: 2"5. What will happen when you compile and run the following code? public class MyClass{static int i;public static void main(String argv[]){System.out.println(i);}}答案(4)1) Error Variable i may not have been initialized2) null3) 14) 06. What will happen if you try to compile and run the following code? public class Q {public static void main(String argv[]){int anar[]=new int[]{1,2,3};System.out.println(anar[1]);}}答案(3)1) 12) Error anar is referenced before it is initialized3) 24) Error: size of array must be defined7. What will happen if you try to compile and run the following code? public class Q {public static void main(String argv[]){int anar[]=new int[5];System.out.println(anar[0]);}}答案(3)1) Error: anar is referenced before it is initialized2) null3) 04) 58. What will be the result of attempting to compile and run the following code?答案(3)abstract class MineBase {abstract void amethod();static int i;}public class Mine extends MineBase {public static void main(String argv[]){int[] ar=new int[5];for(i=0;i < ar.length;i++)System.out.println(ar[i]);}}1) a sequence of 5 0's will be printed2) Error: ar is used before it is initialized3) Error Mine must be declared abstract4) IndexOutOfBoundes Error9. What will be printed out if you attempt to compile and run the following code ? int i=1;switch (i) {case 0:System.out.println("zero");break;case 1:System.out.println("one");case 2:System.out.println("two");default:System.out.println("default");}答案(3)1) one2) one, default3) one, two, default4) default10. Which of the following lines of code will compile without error答案(23)1) int i=0;if(i) {System.out.println("Hello");}2) boolean b=true;boolean b2=true;if(b==b2) {System.out.println("So true");}3) int i=1;int j=2;if(i==1|| j==2)System.out.println("OK");4) int i=1;int j=2;if(i==1 &| j==2)System.out.println("OK");11. What will be output if you try to compile and run the following code, but there is no file called Hello.txt in the current directory?.import java.io.*;public class Mine{public static void main(String argv[]){Mine m=new Mine();System.out.println(m.amethod());}public int amethod(){try{FileInputStream dis=new FileInputStream("Hello.txt");}catch (FileNotFoundException fne){System.out.println("No such file found");return -1;}catch(IOException ioe){}finally{System.out.println("Doing finally");}return 0;}}答案(3)1) No such file found2 No such file found ,-13) No such file found, Doing finally, -14) 012.Which of the following statements are true?答案(1)1) Methods cannot be overriden to be more private2) static methods cannot be overloaded3) private methods cannot be overloaded4) An overloaded method cannot throw exceptions not checked in the base class13.What will happen if you attempt to compile and run the following code?答案(3)class Base {}class Sub extends Base {}class Sub2 extends Base {}public class CEx{public static void main(String argv[]){Base b=new Base();Sub s=(Sub) b;}}1) Compile and run without error2) Compile time Exception3) Runtime Exception14.Which of the following statements are true?答案(123)1) System.out.println( -1 >>> 2);will output a result larger than 102) System.out.println( -1 >>> 2); will output a positive number3) System.out.println( 2 >> 1); will output the number 14) System.out.println( 1 <<< 2); will output the number 415.What will happen when you attempt to compile and run the following code? public class Tux extends Thread{static String sName = "vandeleur";public static void main(String argv[]){Tux t = new Tux();t.piggy(sName);System.out.println(sName);}public void piggy(String sName){sName = sName + " wiggy";start();}public void run(){for(int i=0;i < 4; i++){sName = sName + " " + i;}}}答案(4)1) Compile time error2) Compilation and output of "vandeleur wiggy"3) Compilation and output of "vandeleur wiggy 0 1 2 3"4) Compilation and output of either "vandeleur", "vandeleur 0", "vandeleur 0 1" "vandaleur 0 1 2" or "vandaleur 0 1 2 3"16.What will be displayed when you attempt to compile and run the following code//Code startimport java.awt.*;public class Butt extends Frame{public static void main(String argv[]){Butt MyBut=new Butt();}Butt(){Button HelloBut=new Button("Hello");Button ByeBut=new Button("Bye");add(HelloBut);add(ByeBut);setSize(300,300);setVisible(true);}}//Code end答案(3)1) Two buttons side by side occupying all of the frame, Hello on the left and Bye on the right2) One button occupying the entire frame saying Hello3) One button occupying the entire frame saying Bye4) Two buttons at the top of the frame one saying Hello the other saying Bye17.What will be output by the following code?public class MyFor{public static void main(String argv[]){int i;int j;outer:for (i=1;i <3;i++)inner:for(j=1; j<3; j++) {if (j==2)continue outer;System.out.println("Value for i=" + i + " Value for j=" +j); }}}答案(12)1) Value for i=1 Value for j=12) Value for i=2 Value for j=13) Value for i=2 Value for j=24) Value for i=3 Value for j=118.Which statement is true of the following code?public class Agg{public static void main(String argv[]){Agg a = new Agg();a.go();}public void go(){DSRoss ds1 = new DSRoss("one");ds1.start();}}class DSRoss extends Thread{private String sTname="";DSRoss(String s){sTname = s;}public void run(){notwait();System.out.println("finished");}public void notwait(){while(true){try{System.out.println("waiting");}catch(InterruptedException ie){}System.out.println(sTname);notifyAll();}}}答案(4)1) It will cause a compile time error2) Compilation and output of "waiting"3) Compilation and output of "waiting" followed by "finished"4) Runtime error, an exception will be thrown19.Which of the following methods can be legally inserted in place of the comment //Method Here ?class Base{public void amethod(int i) { }}public class Scope extends Base{public static void main(String argv[]){}//Method Here}答案(23)1) void amethod(int i) throws Exception {}2) void amethod(long i)throws Exception {}3) void amethod(long i){}4) public void amethod(int i) throws Exception {}20.You have created a simple Frame and overridden the paint method as followspublic void paint(Graphics g){g.drawString("Dolly",50,10);}What will be the result when you attempt to compile and run the program?答案(3)1) The string "Dolly" will be displayed at the centre of the frame2) An error at compilation complaining at the signature of the paint method3) The lower part of the word Dolly will be seen at the top of the frame, with the top hidden.4) The string "Dolly" will be shown at the bottom of the frame.21.What will be the result when you attempt to compile this program?public class Rand{public static void main(String argv[]){iRand = Math.random();System.out.println(iRand);}}答案(1)1) Compile time error referring to a cast problem2) A random number between 1 and 103) A random number between 0 and 14) A compile time error about random being an unrecognised method22.Given the following codeimport java.io.*;public class Th{public static void main(String argv[]){Th t = new Th();t.amethod();}public void amethod(){try{ioCall();}catch(IOException ioe){}}}What code would be most likely for the body of the ioCall method答案(1)1) public void ioCall ()throws IOException{DataInputStream din = new DataInputStream(System.in);din.readChar();}2) public void ioCall ()throw IOException{DataInputStream din = new DataInputStream(System.in);din.readChar();}3) public void ioCall (){DataInputStream din = new DataInputStream(System.in);din.readChar();}4) public void ioCall throws IOException(){DataInputStream din = new DataInputStream(System.in);din.readChar();}23.What will happen when you compile and run the following code?public class Scope{private int i;public static void main(String argv[]){Scope s = new Scope();s.amethod();}//End of mainpublic static void amethod(){System.out.println(i);}//end of amethod}//End of class答案(3)1) A value of 0 will be printed out2) Nothing will be printed out3) A compile time error4) A compile time error complaining of the scope of the variable i24.You want to lay out a set of buttons horizontally but with more space between the first button and the rest. You are going to use the GridBagLayout manager to control the way the buttons are set out. How will you modify the way the GridBagLayout acts in order to change the spacing around the first button?答案(2)1) Create an instance of the GridBagConstraints class, call the weightx() method and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.2) Create an instance of the GridBagConstraints class, set the weightx field and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.3) Create an instance of the GridBagLayout class, set the weightx field and then call the setConstraints method of the GridBagLayoutClass with the component as a parameter.4) Create an instance of the GridBagLayout class, call the setWeightx() method and then pass the GridBagConstraints instance with the component to the setConstraints method of the GridBagLayout class.25.Which of the following can you perform using the File class?答案(23)1) Change the current directory2) Return the name of the parent directory3) Delete a file4) Find if a file contains text or binary information26.Which statement is true of the following code?public class Rpcraven{public static void main(String argv[]){Pmcraven pm1 = new Pmcraven("One");pm1.run();Pmcraven pm2 = new Pmcraven("Two");pm2.run();}}class Pmcraven extends Thread{private String sTname="";Pmcraven(String s){sTname = s;}public void run(){for(int i =0; i < 2 ; i++){try{sleep(1000);}catch(InterruptedException e){}yield();System.out.println(sTname);}}}答案(2)1) Compile time error, class Rpcraven does not import ng.Thread2) Output of One One Two Two3) Output of One Two One Two4) Compilation but no output at runtime27.You are concerned that your program may attempt to use more memory than is available. To avoid this situation you want to ensure that the Java Virtual Machine will run its garbage collection just before you start a complex routine. What can you do to be certain that garbage collection will run when you want .答案(1)1) You cannot be certain when garbage collection will run2) Use the Runtime.gc() method to force garbage collection3) Ensure that all the variables you require to be garbage collected are set to null4) Use the System.gc() method to force garbage collection28、Which statements about the garbage collection are true?答案(2)1. The program developer must create a thread to be responsible for free the memory.2. The garbage collection will check for and free memory no longer needed.3. The garbage collection allow the program developer to explicity and immediately free the memory.4. The garbage collection can free the memory used java object at expect time.29.You have these files in the same directory. What will happen when you attempt to compile and run Class1.java if you have not already compiled Base.java//Base.javapackage Base;class Base{protected void amethod(){System.out.println("amethod");}//End of amethod}//End of class basepackage Class1;//Class1.javapublic class Class1 extends Base{public static void main(String argv[]){Base b = new Base();b.amethod();}//End of main}//End of Class1答案(4)1) Compile Error: Methods in Base not found2) Compile Error: Unable to access protected method in base class3) Compilation followed by the output "amethod"4)Compile error: Superclass Class1.Base of class Class1.Class1 not found30.What will happen when you attempt to compile and run the following codeclass Base{private void amethod(int iBase){System.out.println("Base.amethod");}}class Over extends Base{public static void main(String argv[]){Over o = new Over();int iBase=0;o.amethod(iBase);}public void amethod(int iOver){System.out.println("Over.amethod");}}答案(4)1) Compile time error complaining that Base.amethod is private2) Runtime error complaining that Base.amethod is private3) Output of "Base.amethod"4) Output of "Over.amethod"一个袋子中有100个黑球,100个白球,每次从中取出两个球,然后放回一个球,如果取出两个球颜色相同,则放入一个黑球,如果取出一百一黑,则放入一个白球,请问到最后袋中剩下的球的颜色:1)黑球2)白球3)不一定。