北京东华合创数码科技股份有限公司
笔试试卷（Java 语言部分）
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1. which won’t cause a compiler warning or error？(多选)
a) float f = 1.3;
b) char c = ‘a’;
c) byte b = 257;
d) boolean b = null;
e) int i = 10;
2. 请选择下面这段代码的输出结果?
int i = 0;
switch (i) {
case 0:
System.out.println("zero");
case 1:
System.out.println("one");
case 2:
System.out.println("two");
break;
case 3:
System.out.println("three");
}
1) zero
2) zero,one
3) zero,one,two
4) zero,one,two,three
3. public class Test{
private static int j=0;
public static boolean methodB(int k){
j+=k;
return true;
}
public static void methodA(int i){
boolean b;
b=i>10&methodB(1);
b=i>10&&methodB(2);
}
public static void main(String args){
methodA(0);
17)
}
}
what is the value of j at line 17?
1）0
2）1
3）2
4）3
4. If we execute the code below with “java Test Red Green Blue”, what is the result? public class Test{
public static void main(String[] args){
String foo=args[1];
String bar=args[2];
String baz=args[3];
}
}
what is the value of baz?
A. baz has value of ""
B. baz has value of null
C. baz has value of "Red"
D. baz has value of "Blue"
E. baz has value of "Green"
F. the code does not compile
G. the program throw an exception
5. 请选择下面这段代码的输出结果?
1)public class Test{
2)public static void main(String[] args){
3) class Foo{
4) public int i=3;
5) }
6)Object o=(Object)new Foo();
7) Foo foo=(Foo)o;
8)System.out.println(foo.i);
9) }
10) }
https://www.doczj.com/doc/8f4140857.html,pile error at line 6
https://www.doczj.com/doc/8f4140857.html,pile error at line 7
https://www.doczj.com/doc/8f4140857.html,pile error at line 8
D.print out 3
6.
int index=1;
String[] test=new String[3];
String foo=test[index];
what is the result of foo?
A. ""
B.null
C.throw a Exception
D.not compile
7. 下面的五个选择中哪两个描述是正确的？（多选）
A. static inner class requires a static initializer
B. A static inner class requires an instance of the enclosing class
C. A static inner class has no reference to an instance of the enclosing class
D. A static inner class has accesss to the non-static member of the other class
E. static members of a static inner class can be referenced using the class
name of the static inner class
8. 请选择下面这段代码的输出结果?
class A{
public int getNumber(int a){
return a+1;
}
}
class B extends A{
public int getNumber(int a, char c){
return a+2;
}
public static void main(String[] args){
B b=new B();
System.out.println(b.getNumber(0));
}
}
A. compilation succeeds and 1 is printed
B. compilation succeeds and 2 is printed
C. An error at line 8 cause compilation to fail
D. An error at line 14 cause compilation to fail
9. class ExceptionTest{
public static void main(String args[]){
try{
methodA();
}
catch(IOException e){
System.out.println("caught IOException");
}
catch(Exception e){
System.out.println("caught Exception");
}
}
}
If methodA() throws a IOException, what is the result? If we change the sequence of catch,what’s the result？
10. 请写出下面这段代码的输出结果?
public class Test{
public static void main(String[] args){
StringBuffer a=new StringBuffer("A");
StringBuffer b=new StringBuffer("B");
operate(a,b);
System.out.pintln(a+","+b);
}
public static void operate(StringBuffer x, StringBuffer y){ x.append(y);
y=x;
}
}
11. 请写出下面这段代码的输出结果?
class Shape{
Shape(int i){
System.out.println("This is Shape" + i);
}
}
public class Circle extends Shape{
static Shape s1 = new Shape(1);
Shape s2 = new Shape(3);
Circle(int i){
super(i);
System.out.println("This is Circle" + i);
}
public static void main(String args[]){
Circle c1 = new Circle(2);
}
}
12.数组有没有length()这个方法? String有没有length()这个方法?