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史上最全的面试题-“java无敌面试题”

[“ '”? ]

JAVASE

1..java

public

2. float float f=

3.4? float f=1.3;?short s1 = 1; s1 = s1 + 1;?

,float f=(float)3.4 float f=(float)1.3short s1 = 1; s1 = s1 + 1;s1+1int short s1 = 1; s1 += 1;

3.Java goto?

goto java java

4.Java main()

Java main()Java main()

main public static void

5.&&&(&,|,^)(&&,||)

&&&and a., , b.

6.Math.round(11.5) ? Math.round(-11.5)?

Math.round(11.5)==12 Math.round(-11.5)==-11 round 1/2 floor

switch expr1expr1 switch case int short char byte long,string swtich

Java

9.Overload Override Overloaded ?

Overriding Overloading Java Overriding

Overloading

(Overriding)

(Overloading)Overloaded

10.Constructor override?

Constructor Overriding Overloading

11.?

12.Abstract class interface ?

abstract class

abstract

Abstract

interface

static final

instanceof

13.? (implements)? (concrete class)?

(implements)

14.

,public,static,final

15.abstract method static,final,native synchronized?

16.static static

,method()

17.Override this?

18.

19.String ?true

A beijing==beijing

B beijing.equalsIgnoreCase new String beijing

A B

20.String, StringBuffer StringBuilder

String StringBuffer

StringBuffer String StringBuffer toString()StringBuilder JDK 5 StringBuffer StringBuilder

21.String s=new String(xyz);String Object? String s1 = xyz

"xyx","xyx"s

22.==equals()

equals

23.(x.equals(y) == true)hash code

hash code

24.int Integer

Java int java Integer java int Java

: boolean,char,byte,short,int,long,float,double

Boolean Character Byte Short Integer Long Float Double

null

25.new Object[5]5

26.List,Set,Map Collection

List,Set Map

27.

List Map List ArrayList Vector

List Map Map

28.ArrayList,Vector, LinkedList

ArrayList Vector

Vector synchronized ArrayList LinkedList

29.Collection Collections

Collection java.util Set List Collections java.util

30.HashMap Hashtable ?

Map

1)HashMap null null ,Hashtable

2)HashMap Hashtable contains containsvalue containsKey,contains

3)Hashtable Dictionary HashMap Java1.2 Map

4)Hashtable Synchronize HashMap Hashtable

HashMap Hashtable HashMap hash/rehash

31.Arraylist Vector

ArrayList Vector

1Vector ArrayList

2,Vector ArrayList

32.List Map Set

List Set ,Map key-value value

33.

34.Set ? ==equals()? ?

Set equals ()equals()== ,

35.Java

JAVA JAVA JAVA 2 JAVA

,IndexOutOfBoundsException;null NullPointerException JAVA throw

https://www.doczj.com/doc/2d9495890.html,ng.Thowable

36.error exception ?

error

exception

37.try {}return try finally {}code return

return

38.JAVA throws,throw,try,catch,finally try

Java Java

Throwable

Java 5 try catch throw throws finally try throws catch

finally

try

catch try

throw

throws

Finally

try try try

try try

try

39.

java

40.runtime exception

ArrayStoreException, BufferOverflowException,ClassCastException, CMMException, DOMException, EmptyStackException, IllegalArgumentException,IndexOutOfBoundsException,NullPointerException,SecurityException

41.final, finally, finalize ?

final final

abstract final final final

final

finally finally catch

finally finalize Java finalize()

Object

finalize() finalize()

42.Static Nested Class Inner Class

Static Nested Class static

43.

44.Anonymous Inner Class () extends()implements()interface()?

swing

45.java java

Serializable implements Serializable

(FileOutputStream)ObjectOutputStream()ObjectOutputStream

writeObject(Object obj)obj ()

46.java JDK

InputStream OutputStream Reader Writer java.io

47.sleep() wait() ?

sleep Thread

sleep wait Object wait

notify notifyAll

48.synchronized ?

49.

wait():lock sleep():

InterruptedException notify():

JVM notityAll():

50.,?,?

Thread Runnable ,synchronized,wait notify 51.

52.run()start()?

start()JVM

run()

53.

Java

54.synchronized java.util.concurrent.locks.Lock

Lock synchronized Lock synchronized

synchronized Lock finally

55.java ?stop()suspend()

Thread Runnable synchronized stop()

suspend()suspend()

suspend()Thread

wait()notify()

56.JVM class ?

JVM ClassLoader ,Java ClassLoader Java

57.java

58.GC ? GC?

GC Gabage Collection,

Java GC Java

Java

System.gc() Runtime.getRuntime().gc()

59. 2

Java c++Java

Java

60.

GC GC GC

(heap)""""GC "" GC System.gc()GC Java GC

61. JAVA

Java break

ok:

for(int i=0;i<10;i++) {

for(int j=0;j<10;j++) {

System.out.println(“i=” + i + “,j=” + j);

if(j == 5) break ok;

}

int arr[][] = {{1,2,3},{4,5,6,7},{9}};

boolean found = false;

for(int i=0;i

for(int j=0;j

System.out.println(“i=” + i + “,j=” + j);

if(arr[i][j] == 5) {

found = true;

break;

}

62. ?

1. String [] result = orgStr.split(,);

2. StingTokenizer ,

StringTokenizer tokener = StringTokenizer(orgStr,,);

String [] result = new String[tokener .countTokens()];

Int i=0;

while(tokener.hasNext(){

result[i++]=toker.nextToken();

}

63. List Map ?

List Map

64.?

IO OutputStream InputStream

JSP-SERVLET

1.JSP?

request GET/POST

response

pageContext

session

application Servlet

out

config servlet

page JSP

exception

2.JSP?

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@include file="filename"%>

<%@taglib uri="https://www.doczj.com/doc/2d9495890.html,/jsp/jstl/core" prefix="c" %>

3.JSP,?

jsp include

jsp useBean JavaBean

jsp setProperty JavaBean

jsp getProperty JavaBean

jsp foward

jsp plugin Java OBJECT EMBED

4.JSP include include?

include jsp include

include include

5.?

1.forward

2.response response.sendRedirect("");

1.forward a. b.(

) c.request d.

2.response a., b. c.request

d.respons

e.sendRedirect("URL?")

6.?

1.page java servlet include

include servlet servlet jsp

2.request web web

3.session web web

4.application web web

7.JSP servlet browser cache?

jsp

response.setHeader("Cache-Control","no-store");

response.setHeader("Pragma","no-cache");

response.setDateHeader("Expires",0);

8.JSP cookie?

Cookie mycookie=new Cookie("aName","aValue");

Cookie killMyCookie=new Cookie("mycookie",null);

killMyCookie.setMaxAge(0);----setMaxAge()cookie

killMyCookie.setPath("/");

response.addCookie(killMyCookie);

9.servlet3.0?

1. Servlet

2.4Java 5Java 5servlet class web.xml servlet

3.0servlet web.xml

2. Servlet

3.0 Servlet 3.0Ajax Servlet

10.servlet?

<%@ page isThreadSafe="false" %>

11.Servlet Servlet CGI?

Servlet init service service

doXXX doGet doPost destroy

cgi servlet service

CGI servlet

12.JSP Servlet?

Jsp Servlet Servlet JSP“servlet”Servlet JSP Servlet java HTML jsp java html .jsp JSP servlet

13.WEB,HTTP

1.HTTP HTTP

3.HTTP()

5.servlet HTTP servlet

7.()

8.HTTP

9.Web

10.

MySQL

1.mysql

MySQL mysql mysql_install_db user db table_priv columns_priv host

user

table_priv

columns_priv

host db GRANT REVOKE

2.MYSQL

MYSQL autocommit mysql

MYSQL InnoDB Tables BDB tables MYSQL,SET AUTOCOMMIT=0MYSQL autocommit

autocommit COMMIT ROLLBACK