Java会出现＂unreachable code＂错误的几个例子

 public class exam {
     static int num=5;
     static int m1(){
         try{
             num=6;
             throw new NullPointerException();
             System.out.println("111");　　　　//编译不通过
         }catch(ArrayIndexOutOfBoundsException e){
             num=10;
             System.out.println("222");
         }catch(Exception e){
             num+=1;
             System.out.println("333");
             return num;
         }finally{
             num=10;
             System.out.println("444");
             throw new NullPointerException();
         }
     }

     public static void main(String[] args) {
         try{
             m1();
             num=20;
         }catch(Exception e){
             num+=1;
             System.out.println("555");
         }
         System.out.println(exam.num);

     }
 }

输出结果：

Exception in thread "main" java.lang.Error: Unresolved compilation problem:
Unreachable code

at exam.m1(exam.java:8)
at exam.main(exam.java:25)

1. throw关键字

Java代码:  

1. public void XXX() throws Throwable{
2. throw new Throwable();
3. System.out.println("test");
4. }

2. return关键字

Java代码 : 

1. public void XXX() {
2. return;
3. System.out.println("test");
4. }

3. continue关键字

Java代码:  

1. public void XXX() {
2. for(int i=0; i<10; i++) {
3. continue;
4. System.out.println("test");
5. }
6. }

4. break关键字

Java代码:  

1. public void XXX() {
2. for(int i=0; i<10; i++) {
3. if(i==5) {
4. break;
5. System.out.println("test");
6. }
7. }
8. }

5. while(true):

Java代码:  

1. public static void XXX() {
2. while(true);
3. System.out.println("when?");
4. }