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. }