Java中的main函數

1. package com.han;  
2.   
3. public class HanTest {  
4.     public static void main(String[] args){  
5.         if(args==null){  
6.             throw new NullPointerException("The input is \"null\"");  
7.         }else if((args.length!=1&&args.length!=2)){  
8.             Throwable cause=new Throwable("You have to input 1 or 2 String arguments");  
9.             throw new IllegalArgumentException("Wrong numbers of args",cause);  
10.             //throw new IllegalArgumentException("Wrong numbers of args");   
11.         }else if(args.length==1){  
12.             System.out.println(args[0]);  
13.         }else if(args.length==2){  
14.             System.out.println(args[0]);  
15.             System.out.println(args[1]);  
16.         }  
17.     }  
18. }  

 [java]

1. package com.han;  
2. public class HanTest2 {  
3.     public static void main(String[] args){  
4.         String[] input={"han"};  
5.         //HanTest.main(null);   
6.         HanTest.main(input);  
7.     }  
8. }