待解：使用命令行实参的方法

 1 package com.java7;
 2 // A simple automated telephone directory.
 3 class Phone {
 4     public static void main(String[] args) {
 5         String numbers[][] = {
 6                 { "Tom", "555-3322" },
 7                 { "Mary", "555-8976" },
 8                 { "Jon", "555-1037" },
 9                 { " Rachel", "555-1400"}
10         };
11         
12         int i;
13         
14         if(args.length != 1) // 要使用程序，必须提供一个命令行实参
15             System.out.println("Usage: java Phone <name>");
16         else {
17             for(i = 0; i < numbers.length; i++){
18                 if(numbers[i][0].equals(args[0])) {
19                     System.out.println(numbers[i][0] + ": " + numbers[i][1]);
20                     break;
21                 }
22             }
23             if(i == numbers.length)
24                 System.out.println("Name not found.");
25         }
26     }
27 }