Question

我试图通过传递主机名来获取主机地址。但是在运行我的代码时，我得到了例外：

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
    at socketprogram_client.SocketProgram_Client.main(SocketProgram_Client.java:16)
Java Result: 1

有人可以告诉我为什么会收到此错误吗？

这是我的代码：

package socketprogram_client;

import java.io.*;
import java.net.*;

public class SocketProgram_Client 
{
    public static void main ( String args[] ) throws IOException 
    {
        String host_name = args[0];

        try
        {
            InetAddress my_ipaddr = InetAddress.getByName(host_name);
            System.out.println("Resolved to IP address: " + my_ipaddr.getHostAddress());
        }
        catch ( UnknownHostException e )
        {
            System.out.println("Could not find IP address for: " + host_name);
        }
    }
}

Answer 1

看来你没有传递任何论据。你应该做一些检查：

public static void main ( String args[] ) throws IOException 
{
    if(args == null || args.length == 0){
        System.out.println("You didn't pass in any arguments!");
    }
    else{
        //rest of code
    }
}

运行程序时，必须在命令行中有一个参数：

java SocketProgram_Client the_argument

the_argument是您传入的参数（args[0]）。

Answer 2

您可能没有将参数传递给args，因此args[0]可能为空。

package socketprogram_client;

import java.io.*;
import java.net.*;

public class SocketProgram_Client 
{
    public static void main ( String args[] ) throws IOException 
    {
        if(args.length == 0){
            System.out.println("You didn't say a host name");
            System.exit(1);
        }

        String host_name = args[0];

        try
        {
            InetAddress my_ipaddr = InetAddress.getByName(host_name);
            System.out.println("Resolved to IP address: " + my_ipaddr.getHostAddress());
        }
        catch ( UnknownHostException e )
        {
            System.out.println("Could not find IP address for: " + host_name);
        }
    }
}

线程“main”中的异常java.lang.ArrayIndexOutOfBoundsException：0

2 个答案: