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我正在尝试将多个数据包从 android 服务器发送到客户端，但问题是代码仅在 2 次迭代后停止，然后它以未捕获的异常退出，所以我做错了什么。你能帮我吗？

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainTalker extends Activity 
{
private static DatagramSocket socket;
private static DatagramPacket packet;
private static Thread send;
private Button cl1;
private static EditText ed1;
private static String msg = "Message";
private static byte[] data = new byte[15];
//private static byte[] pktcount = new byte[10];
private static String TAG = "Sender UDP";
static int count=0;
static String[] output = new String[100] ;

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_talker);

    ed1 = (EditText) findViewById(R.id.msg);
    cl1 = (Button) findViewById(R.id.send);

    try {
        socket = new DatagramSocket(11001);
        Toast toast = Toast.makeText(getApplicationContext(),"Port Opened",Toast.LENGTH_SHORT);
        toast.show();
        System.out.println("Port Opened ");
        socket.setBroadcast(true);
    } catch (Exception e) {
        System.out.println("Exception: Port not opened");
        e.printStackTrace();
        Log.e(TAG, e.getMessage());
    }

    cl1.setOnClickListener(new View.OnClickListener() 
    {
        public void onClick(View v) 
        {
            System.out.println("Button Clicked ");

            send = new sendthr();
            send.start();
        }
    });
}

private static class sendthr extends Thread {
    public void run()
    {
            System.out.println("Thread Started");

            String messg = ed1.getText().toString();
            System.out.println(messg);
            for (int i=0; i<=messg.length(); i+=10)
            {
                if(messg.length()>i+10)
                    output[i] = messg.substring(i,i+10);
                else
                    output[i]=messg.substring(i);
                count++;
                output[i+1] =count + ": " + output[i];
                System.out.println(output[i+1]);
            }
            output[0] = Integer.toString(count);
            System.out.println(count);
            if (messg == null)
                messg = msg;
            int i =0;
            while(i !=count)
            {
            data = output[i].getBytes();
            try
            { //Create packet with target host and target port
                packet = new DatagramPacket(data,data.length,InetAddress.getByName("192.168.8.17"), 11001);
                System.out.println("Packet Created");

            } catch (UnknownHostException e) {
                System.out.println("Exception: Packet Created");

                e.printStackTrace();
                Log.e(TAG, e.getMessage());
            }

            try
            {
                System.out.println("Sending the packet  "+ msg);
                socket.send(packet);
                System.out.println("Packet sent");
            } catch (IOException e) {
                System.out.println("Exception: Packet Send");
                e.printStackTrace();
                Log.e(TAG, e.getMessage());
            }
            i++;
        }     
}

} }

*这是我遇到的错误消息：

11-22 15:58:59.381: W/dalvikvm(1223): threadid=11: thread exiting with uncaught exception (group=0x40a13300)
11-22 15:59:00.251: E/AndroidRuntime(1223): FATAL EXCEPTION: Thread-114
11-22 15:59:00.251: E/AndroidRuntime(1223): java.lang.NullPointerException
11-22 15:59:00.251: E/AndroidRuntime(1223):     at com.example.a_talker.MainTalker$sendthr.run(MainTalker.java:89)
11-22 15:59:00.701: W/IInputConnectionWrapper(1223): showStatusIcon on inactive InputConnection*
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1 回答 1

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你在第 89 行得到了 NPE。根据我的计算，它是：

packet = new DatagramPacket(data,data.length,InetAddress.getByName("192.168.8.17"), 11001);

如果是这样，那么很可能data是null。（如果第 89 行在别处，请指出是哪一行）。

也不叫

System.out.println(count);

在安卓上。做

Log.i( TAG, "count: " + count );

你在多个地方得到了这个（第 54、80、93、101、103、105 行......），所以把它们都修好

于 2012-11-22T22:09:17.360 回答