Help! App Waits until Force Close on Second Run

I am very new to android, and I have thrown together a simple app to test out multi-casting packets in an AsyncTask.

The first time I run the app everything goes as I expect, but if I close it and attempt to run it a second time the app just hangs until the force close dialog launches.

After this I can once again run the program normally one time, and so on. I assume that there is something that I am not closing properly.

I have checked logCat, but the only messages I get are:

WARN/ActivityManager(1193): Activity idle timeout for HistoryRecord{45b352c0 android.projects.bserver/.BroadcastServer}
WARN/ActivityManager(1193): Activity pause timeout for HistoryRecord{45b352c0 android.projects.bserver/.BroadcastServer}

If anyone can tell me what I'm doing wrong that's causing the freeze on the second run, I would be grateful.

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import android.app.Activity;
import android.content.Context;
import android.net.DhcpInfo;
import android.net.wifi.WifiManager;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

public class BroadcastServer extends Activity {
public static final int PORT = 1200;
TextView textStatus;
String data = "this is a test";
public static boolean running = true;


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

    textStatus = (TextView)findViewById(R.id.writeBlock);

    textStatus.append("\nStarting");

    MyAsync ma = new MyAsync();
    ma.execute(data);
    textStatus.append("\nTaskRunning");
    /////////////////////////////////////////////
    try
    {
        InetAddress address = getBroadcastAddress();/////////
        InetAddress multiGroup = InetAddress.getByName("224.0.5.255");

        ///////////////////////////////time to receive

        MulticastSocket socket2 = new MulticastSocket(PORT);//////
        socket2.joinGroup(multiGroup);

        byte[] buf = new byte[1024]; 
        DatagramPacket packet2 = new DatagramPacket(buf, buf.length); 

        textStatus.append("\nWaiting to Receive");

        socket2.receive(packet2);

        textStatus.append("\nReceived");

        String received = new String(packet2.getData());

        textStatus.append("\n" + received);
        running = false;

        textStatus.append("\nFinished");

    }
    catch(IOException e)
    {
        textStatus.append("\nTaskFailed Outer: " + e.getMessage());
    }
    textStatus.append("\nProgramDone");
}

///////////////////////////////////////////////////

InetAddress getBroadcastAddress() throws IOException { 
    //Original Line: WifiManager wifi = mContext.getSystemService(Context.WIFI_SERVICE);
    WifiManager wifi = (WifiManager)this.getSystemService(Context.WIFI_SERVICE);

    DhcpInfo dhcp = wifi.getDhcpInfo();
    // handle null somehow      
    int broadcast = (dhcp.ipAddress & dhcp.netmask) | ~dhcp.netmask;     
    byte[] quads = new byte[4];     
    for (int k = 0; k < 4; k++)       
        quads[k] = (byte) ((broadcast >> k * 8) & 0xFF);     
    return InetAddress.getByAddress(quads); 
}

class MyAsync extends AsyncTask<String, Integer, String>
{
    @Override
    protected void onPreExecute()
    {
        textStatus.append("\nAsyncStarted");
    }

    @Override
    protected String doInBackground(String... params) {
        ///////////////////////////////time to send
      开发者_如何学Go  String data = params[0];

        try
        {
        InetAddress address = getBroadcastAddress();///////////////
        InetAddress multiGroup = InetAddress.getByName("224.0.5.255");

        MulticastSocket socket = new MulticastSocket(PORT);
        socket.setBroadcast(true); 
        socket.joinGroup(multiGroup);//////////
        DatagramPacket packet = new DatagramPacket(data.getBytes(), 
                data.length(), address, PORT); 

        //int count = 0;
        while(BroadcastServer.running)
        {
            socket.send(packet);  
            //publishProgress(count);
            //count++;
        }
        }
        catch(IOException e)
        {
            textStatus.append("\nTaskFailed Inner: " + e.getMessage());
        }

        return "AsyncDone";
    }

    @Override
    protected void onProgressUpdate(Integer... count)
    {
        textStatus.append("\n" + count.toString());
    }

    @Override
    protected void onPostExecute(String results)
    {
        textStatus.append("\n"+results);
    }
}
}

Firstly, you said it force closes, but I suspect what you are seeing is not a Force Close, but an Application Not Responding (ANR) which is quite different. An ANR isn't a crash, it means your app is tied up doing something time-consuming on the UI thread.

You're making a network call on the UI thread. You've moved some to an AsyncTask, but you need to get everything network-related off the UI thread. If you comment out the network code, your app will be responsive again.

As a general tip, you may also wish to learn about IntentService, which is another approach to passing off actions to be performed in the background.