Question

I want to display a progressdialog when a client sends request to the server..the request should be done in background…but i am getting a force close when i use the AsyncTask..Please help ..Thank you

package com.example.client;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;

import android.os.AsyncTask;
import android.os.Bundle;
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends Activity {

    public static ProgressDialog Dialog;
    String s1;

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

        findViewById(R.id.button1).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // sendreq();
                new SendUserTask().execute();
            }
        });
    }

    public String sendreq() {
        try {
            // TODO Auto-generated method stub
            SocketAddress sockaddr = new InetSocketAddress("192.168.7.116",
                    9011);
            Socket serversocket = new Socket();
            serversocket.connect(sockaddr, 10000);
            serversocket.setSoTimeout(10000);

            DataOutputStream out = new DataOutputStream(
                    serversocket.getOutputStream());
            out.flush();

            DataInputStream in = new DataInputStream(
                    serversocket.getInputStream());
            out.flush();
            String msg = "";

            msg = "hi";
            out.writeBytes(msg);
            out.flush();
            byte[] message = new byte[100];
            in.read(message);
            s1 = new String(message);
            Toast.makeText(getApplicationContext(), s1, Toast.LENGTH_LONG)
                    .show();

            ((TextView) findViewById(R.id.textView1)).setText(s1);
            in.close();
            out.close();
            serversocket.close();
        } catch (Exception e) {
            Toast.makeText(getApplicationContext(), String.valueOf(e),
                    Toast.LENGTH_LONG).show();
        }
        return null;
    }

    private class SendUserTask extends AsyncTask<Void, Void, String> {

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            Dialog = ProgressDialog.show(MainActivity.this, "",
                    "Logging In....", true);

            super.onPreExecute();
        }

        protected void onPostExecute(String s) {

            if (Dialog.isShowing())
                Dialog.dismiss();
        }

        @Override
        protected String doInBackground(Void... params) {
            // TODO Auto-generated method stub
            try {
                return sendreq();

            } catch (Exception e) {
                Toast.makeText(getApplicationContext(), String.valueOf(e),
                        Toast.LENGTH_SHORT).show();
            }
            return null;
        }
    }

}

Answer 1

this ((TextView) findViewById(R.id.textView1)).setText(s1); is executed from the background thread. you cannot access UI elements outside the UI thread.

You need to move that part to either onProgressUpdate or onPostExecute, or to run it in a runOnUiThread Runnable.