Trying to create a Login app in Android using HTTPPost and HTTPGet but Login has stopped

Question

    package com.example.login;

    import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.io.UnsupportedEncodingException;
    import java.util.ArrayList;
    import java.util.List;

    import org.apache.http.HttpResponse;
    import org.apache.http.NameValuePair;
    import org.apache.http.client.HttpClient;
    import org.apache.http.client.entity.UrlEncodedFormEntity;
    import org.apache.http.client.methods.HttpPost;
    import org.apache.http.impl.client.DefaultHttpClient;
    import org.apache.http.message.BasicNameValuePair;

    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.support.v7.app.ActionBarActivity;
    import android.view.LayoutInflater;
    import android.view.Menu;
    import android.view.MenuItem;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.EditText;
    import android.widget.Toast;

    public class Testcase extends ActionBarActivity {
    EditText user;
    EditText pass;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_testcase);
        user = (EditText) this.findViewById(R.id.editText1);
        pass = (EditText) this.findViewById(R.id.editText2);


    }

    //When login button is pressed
    public void xxx(View view) {
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost(
                "http://www.masterkool.com/callcenter/index.php");
        List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
        nameValuePairs.add(new BasicNameValuePair("a_user", user.getText()
                .toString()));
        nameValuePairs.add(new BasicNameValuePair("a_pass", pass.getText()
                .toString()));

        try {

            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse execute = httpclient.execute(httppost);
            InputStream content;
            content = execute.getEntity().getContent();
            BufferedReader buffer = new BufferedReader(new InputStreamReader(
                    content));
            String s = "";
            String test = "";
            while ((s = buffer.readLine()) != null) {
                test += s;
            }
            if (test.contains("U")) {
                // reset field and toast
                Toast.makeText(getBaseContext(), "Login Failed",     Toast.LENGTH_SHORT)
                        .show();
            } else {
                // Intent intent = new Intent(MainActivity.this,Form.class);
                // this.startActivity(intent);
                Toast.makeText(getBaseContext(), "Login Successful",
                        Toast.LENGTH_SHORT).show();
            }
        } catch (IllegalStateException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.testcase, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

A placeholder fragment containing a simple view.

Here is the logcat:

 06-10 13:42:29.670: E/AndroidRuntime(797): FATAL EXCEPTION: main
06-10 13:42:29.670: E/AndroidRuntime(797): Process: com.example.login,
PID: 797 06-10 13:42:29.670: E/AndroidRuntime(797):
java.lang.IllegalStateException: Could not execute method of the
activity 06-10 13:42:29.670: E/AndroidRuntime(797):     at
android.view.View$1.onClick(View.java:3823) 06-10 13:42:29.670:
E/AndroidRuntime(797):  at
android.view.View.performClick(View.java:4438) 06-10 13:42:29.670:
E/AndroidRuntime(797):  at
android.view.View$PerformClick.run(View.java:18422) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
android.os.Handler.handleCallback(Handler.java:733) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
android.os.Handler.dispatchMessage(Handler.java:95) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
android.os.Looper.loop(Looper.java:136) 06-10 13:42:29.670:
E/AndroidRuntime(797):  at
android.app.ActivityThread.main(ActivityThread.java:5017) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
java.lang.reflect.Method.invokeNative(Native Method) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
java.lang.reflect.Method.invoke(Method.java:515) 06-10 13:42:29.670:
E/AndroidRuntime(797):  at
com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
06-10 13:42:29.670: E/AndroidRuntime(797):  at
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
dalvik.system.NativeStart.main(Native Method) 06-10 13:42:29.670:
E/AndroidRuntime(797): Caused by:
java.lang.reflect.InvocationTargetException 06-10 13:42:29.670:
E/AndroidRuntime(797):  at
java.lang.reflect.Method.invokeNative(Native Method) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
java.lang.reflect.Method.invoke(Method.java:515) 06-10 13:42:29.670:
E/AndroidRuntime(797):  at android.view.View$1.onClick(View.java:3818)
06-10 13:42:29.670: E/AndroidRuntime(797):  ... 11 more 06-10
13:42:29.670: E/AndroidRuntime(797): Caused by:
android.os.NetworkOnMainThreadException 06-10 13:42:29.670:
E/AndroidRuntime(797):  at
android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1145)
06-10 13:42:29.670: E/AndroidRuntime(797):  at
java.net.InetAddress.lookupHostByName(InetAddress.java:385) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
java.net.InetAddress.getAllByNameImpl(InetAddress.java:236) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
java.net.InetAddress.getAllByName(InetAddress.java:214) 06-10
13:42:29.670: E/AndroidRuntime(797):    at
org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
06-10 13:42:29.670: E/AndroidRuntime(797):  at
org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
06-10 13:42:29.670: E/AndroidRuntime(797):  at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
06-10 13:42:29.670: E/AndroidRuntime(797):  at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
06-10 13:42:29.670: E/AndroidRuntime(797):  at
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
06-10 13:42:29.670: E/AndroidRuntime(797):  at
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
06-10 13:42:29.670: E/AndroidRuntime(797):  at
org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
06-10 13:42:29.670: E/AndroidRuntime(797):  at
com.example.login.Testcase.xxx(Testcase.java:57) 06-10 13:42:29.670:
E/AndroidRuntime(797):  ... 14 more

Answer 1

Webservices calls tend to consume time which blocks the UI thread and hence should not be called from the main thread. Webservice calls as best practice should always be called only from an AsyncTask.

Below is untested code. Hope you get a fair idea of AsyncTask with this code.

public class MainActivity extends Activity
{   
@Override
protected void onCreate(Bundle savedInstanceState) 
{
    .... // Some code here
    // Async task can also be called from within an onclick code.
    new AsyncTaskOperation().execute("");
}


/* Async Task called to avoid Android Network On Main Thread Exception. Web services need to be consumed only in background.     */
private class AsyncTaskOperation extends AsyncTask <String, Void, Void>
{

    private ProgressDialog Dialog = new ProgressDialog(LoginActivity.this);
     String ciao="";
    protected void onPreExecute() {
        // Display the loading spinner
        Dialog.setMessage("Loading... Please wait.. ");
        Dialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        Dialog.setInverseBackgroundForced(false);
        Dialog.setCancelable(false);
        Dialog.setIndeterminateDrawable(getResources().getDrawable(R.drawable.progressbar_new));

        Dialog.show();
    }

    @Override
    protected Void doInBackground(String... paramsObj) {
       HttpClient httpclient = new DefaultHttpClient();
    HttpPost httppost = new HttpPost(
            "http://www.masterkool.com/callcenter/index.php");
    List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
    nameValuePairs.add(new BasicNameValuePair("a_user", user.getText()
            .toString()));
    nameValuePairs.add(new BasicNameValuePair("a_pass", pass.getText()
            .toString()));

    try {

        httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
        HttpResponse execute = httpclient.execute(httppost);
        InputStream content;
        content = execute.getEntity().getContent();
        BufferedReader buffer = new BufferedReader(new InputStreamReader(
                content));
        String s = "";
        String test = "";
        while ((s = buffer.readLine()) != null) {
            test += s;
        }
        if (test.contains("U")) {
            // reset field and toast
            Toast.makeText(getBaseContext(), "Login Failed",     Toast.LENGTH_SHORT)
                    .show();
        } else {
            // Intent intent = new Intent(MainActivity.this,Form.class);
            // this.startActivity(intent);
            Toast.makeText(getBaseContext(), "Login Successful",
                    Toast.LENGTH_SHORT).show();
        }
    } catch (IllegalStateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
        return null;
    }

    protected void onPostExecute(Void unused) 
    {
        // Close progress dialog
        Dialog.dismiss();
        // Do actions after end of the HTTPGet or POST Method

    } // End of method onPostExecute

} // End of class AsyncTaskOperation

} End of MainActivity