How to start new intent from PostExecute in Android?

Question

Here is the code I'm working on. When I'm running my app with this code, it's getting stopped, with no errors.

I have changed manifest.xml, but it's not working.

public class MainActivity extends Activity {
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ok=(Button)findViewById(R.id.Button01);  
        ok.setOnClickListener(new View.OnClickListener() {  
            public void onClick(View arg0) { 
                new jsdetails().execute();


                }

        });
    }
    public class jsdetails extends AsyncTask<String,String,String> {

        Boolean validUser = false;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setMessage("Verifying.. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }
        protected String doInBackground(String... args) {

            //int valoreOnPostExecute = 0;
            error=(TextView)findViewById(R.id.TextView01);
            un=(EditText)findViewById(R.id.EditText01);  
            pw=(EditText)findViewById(R.id.EditText02); 

            params.add(new BasicNameValuePair("JS_Email",un.getText().toString()));  
            params.add(new BasicNameValuePair("JS_Password",pw.getText().toString()));

            JSONObject json = jParser.makeHttpRequest(url,"POST",params); 
            Log.d("All Products: ", json.toString());
                try {  
             int success = json.getInt(TAG_SUCCESS);
                                 if (success == 1)
                 {
                     validUser = true;

                 }
                                } catch (JSONException e) {
                e.printStackTrace();
            }
                 return null;
        }
        protected void onPostExecute(String file_url) {

            pDialog.dismiss();
            if(validUser)
            {
                Intent i = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(i);
                finish();
            }


             params.clear();
                }
            }

} 

Answer 1

You must make view action on UIThread. Async doInBackground method on background thread. You don't get editText' s text in background thread.

Answer 2

Try this.. Remove the finish();

if(validUser)
{
      Intent i = new Intent(MainActivity.this, UserManage.class);
      startActivity(i);
}

Answer 3

You are returning null in doinbackground() method instead return valid user and in onPostExecute

protected void onPostExecute(String validUser) {

        pDialog.dismiss();
        if(validUser)
        {
            Intent i = new Intent(getApplicationContext(), MainActivity.class);
            startActivity(i);
            finish();
        }


         params.clear();
            }
        }

Answer 4

Do it like this

 public class jsdetails extends AsyncTask<String,String,Boolean> {

        Boolean validUser = false;
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setMessage("Verifying.. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }
        protected Boolean doInBackground(String... args) {

            //int valoreOnPostExecute = 0;
            error=(TextView)findViewById(R.id.TextView01);
            un=(EditText)findViewById(R.id.EditText01);  
            pw=(EditText)findViewById(R.id.EditText02); 

            params.add(new BasicNameValuePair("JS_Email",un.getText().toString()));  
            params.add(new BasicNameValuePair("JS_Password",pw.getText().toString()));

            JSONObject json = jParser.makeHttpRequest(url,"POST",params); 
            Log.d("All Products: ", json.toString());
                try {  
             int success = json.getInt(TAG_SUCCESS);
                                 if (success == 1)
                 {
                     validUser = true;

                 }
                                } catch (JSONException e) {
                e.printStackTrace();
            }
                 return validUser;
        }
        protected void onPostExecute(Boolean validUser) {

            pDialog.dismiss();
            if(validUser)
            {
                Intent i = new Intent(getApplicationContext(), MainActivity.class);
                startActivity(i);
                finish();
            }


             params.clear();
                }
            }

}***

Answer 5

I made a few changes and suggestions. Refer following code.

public class MainActivity extends Activity {
protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
            error=(TextView)findViewById(R.id.TextView01);
            un=(EditText)findViewById(R.id.EditText01);      // Note
            pw=(EditText)findViewById(R.id.EditText02);
        ok=(Button)findViewById(R.id.Button01);  
        ok.setOnClickListener(new View.OnClickListener() {  
            public void onClick(View arg0) { 
                new jsdetails(MainActivity.this).execute(un.getText().toString(),pw.getText().toString());
// Note

                }

        });
    }
    public class jsdetails extends AsyncTask<String,Integer,Boolean > {    // Note
        Context context;    // Note
        Boolean validUser = false;
        jsdetails(Context context){    // Note
           this.context=context;
        }
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(MainActivity.this);
            pDialog.setMessage("Verifying.. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }
        protected Boolean doInBackground(String... args) {    // Note

            //int valoreOnPostExecute = 0;


            params.add(new BasicNameValuePair("JS_Email",args[0]));      // Note
            params.add(new BasicNameValuePair("JS_Password",args[1]));

            JSONObject json = jParser.makeHttpRequest(url,"POST",params); 
            Log.d("All Products: ", json.toString());
                try {  
             int success = json.getInt(TAG_SUCCESS);
                                 if (success == 1)
                 {
                     validUser = true;

                 }
                                } catch (JSONException e) {
                e.printStackTrace();
            }
                 return validUser ;
        }
        protected void onPostExecute(String result) {

            pDialog.dismiss();
            if(result)    // Note
            {
                Intent i = new Intent(context, UserManage.class);    // Note
                startActivity(i);
                finish();
            }


             params.clear();
                }
            }

}