我应该在哪里放置意图代码？

Question

Following are the .java files I had written to login to the app using mysql. I had found help on http://easyway2in.blogspot.in/2015/07/android-mysql-database-connect.html

MainActivity.java

package com.example.soumya.attendance;

import android.app.Activity;
import android.content.Intent;
import android.os.StrictMode;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
public class MainActivity extends Activity{
    EditText ET_NAME,ET_PASS;
    String login_name,login_pass;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        ET_NAME = (EditText)findViewById(R.id.editText1);
        ET_PASS = (EditText)findViewById(R.id.editText2);
    }
    public void userLogin(View view)
    {
        login_name = ET_NAME.getText().toString();
        login_pass = ET_PASS.getText().toString();
        String method = "login";
        BackgroundTask backgroundTask = new BackgroundTask(this);
        backgroundTask.execute(method,login_name,login_pass);
    }
    @Override
    public void onBackPressed() {
        return;
    }
}

BackgroundActivity.java

    package com.example.soumya.attendance;
        import android.app.AlertDialog;
        import android.content.Context;
        import android.content.Intent;
        import android.os.AsyncTask;
        import android.widget.Toast;
        import java.io.BufferedReader;
        import java.io.BufferedWriter;
        import java.io.IOException;
        import java.io.InputStream;
        import java.io.InputStreamReader;
        import java.io.OutputStream;
        import java.io.OutputStreamWriter;
        import java.net.HttpURLConnection;
        import java.net.MalformedURLException;
        import java.net.URL;
        import java.net.URLEncoder;
public class BackgroundTask extends AsyncTask<String,Void,String> {
    AlertDialog alertDialog;
    Context ctx;
    BackgroundTask(Context ctx)
    {
        this.ctx =ctx;
    }
    @Override
    protected void onPreExecute() {
        alertDialog = new AlertDialog.Builder(ctx).create();
        alertDialog.setTitle("Login Information....");
    }
    @Override
    protected String doInBackground(String... params) {
        String reg_url = "http://10.0.2.2/webapp/register.php";
        String login_url = "http://10.0.2.2/login.php";
        String method = params[0];
        if (method.equals("register")) {
            String name = params[1];
            String user_name = params[2];
            String user_pass = params[3];
            try {
                URL url = new URL(reg_url);
                HttpURLConnection httpURLConnection = (HttpURLConnection) url.openConnection();
                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoOutput(true);
                //httpURLConnection.setDoInput(true);
                OutputStream OS = httpURLConnection.getOutputStream();
                BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(OS, "UTF-8"));
                String data = URLEncoder.encode("user", "UTF-8") + "=" + URLEncoder.encode(name, "UTF-8") + "&" +
                        URLEncoder.encode("user_name", "UTF-8") + "=" + URLEncoder.encode(user_name, "UTF-8") + "&" +
                        URLEncoder.encode("user_pass", "UTF-8") + "=" + URLEncoder.encode(user_pass, "UTF-8");
                bufferedWriter.write(data);
                bufferedWriter.flush();
                bufferedWriter.close();
                OS.close();
                InputStream IS = httpURLConnection.getInputStream();
                IS.close();
                //httpURLConnection.connect();
                httpURLConnection.disconnect();
                return "Registration Success...";
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        else if(method.equals("login"))
        {
            String login_name = params[1];
            String login_pass = params[2];
            try {
                URL url = new URL(login_url);
                HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
                httpURLConnection.setRequestMethod("POST");
                httpURLConnection.setDoOutput(true);
                httpURLConnection.setDoInput(true);
                OutputStream outputStream = httpURLConnection.getOutputStream();
                BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
                String data = URLEncoder.encode("login_name","UTF-8")+"="+URLEncoder.encode(login_name,"UTF-8")+"&"+
                        URLEncoder.encode("login_pass","UTF-8")+"="+URLEncoder.encode(login_pass,"UTF-8");
                bufferedWriter.write(data);
                bufferedWriter.flush();
                bufferedWriter.close();
                outputStream.close();
                InputStream inputStream = httpURLConnection.getInputStream();
                BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream,"iso-8859-1"));
                String response = "";
                String line = "";
                while ((line = bufferedReader.readLine())!=null)
                {
                    response+= line;
                }
                bufferedReader.close();
                inputStream.close();
                httpURLConnection.disconnect();
                return response;
            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    @Override
    protected void onProgressUpdate(Void... values) {
        super.onProgressUpdate(values);
    }
    @Override
    protected void onPostExecute(String result) {
        if(result.equals("Registration Success..."))
        {
            Toast.makeText(ctx, result, Toast.LENGTH_LONG).show();
        }
        else
        {
            alertDialog.setMessage(result);
            alertDialog.show();
            }
        }
    }

Now, I want to add an intent code so that if the user logs in successfully, he/she will be taken to the other activity. But, if I try to place it in MainActivity.java, it does not check for successful login or not. Please help me with it. Many others also have the same question on the source. Here, my login.php returns a result to notify whether the login is successful or not through echo.

Answer 1

Its Simple,

Just place on the Intent code on Post Execute when the login Success

@Override
    protected void onPostExecute(String result) {
        if(result.equals("Registration Success..."))
        {
            Toast.makeText(ctx, result, Toast.LENGTH_LONG).show();

        //Place the Intent Code Here.

        Intent intent = new Intent("android.intent.category.LAUNCHER");
        intent.setClassName("com.your.package","com.your.package.MainActivity");
        intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        startActivity(intent);

        }
        else
        {
            alertDialog.setMessage(result);
            alertDialog.show();
            }
        }

Happy Coding :)