How to close an Activity(remove from Foreground)?

Question

I have the following code in my Mainactivity class that has a Alertdialog and processing in the onClick method():

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.DialogInterface.OnClickListener;
import android.os.Bundle;

public class MainActivity extends Activity implements OnClickListener{

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

        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle("Você deseja sair da aplicação?")
                .setPositiveButton("OK", this)
                .setNegativeButton("Cancelar", this);
        Dialog dialog = builder.create();
        dialog.show();
    }

    @Override
    public void onClick(DialogInterface dialog, int which) {
        switch (which) {
        case DialogInterface.BUTTON_POSITIVE:
            dialog.cancel();
            finish();
            break;
        case DialogInterface.BUTTON_NEGATIVE:
            break;
        default:
            break;
        }

    }
}

Manifest:

<uses-sdk
    android:minSdkVersion="14"
    android:targetSdkVersion="20" />

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".MainActivity"
        android:label="@string/title_activity_main" >

        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

I want to close Activity completely without staying in the Foreground, but the application still follows the image below when I press the button marked red:

Answer 1

This area that is showing in the image is the Recents Screen. When an app appears there, it is not necessarily on foreground, but it was recently used, possibly closed (as is your case).

You can control the appearance of your app on Recents Screen, simply use the attribute android:excludeFromRecents in the statement of Activity Launcher. With this, your app will never appear on Recents Screen, nor when going to the background by the button Home.

To use just set it in your Activity:

<activity
    android:name=".MainActivity"
    android:label="@string/title_activity_main"
    android:excludeFromRecents="true">

    <intent-filter>
        <action android:name="android.intent.action.MAIN" />

        <category android:name="android.intent.category.LAUNCHER" />
    </intent-filter>
</activity>

For more details, just go to documentation of this attribute.

Answer 2

in this code the Activity will be closed as soon as you exit it or open another Activity

Overwrite the Activity onPause() method

protected void onPause() {
    // TODO Auto-generated method stub
    super.onPause();
    finish();
}