@Override
 public void onBackPressed() {
        super.onBackPressed();
        finish();


    }
}

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

ActivityCompat.finishAffinity(Youractivity.this);
finish();

/**
     * This method is use to handle back key event
     */
    public boolean onKeyDown(int keyCode, KeyEvent event)
    {
        if (keyCode == KeyEvent.KEYCODE_BACK)
        {
            finish();
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }