Android Studio with libGDX doesn't recognize boolean

Question

In my game, when the users clicks an image button, the value of a boolean changes and then the game is closed. I mean, if I want to restart the game, I click this image button, the game is closed and immediately is opened. However this doesn't happen because the value of the boolean is false and I don't know why at all.

Here is the code of the image-button:

    playagain.addListener(new ClickListener()
    {
        @Override
        public void clicked(InputEvent event, float x, float y)
        {
            interfaccia.rigioca();
            Gdx.app.exit();
        }
    });

And this is the code of the MainActivity:

public class MainActivity extends Activity implements MyGdxGame.GestioneClick, Serializable
{
MainActivity activity;
boolean start;
@Override
public void onCreate(final Bundle bundle)
{
    super.onCreate(bundle);
    setContentView(R.layout.layout);
    activity = this;
    findViewById(R.id.button).setOnClickListener(new View.OnClickListener()
    {
        @Override
        public void onClick(View v)
        {
            startActivity();
        }
    });

}

@Override
public void onResume()
{
    super.onResume();
    if(start)
        startActivity();
}

@Override
public void menu()
{
    start=false;
}

@Override
public void rigioca()
{
    start=true;
}

public void startActivity()
{
    Intent intent = new Intent(MainActivity.this,AndroidLauncher.class);
    intent.putExtra("MainActivity",activity);
    activity.startActivity(intent);
}

}

As you can see, rigioca method is called and start sould be true. I checked ALL with logs and we can say that the value is true. Then resume method is called but start value is false! How is it possible? I also took away start=false; in menu method, but that isn't the problem. Why is this variable false!?

Note: onDestroy and onCreate aren't called but the activity is destroyed.

Answer 1

(from chat)

You should not be restarting your entire program when you wish to restart your game. Instead reset the variables that control your game to their original state.

Take this game as an example:

In this example I reset the player's health (top left), the level (top right), and the abilities (bottom right) whenever the player pushes my 'reset' button.

The code looks something like this:

gameOver = false; 
handler.clear(); 
director.reset(); 
level = 0; 
timer = 0; 
enemies = null;
shields = 0;
teleports = 0;

I simply reset all of the variables to what they were when the game started :)