How can I call OnDestroy() when I press BackButton while I'm on First Activity?

Question

There are two activities in my app. I want to perform a simple function. In Second Activity, If button is clicked it should hide and go back to First Activity And If I click the button in First Activity the Second Activity should be open with hidden button. I've achieved this by below code.

But the problem is. I can't close (call onDestroy())the app when I press back button while I'm in First Activity. The back button performs switch between two activities.

First Activity Java:

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class first extends AppCompatActivity {

    Button btn1;

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

        btn1 = (Button) findViewById(R.id.btn1);

        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {


                Intent intent = new Intent(first.this, second.class);
                startActivity(intent);


            }
        });
    }
    public void onBackPressed() {
        super.onBackPressed();
    }
}

Second Activity Java:

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;

public class second extends AppCompatActivity {

    Button btn2;   

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


        onBackPressed();
        btn2 = (Button) findViewById(R.id.btn2);

        btn2.setOnClickListener(new View.OnClickListener() {


            @Override
            public void onClick(View v) {

                btn2.setVisibility(View.GONE);
                Intent intent = new Intent(second.this, first.class);
                intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                startActivity(intent);

            }
        });
    }

    public void onBackPressed() {
        intent = new Intent(second.this, first.class);
        intent.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
        startActivity(intent);
    }
}

How can I call OnDestroy() in this Condition?

Answer 1

The reason is you override onBackPressed() in the second activity. So that means everytime you press the back button on your second activity, it will create a new first activity instead return to the old one. The app will stuck in this loop. Try to remove onBackPressed method on second activity or call finish() in it.

Answer 2

Call finish() from the back pressed event. Override the backpressed event so you can customise it.

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

Answer 3

You can use this onBackPress() method like this in first activity

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

OR

you can just delete onBackPress() because you don't have to override it.