On Back press method with different layouts

Question

I have a single activity which has two buttons on it .each button opens a new layout .now if i will press back my application will close .but i want to return on Mainactivity and if the user presses back again then app is closed and if he does not press and goes to the second layout and press back then app should not get closed. the condition should be if the user is on Mainactivity and he presses back button then the application closes. I came up with an idea on onBackPress method if i could set this condition

if (k==1 && Its not a Mainactivity(or the user is not inside a Mainactivity)) {//I dont know how to check for that 

    Intent i = new Intent(this,Mainactivity.class);
    startActivity(i);
    this.finish();
} else if (k==1 && Its a Mainactivity(or the user is inside a Mainactivity)) { 
  this.finish(); //then i just want to close the application,I dont know this.finish() ,It does not close the app but still it runs in background 
}

If u guys want to see my code here it is a simple example of what i am trying to achieve:-

public class MainActivity extends AppCompatActivity {

    Button btn1,button2;              //Creating button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {

           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
           btn1= (Button)findViewById(R.id.btn1);      //finding button1
           button2=(Button)findViewById(R.id.button2); //finding button2 
           btn1.setOnClickListener(new View.OnClickListener() {

             @Override
             public void onClick(View v) {

               setContentView(R.layout.btn1);           

            }
        });


 button2.setOnClickListener(new View.OnClickListener() {

    @Override
    public void onClick(View v) {

         setContentView(R.layout.btn2);
      }
  });

  }
}

Please help me.

Answer 1

In onBackPressed(), just check the value of k. If the value of k is 1 or 2, then call setContentView(R.layout.activity_main) again to show the main layout otherwise call super.onBackPressed() to close the MainActivity.

You need to call method initializeButtons() every time after setting activity_main layout to get the reference of buttons from layout as well as adding onClick listeners.

TRY THIS:

public class MainActivity extends AppCompatActivity {

    Button button1, button2;

    int k = 0;

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

        initializeButtons();
    }

    public void initializeButtons() {
        button1 = (Button) findViewById(R.id.btn1);
        button2 = (Button) findViewById(R.id.button2); 

        button1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                k = 1;
                setContentView(R.layout.btn1);           
            }
        });

        button2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                k = 2;
                setContentView(R.layout.btn2);
            }
        });
    }

    @Override
    public void onBackPressed() {

        if (k == 1 || k == 2) {
            k = 0;
            setContentView(R.layout.activity_main);
            initializeButtons();
        } else {
            super.onBackPressed();
        }
    }
}

UPDATE:
As per discussion in comment section, If you want to open Mainctivity again during back press, then override and update onBackPressed() as below:

    @Override
    public void onBackPressed() {

        if (k == 1 || k == 2) {
            k = 0;

            Intent i = new Intent(this, MainActivity.class);
            startActivity(i);
        } else {
            super.onBackPressed();
        }
    }

Hope this will help~