ANDROID Recieve message that another activity is destroyed

Question

I have simple app with 2 activities. One of them is transparent. All process looks like :

1) I lunch my app, at start displayed is my MainActivity

2) I click button "show transparent activity" and after that displayed is my TransparentActivity (under it still a little bit visible is my MainActivity)

3) I click button "Close transparent Activity" after that my TransparentActivity is closed(killed/destroyed) and after that I create and display Dialog (above my MainActivity).

I have problem with last point (3) how I should build and display this dialog exactly after close TransparentActivity ? How I should close this Transparent app ? should I just finish() it or maybe build intent to MainActivity ?

Answer 1

You should use startActivityForResult method.

For your particular case you could implement something like this:

MainActivity.java

public class MainActivity extends AppCompatActivity {
    private static int REQUEST_CODE = 1234;

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

        final Button btnShowTransparencyActivity = (Button) findViewById(R.id.button);
        btnShowTransparencyActivity.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(final View view) {
                final Intent intent = new Intent(MainActivity.this, TransparentActivity.class);
                startActivityForResult(intent, REQUEST_CODE);
            }
        });
    }

    @Override
    protected void onActivityResult(final int requestCode, final int resultCode, Intent intent) {
        if (REQUEST_CODE == requestCode) {
            if (resultCode == Activity.RESULT_OK) {
                Toast.makeText(this, "Show dialog", Toast.LENGTH_SHORT).show();
            } else if (resultCode == Activity.RESULT_CANCELED) {
                Toast.makeText(this, "Don't show dialog", Toast.LENGTH_SHORT).show();
            }
        }
    }

}

TransparentActivity.java

public class TransparentActivity extends AppCompatActivity {

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

        final Button btnCloseTransparentActivity = (Button) findViewById(R.id.button);
        btnCloseTransparentActivity.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(final View view) {
                final Intent intent = new Intent();
                setResult(Activity.RESULT_OK, intent);
                finish();
            }
        });
    }

    @Override
    public void onBackPressed() {
        final Intent intent = new Intent();
        setResult(Activity.RESULT_CANCELED, intent);
        super.onBackPressed();
    }
}