How can I detect screen rotation?

Question

is it possible to detect screen rotation? I mean - rotation only, which is clearly distinguishable from activity initialization from another activity?

The onXxx meth

Answer 1

Use onConfigurationChanged method to detect the screen rotation isn't good idea. Configuration Change in this activity wouldn't works correctly when user rotate the screen.

So I use this solution to solve this problem.

public class SampleActivity extends AppCompatActivity {
    public static final String KEY_LAST_ORIENTATION = "last_orientation";
    private int lastOrientation;

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

        if (savedInstanceState == null) {
            lastOrientation = getResources().getConfiguration().orientation;
        }
    }

    @Override
    protected void onStart() {
        super.onStart();
        checkOrientationChanged();
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        lastOrientation = savedInstanceState.getInt(KEY_LAST_ORIENTATION);
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(KEY_LAST_ORIENTATION, lastOrientation);
    }

    private void checkOrientationChanged() {
        int currentOrientation = getResources().getConfiguration().orientation;
        if (currentOrientation != lastOrientation) {
            onScreenOrientationChanged(currentOrientation);
            lastOrientation = currentOrientation;
        }
    }

    public void onScreenOrientationChanged(int currentOrientation) {
        // Do something here when screen orientation changed
    }
}

But code still not good enough to use it in my project, so I applied this code to my own library (https://github.com/akexorcist/ScreenOrientationHelper).

compile 'com.akexorcist:screenorientationhelper:'

You can create base activity class like this

    public class BaseActivity extends AppCompatActivity implements ScreenOrientationHelper.ScreenOrientationChangeListener {
    private ScreenOrientationHelper helper = new ScreenOrientationHelper(this);

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        helper.onCreate(savedInstanceState);
        helper.setScreenOrientationChangeListener(this);
    }

    @Override
    protected void onStart() {
        super.onStart();
        helper.onStart();
    }

    @Override
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        helper.onSaveInstanceState(outState);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        helper.onRestoreInstanceState(savedInstanceState);
    }

    @Override
    public void onScreenOrientationChanged(int orientation) {

    }
}

Then extend the activity with this base class

public class MainActivity extends BaseActivity {

    ...

    @Override
    public void onScreenOrientationChanged(int orientation) {
        // Do something when screen orientation changed
    }
}

Done!