如何检查android是否要重新创建活动或销毁？

Question

I have an android studio project. When I am rotating screen, android destroys and recreates main activity. How can I check during the destruction, if android going to recreate activity?

Answer 1

You can determine if the activity is finishing by user choice (user chooses to exit by pressing back for example) using isFinishing() in onDestroy .

  @Override
  protected void onDestroy() {
    super.onDestroy();
    if (isFinishing()) {
      // wrap stuff up
    } else { 
      //It's an orientation change.
    }
  }

Another alternative (if you're only targeting API>=11) is isChangingConfigurations .

  @Override
  protected void onDestroy() {
    super.onDestroy();
    if (isChangingConfigurations()) {
      //It's an orientation change.
    }
  }

Answer 2

Override the Activity lifecycle methods to see the flow.And then use the appropriate method to check activity current state like isChangingConfigurations() Example code snippet.

MainActivity.java

public class MainActivity extends AppCompatActivity {

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

    @Override
    protected void onStart() {
        super.onStart();
        Log.i(MainActivity.class.getSimpleName(),"OnStart Called");
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Log.i(MainActivity.class.getSimpleName(),"OnRestart Called");
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        Log.i(MainActivity.class.getSimpleName(),"OnDestroy Called");
    }


    @Override
    protected void onPause() {
        super.onPause();
        Log.i(MainActivity.class.getSimpleName(),"OnPause Called");
    }

   @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        Log.i(MainActivity.class.getSimpleName(),"OnConfiguration Changed Called");
    }

}

For more details see the official page activity-lifecycle