Understanding onCreate() After finish() in onStop()
The Scenario:
In Android development, we often encounter situations where we need to close an activity using `finish()` within the `onStop()` lifecycle method. This can lead to unexpected behavior, especially when the activity is recreated due to configuration changes (e.g., screen rotation). The key question arises: **Will the activity’s `onCreate()` be called again after we call `finish()` in `onStop()`?**
The Answer:
In most cases, **No, `onCreate()` will not be called again after `finish()` in `onStop()`**. This is because `finish()` effectively removes the activity from the activity stack. Once an activity is finished, it no longer exists, and there’s no reason to recreate it.
Key Considerations:
– **Activity State:** The activity’s state, such as saved instance state, is lost when `finish()` is called.
– **Configuration Changes:** If the activity is destroyed due to configuration changes and `finish()` is called in `onStop()`, it won’t be recreated.
– **Explicit Recreating:** Calling `recreate()` after `finish()` within `onStop()` will trigger a new `onCreate()` call, but this is not the standard behavior.
Consequences of Using finish() in onStop():
– **Data Loss:** Any data not saved before calling `finish()` will be lost.
– **Unexpected Behavior:** The activity’s lifecycle methods might not be called as expected, potentially causing issues with data persistence and UI updates.
Best Practices:
– **Use `finish()` in `onDestroy()`:** This ensures the activity is completely removed from the stack and its resources are released.
– **Handle Configuration Changes:** Use `onSaveInstanceState()` and `onRestoreInstanceState()` to persist data during configuration changes.
– **Avoid Complex Scenarios:** If you need to handle intricate scenarios where an activity might be finished in `onStop()`, consider alternatives like using fragments or a different approach altogether.
Example Scenario and Code:
“`java
// Activity.java
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d(“MainActivity”, “onCreate called”);
}
@Override
protected void onStop() {
super.onStop();
Log.d(“MainActivity”, “onStop called”);
finish(); // Call finish() here
}
@Override
protected void onDestroy() {
super.onDestroy();
Log.d(“MainActivity”, “onDestroy called”);
}
}
“`
“`
// Output in the Logcat:
D/MainActivity: onCreate called
D/MainActivity: onStop called
D/MainActivity: onDestroy called
“`
**Explanation:**
– In this example, we call `finish()` in the `onStop()` method.
– As expected, `onCreate()` is not called again after `finish()`.
– The activity goes through `onStop()` and then directly to `onDestroy()`, confirming its complete removal.
Summary:
While calling `finish()` in `onStop()` might seem convenient in certain situations, it’s generally not recommended due to the consequences and potential for unexpected behavior. Using `finish()` in `onDestroy()` is the preferred approach to ensure proper activity lifecycle management.
Table for Comparison:
| Method | Activity State | `onCreate()` Called Again? | Comments |
| ————– | ——————- | —————————– | ———– |
| `finish()` in `onStop()` | Destroyed | No | Activity is removed from the stack. |
| `finish()` in `onDestroy()` | Destroyed | No | Recommended for complete removal. |
| `recreate()` after `finish()` in `onStop()` | Recreated | Yes | Not the standard behavior. |