6 June 2024 Leave a comment Tech-Help
Handling the communication between activities in Android can be a common requirement. One effective method for achieving this is through the startActivityForResult approach. This allows one activity to start another and receive a result once the second activity finishes. However, with the recent updates in Android, this method has been deprecated in favor of a more streamlined approach. This guide will walk you through both the traditional and the new recommended methods.
Traditional Method: Using startActivityForResult
Step 1: Start the Second Activity
From your FirstActivity, call the SecondActivity using the startActivityForResult method:
int LAUNCH_SECOND_ACTIVITY = 1;
Intent i = new Intent(this, SecondActivity.class);
startActivityForResult(i, LAUNCH_SECOND_ACTIVITY);
Step 2: Set the Result in the Second Activity
In your SecondActivity, set the data which you want to return back to FirstActivity. If you don’t want to return any data, set a canceled result:
Intent returnIntent = new Intent();
returnIntent.putExtra("result", result);
setResult(Activity.RESULT_OK, returnIntent);
finish();
If you don’t want to return data:
Intent returnIntent = new Intent();
setResult(Activity.RESULT_CANCELED, returnIntent);
finish();
Step 3: Handle the Result in the First Activity
In your FirstActivity class, override the onActivityResult method to handle the result:
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
super.onActivityResult(requestCode, resultCode, data);
if (requestCode == LAUNCH_SECOND_ACTIVITY) {
if (resultCode == Activity.RESULT_OK) {
String result = data.getStringExtra("result");
// Handle the result
}
if (resultCode == Activity.RESULT_CANCELED) {
// Handle the case where there's no result
}
}
}
New Method: Using ActivityResultLauncher
With AndroidX, the startActivityForResult method has been deprecated. The new recommended approach is using ActivityResultLauncher and ActivityResultContracts.
Step 1: Register the Activity Result Launcher
Register the launcher in your activity:
ActivityResultLauncher launchSomeActivity = registerForActivityResult(
new ActivityResultContracts.StartActivityForResult(),
new ActivityResultCallback() {
@Override
public void onActivityResult(ActivityResult result) {
if (result.getResultCode() == Activity.RESULT_OK) {
Intent data = result.getData();
// Handle the result
}
}
}
);
Step 2: Launch the Second Activity
Use the launcher to start the second activity:
public void openYourActivity() {
Intent intent = new Intent(this, SecondActivity.class);
launchSomeActivity.launch(intent);
}
Step 3: Handle the Result
The result handling is done within the onActivityResult method as defined in the launcher registration.
Advantages of the New Approach
- Reduces complexity, especially when calling activities from fragments.
- Provides a more streamlined and type-safe way to handle results.
- Makes it easier to request permissions and handle callbacks.
Conclusion
Both methods allow for effective communication between activities. While the traditional startActivityForResult method is still widely used, transitioning to the new ActivityResultLauncher approach provides a more modern and efficient way to handle activity results.
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