Android: Implementing a Back Button from a class
Solution 1
Personally, I would suggest not doing this. I think overriding the back button in each Activity
would be safer, more flexible, and just as easy, if not easier. Chances are, you aren't always going to want to return to the MainActivity
as your app grows because its likely that this won't be the expected action for the users when they hit the back button. Override the back button in Activities
that need it and run your code
@Overrride
public void onBackPressed(View v) {
// save data first
Intent MainActivityIntent = new Intent(CurrentActivityName.this, MainActivityClass);
startActivity(MainActivityIntent);
super.onBackPressed();
}
You can also use flags such as FLAG_ACTIVITY_CLEAR_TOP
if you want to remove all Activities
between the current one and the target Activity
(here MainActivity
) by calling setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP)
Solution 2
There is a easier way to Listen to the backButton.
// Called when the activity has detected the user's press of the back key.
onBackPressed()
And when you do not call the super-method, there shouldn't be any further steps. But it is not a good way to "disable" the back-button.
http://developer.android.com/reference/android/app/Activity.html
Solution 3
There are multiple ways to block back button.
By overriding onKeyDown
or onBackPressed
of your Activity
.
Please visit following question link for detailed description and its solution given in answer.
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Ignasi Sánchez
Updated on July 12, 2022Comments
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Ignasi Sánchez almost 2 years
Okay, so here is my problem. I'm working on an android app and learning android at the same time, so most of the times I get errors. Normaly I can fix them after researching a bit, but I'm getting stuck in this point.
I'm trying to make a back button for every Activity in my app, so I thought about making a "BackButton" class, so I can instanciate it every time I want to. Here is my BackButton code:
import android.content.Intent; import android.view.View; import android.widget.Button; import android.app.Activity; public class BackButton extends Activity implements View.OnClickListener{ public static Button BackButton; // Defining the button public BackButton() { BackButton = (Button) findViewById(R.id.bBack); BackButton.setOnClickListener(this); } //To get the Button public static Button getBackButton() { return BackButton; } // OnClickListener public void onClick(View v) { try { Class MainActivityClass = Class.forName("eu.lafarga.treballderecerca.MainActivity"); Intent MainActivityIntent = new Intent(BackButton.this, MainActivityClass); startActivity(MainActivityIntent); } catch (ClassNotFoundException e) { e.printStackTrace(); }finally { // Save the things we've done. } } }
So, how should I implement this in any activity? I'm doind something wrong? (Sure I'm lol)