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I have a activity which stores certain data, and when the user presses the back button (Avd Hardware Button, for example), the application does not return to the previous screen, but rather open a dialog screen asking if the user wants to return to the previous screen knowing that it will lose the saved data.
How to capture this event?
3
Try using this code:
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
//Handle the back button
if(keyCode == KeyEvent.KEYCODE_BACK) {
//Ask the user if they want to quit
new AlertDialog.Builder(this)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle(R.string.quit)
.setMessage(R.string.really_quit)
.setPositiveButton(R.string.yes, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
//Stop the activity
YourClass.this.finish();
}
})
.setNegativeButton(R.string.no, null)
.show();
return true;
}
else {
return super.onKeyDown(keyCode, event);
}
}
Or this for Android 2.0+
@Override
public void onBackPressed() {
new AlertDialog.Builder(this)
.setIcon(android.R.drawable.ic_dialog_alert)
.setTitle("Closing Activity")
.setMessage("Are you sure you want to close this activity?")
.setPositiveButton("Yes", new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which) {
finish();
}
})
.setNegativeButton("No", null)
.show();
}
I wouldn’t even consider the first option. Apps below 2.2 don’t even have access to the play store.
But you can still install APK’s by transfer.
Yes, but if someone has an appliance running Eclair, sell it to the museum for cash :)
JP worked perfectly the second way, thank you very much!
3
A little Google gave me the following result:
public boolean onKeyDown(int keyCode, KeyEvent event) {
if(keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0){
return true;
}
return super.onKeyDown(keyCode, event);
}
It only checks if the keyevent is equal to the given keycode! Remembering that if you format a little, you can use the code to detect any keypress!
(source: http://nisha113a5.blogspot.com.br/2012/01/intercept-home-key-android.html)
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The title of your question is different from the body of the question. In the first you are asking about UX, and in the second about programming.
– Emerson Rocha
Just commenting that this is not a recommended practice on the Android platform. The back button should ALWAYS return immediately. Save the data in some state if need, or simply let the user lose the data.
– Neto Marin