Develop Reference

Use back button instead of icon to register user input in Android

(first-timer here, so apologies for protocol errors...)
I have an app where the user can edit an item, then click on an icon to have the edits saved. Now, I would like to have the edits saved when the "back" button is pressed.
I tried using onBackPressed, but that didn't help.
Some gory details... When the icon is clicked, it triggers onOptionsItemSelected, where i have inserted code that loads the user's changes into an intent (can SOMEONE please tell me how the Android people chose to name it "intent"?), and then I have
return true;
The main then gets the intent in onActivityResult and finishes the processing.
onBackPressed fills up the intent, but returns "void", and when the main gets control, the intent it receives is "null".
Anyone know how I can get the back button to get the intent to the main?
Thanks

Closing the background activity which has the same name

I'm trying to develop an app which has two editText fields for entering location. So I made two java files
1.MapsActivity.java(with activity_maps.xml)
2.AutoComplete.java(with autocomplete.xml)
In MapsActivity while clicking the 'from' text field, it will open the AutoComplete activity and after clicking any of the suggestions in it will open a fresh MapsActivity and places the clicked item . Likewise for 'to' text field also.
I am using Intents to pass the clicked values. So at last, five activities are opened when the two text boxes are filled. When I click back button ,it is showing the auto complete activity used the previous time.
Question:
Is any other way to close a particular activity with same name running behind?
Is there any other way to pass values by super.backpressed(); ?
enter image description here

You can try using startActivityForResult() method. That way you can use the result from the second activity in the first and also you wouldn't need to start a new activity. You can read up on it here startActivityForResult

try to clear backstack/clear_top/single_top using the intent.
Just add/set flags in intent.
or
finish activity after startActivity.
or
you can override the onBackPressed method to call the specific activity.

Perform a button click when activity opens

I have an activity which has a button which opens up a custom AlertDialog (in which user can enter some data) when pressed. I now have a requirement to open this activity with the alert dialog open initially.
I know that I can perform a click on the button programmatically by calling button.performClick();. My question is, when should I call this? Is it safe to call it in onCreate()?

Yes , you can call it in onCreate() , if you want to call it only once,
but if want call that again you leave and come back to Activity it will be better to add in onResume().

Yes, you can call it in onCreate(), but if you set the AlertDialog as a login, I think it will be in onStart(). Because when you go to desktop, then if you want to get back, you should login again, right? And you can read the detailed information in this.

How to access KeyChain.choosePrivateKeyAlias activity?

The following method:KeyChain.choosePrivateKeyAlias creates system dialog which allows user to choose a key alias from a list. As one of the arguments it takes Activity context which will be used to spawn this dialog. When selection is made it will call a callback.
In my scenario user doesn't select any alias but presses "Home" button. I would like to intercept this event. How can I do that?
Also I would like to cancel this dialog programatically. In this case I need some way to access this child Activity (please note that choosePrivateKeyAlias doesn't return any "handle" to the new dialog). Is it possible to access child Activity without any references (handle/id/etc.) to it?

There is no way to programatically end that activity because it is a system activity. It's the same as launching the browser on your device or the contact list. The only way to exit it is to press back and it will close that activity and resume yours.

According to my understanding, if you want to dismiss that dialog. Then as far as I know about Android OS. There are lifecycle methods for Activity. So I think
IF YOU CALL "yourDailog.dismiss()" INSIDE YOUR ACTIVITY's "onStop()". SO YOUR PROBLEM WILL BE SOLVED
If you do it in above way, so whenever you press HOME button, It will call onStop method of your activity. At that time, It will dismiss that dialog.

How to dismiss Dialog on backKey Pressed!

Friends i have an application with an Activitiy which brings some data from Content Providers and Display it in the textViews and edittext onto the Screen. but before that it prompts me for the username and password in a dialog. i have done all the getting content Providers Stuff in the positiveButton onClick Listener of the Alert Dialog.
It works fine but problem is that if i dont enter username and just press bakc key button it closses down the Dialog Box and the Back Screen is showed without loading the content providers.
Note: I have put my code of alert dialog in the onCreate Function of that activity.
So can u guide me how should i do it that when i press back key on dialog box it also should not display my activity.
Please Help!

your dialog name here.setCancelable(false);
this is working

I would honestly just do:
mDialog.setCancelable(false); //assuming the field mDialog is your Dialog
Then make sure you have both an Okay and Cancel (Positive and Negative) buttons on your Dialog. This way, the back press will do nothing, and you can use the Cancel button to finish your activity as well if desired.

The Dialog interface provides a setCancelable() method which enables precisely this. You call that with a false value and the user won't be able to press the back button to go back to your activity.

You can use method of each activity is : onBackPressed()
http://developer.android.com/reference/android/app/Activity.html
-This is the method which you can override sub method to execute when user enter back key.