Android: Go Back to Previous Activity

Android: Go back to previous activity

Android activities are stored in the activity stack. Going back to a previous activity could mean two things.

1. You opened the new activity from another activity with startActivityForResult. In that case you can just call the finishActivity() function from your code and it'll take you back to the previous activity.

2. Keep track of the activity stack. Whenever you start a new activity with an intent you can specify an intent flag like FLAG_ACTIVITY_REORDER_TO_FRONT or FLAG_ACTIVITY_PREVIOUS_IS_TOP. You can use this to shuffle between the activities in your application. Haven't used them much though. Have a look at the flags here: http://developer.android.com/reference/android/content/Intent.html

As mentioned in the comments, if the activity is opened with startActivity() then one can close it with finish().
If you wish to use the Up button you can catch that in onOptionsSelected(MenuItem item) method with checking the item ID against android.R.id.home unlike R.id.home as mentioned in the comments.

Navigating back to previous Activity

1) when navigation from activity A to B, the android system does not destroy activity A, but takes it to the back stack and adds B to the foreground. thats why when you press the back button or call onBackPressed() from the java code activity B is destroyed and A is set to the foreground. here is an example from the docs : Understand Tasks and Back stack

2) when using an intent/navigateUpFromSameTask activity A is recreated and set to the foreground and B is set to the background, it's like adding another activity A to the stack so it will be A,B,A but if you press the back btn then you will be back to B and then A.

if you want to keep the scroll position and other data in activity A you call the onBackPressed in B or use the onSaveInstanceState to save the data and use it in the onCreate .

here is an example of saved instance:

@Override
public void onSaveInstanceState(Bundle savedInstanceState) {
    super.onSaveInstanceState(savedInstanceState);
    savedInstanceState.putString("VariableName", variableData);
    savedInstanceState.putString("VariableName", variableData);
    savedInstanceState.putString("VariableName", variableData);
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.penguin_main);

    if(savedInstanceState!=null){
    bookData = (String) savedInstanceState.getSerializable("VariableName");
    bookData =  (String) savedInstanceState.getSerializable("VariableName");
    bookData =  (String) savedInstanceState.getSerializable("VariableName");
    }
}

Go back to a specific activity without starting it again

Using just a clear top flag causes the target activity to get destroyed first and then recreated. To avoid this, use two flags:

intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);

this will cause the activity to not get finished thus your API call wont happen again. The intent you use here to start the activity A will be delivered to onNewIntent() method in activity A in this case if you need it.

This is all assuming that you have not specified any launch mode in your activity manifest declaration of are using "multiple" launch mode.

As per the docs:

If it has declared its launch mode to be "multiple" (the default) and you have not set FLAG_ACTIVITY_SINGLE_TOP in the same intent, then it will be finished and re-created; for all other launch modes or if FLAG_ACTIVITY_SINGLE_TOP is set then this Intent will be delivered to the current instance's onNewIntent().

How to close activity and go back to previous activity in android

I think you are calling finish() method in MainActivity before starting SettingsActivity.

The scenario which you have described will occur in following two ways:

EITHER

You have set android:noHistory = "true" for MainActivity inside AndroidManifest.xml which causes MainActivity to finish automatically on pressing the back key.

OR

Before switching to your 'SettingsActivity', you have called finish() in your MainActivity, which kills it. When you press back button,since no other activity is preset in stack to pop, it goes back to main screen.

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