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.

You can go back to the previous activity by just calling finish() in the activity you are on. Note any code after the finish() call will be run - you can just do a return after calling finish() to fix this.

If you want to return results to activity one then when starting activity two you need:

startActivityForResults(myIntent, MY_REQUEST_CODE);

Inside your called activity you can then get the Intent from the onCreate() parameter or used

getIntent();

To set return a result to activity one then in activity two do

setResult(Activity.RESULT_OK, MyIntentToReturn);

If you have no intent to return then just say

setResult(Activity.RESULT_OK);

If the the activity has bad results you can use Activity.RESULT_CANCELED (this is used by default). Then in activity one you do

onActivityResult(int requestCode, int resultCode, Intent data) {
    // Handle the logic for the requestCode, resultCode and data returned...
}

To finish activity two use the same methods with finish() as described above with your results already set.

if you use fragment u should use

getActivity().onBackPressed();

if you use single activity u can use

finish();