How do I re-run the activity after checking the GPS usage on the Android GPS settings screen and clicking the Back button?

String gpsEnabled;

Intent intent;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    chkGpsService();
}

private boolean chkGpsService() {

    //Confirmed that GPS is turned on.
    gpsEnabled = android.provider.Settings.Secure.getString(getContentResolver(), Settings.Secure.LOCATION_PROVIDERS_ALLOWED);

    if (!(gpsEnabled.matches(".*gps.*") && gpsEnabled.matches(".*network.*"))) {
        If //gps is not enabled,
        new AlertDialog.Builder(this).setTitle ("GPS Settings").setMessage ("GPS is turned off). \nDo you want to enable GPS?").setPositiveButton("GPS On", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int which) {
                //GPS setup screen displayed
                Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                startActivity(intent);
            }
        }).setNegativeButton("Close", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialogInterface, int i) {

            }
        }).create().show();

    }else if((gpsEnabled.matches(".*gps.*") && gpsEnabled.matches(".*network.*"))) {
        Toast.makeText(getApplicationContext(), "Reading information.", Toast.LENGTH_LONG).show();
        intent = new Intent (this, CurrentLocatinActivity.class); // Execute the int to display the current location screen.
        startActivity(intent);
    }
    return false;
}