Develop Reference

Disabling back button on multiple activities (Android)

I have seen this question:
Disable back button in android
(Please do not mark as duplicate for this.)
My query is this:
I have twenty activities in a row. I want to disable the back button, so that the user can never come back to the activity he once crosses. Currently, how I do this is override onBackPressed() and remove the super.onBackPressed() call. This works fine.
I now need to add forty more activities, and it should have the same effect. Is there a method where I can just disable the back button for the entire application without having to code it up in each Activity?

Create BaseActivity and extend every your Activity with this BaseActivity, and add onBackPressed() logic in BaseActivity.
Ex:
public class BaseActivity extends AppCompatActivity {
// Add your onBackPressed() logic here
}
Your activity,
public class MyActivityA extends BaseActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my_activity);
}
}

U can achieve this by finishing the pervious activity while going to next activity.

Using activities from library

I'm creating my first library to use in some future projects, on it I'm creating some Activities that are the same on every project.
Right now I'm working with a test project and on my library I have this LoginActivity. It has it's own layout and works fine.
How can I make my test app LoginActivity be the one from the library? At the moment I'm extending my LoginActivity from the library into my activity on the project. Is this the right way of doing it considering that all the code logic happens on the Library activity?
Library LoginActivity
public class LoginActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
// Some useless code...
}
}
Project Login Activity
public class MainActivity extends LoginActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Nothing happens in this class... really...
}
}

Make sure that Activity that is inside of the library project is declared inside of the library's manifest file. Then start the activity how you normally would start any other activity. If you want the activity to be the first activity when the app launches (launcher activity), you need to declare it explicitly inside of your manifest and add an intent-filter tag element as a child, that indicates it should be the launcher activity. View this post.. Another way to roughly achieve the same effect would be to create a blank activity that is declared in the app manifest file as the launcher activity and inside of the onCreate method launch the library activity. Make sure you clear any and all activity transitions so that the switch to the library activity is seamless. The benefit to this approach is that you can perform a check before launching the library activity.
Ex. checking if the login activity needs to be displayed or if the screen can be by-passed and the app can be entered immediately.

Add login activity into AndroidManifest.xml in library or application.
<application>
<activity
android:name="com.mypackage.LoginActivity" />
</application>

Enable taking screenshot of a App after disabled using FLAG_SECURE

Using the code below I prevent users taking screenshots of my app. I want to implement "enable screenshot button". Is it possible? Which concept should I use?
public class FlagSecureTestActivity extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
getWindow().setFlags(LayoutParams.FLAG_SECURE,
LayoutParams.FLAG_SECURE);
setContentView(R.layout.main);
}
}

You could restart the activity and this time not set the SECURE flag.
In my app, I have a switch in settings to enable or disable the secure flag. Then I simply do not set it if the settings specifies that I am allowed to take screenshots.

Android: Two actvities as launchers

I'm developing locker application. I created service and receiver to hide default android locker. But for few days I have problem with settings activity. I'm looking for a solution, how to make two activites as launchers. I want to make something like that:
Locker activity is only launched when phone is locked. And Settings activity only when I press app icon in menu. Is it possible to programme?
Thanks for help.

You can try to launch the same activity but changing the content view (into onCreate) for each situation. Something like:
if (isLocked()) {
setContentView(R.layout.locker_activity);
} else {
setContentView(R.layout.settings_activity);
}

You can use just one activity as launcher and use Fragments to load what you want. Something like this:
public class LauncherActivity extends FragmentActivity {
super.onCreate(savedInstanceState);
Fragment fragment;
if (isLocked()) {
fragment = new LockerFragment();
}
else {
fragment = new SettingsFragmentFragment();
}
getFragmentManager().beginTransaction().add(R.id.container_id,fragment).commit();
}

Kill and destroy activity

The first screen of my application is a login screen, so I used the method finish () after user have logged. However when i return the application I would like to be already logged. I tried to use onDestroy (), but without success.

It'll be better if you implement your logic otherwise. The first screen in your application can be HomeScreenActivity in which you'll check if the user is logged and start LoginActivity if needed.
public class HomeScreenActivity extends Activity {
/* some declaration */
public void onCreate(Bundle savedInstanceState) {
/* some other stuff */
if (!userIsLogged()) {
Intent intent = new Intent(this,LoginActivity.class);
startActivity(intent);
}
}
}

You have to use SharedPreferences.
See Data Storage on Android Developer

You might want to have a look at the Activity Life Cycle... Furthermore SharedPreferences can be used to save username/login details but im of the understanding that they can be accessed by any application, so be careful what you put there.