We Keep Coding

How to properly close login page?

For example, first activity of app is MainActiviy which is basically 2 text fields (login and password) with a button. Pressing a button tells the database these text fields' data so it can tell the program if the user is in database and password is correct.
What I'm used to is to create a bool flag field saved in SharedPreference so the program knows i already logged in my app recently so it can open my second activity, but it seems like wrong and weird solution.
So, how do I properly login into my app in theory?

Mikkel,
Your approach with storing data using shared preferences is perfect but I have some suggestions which can make this solution better and robust.
First of all, you should check the sharePreference value inside a splash screen. Which checks for the login flag and launch the LoginActivity if a user is not logged in and launch the HomeActivity if a user is logged in.
Second, I would suggest using Androidx DataStore, which is a better version of shared preference and it can be asynchronous API so you can use it safely on the UI thread.
Don't forget to close your main activity after user login using the below code.
Intent intent = new Intent(this,MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();
If you need an example to handle this stuff better here is the github-sample which can be very helpful.

This is wrong:
Intent intent = new Intent(this,MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
finish();
startActivity(intent);
You should use "startActivity" before "finish()"
Correctly:
Intent intent = new Intent(this,MainActivity.class);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();

Settings.ACTION_SOUND_SETTINGS is not going back to app

I am trying to open Sound settings from my app
startActivity(new Intent(Settings.ACTION_SOUND_SETTINGS));
Sound Settings Activity displays without any issue.
Scenarios After Opening Sound settings page
When I press back button on my device, it is going back to my application.
when I click on back arrow button(top left), it is going to Settings Main Screen.
Issue:
I want to go back to my app when click on back icon also.
startActivityForResult(new Intent(Settings.ACTION_SOUND_SETTINGS), 100);
I have also tried this. but no result.
I am testing this on OnePlus 6 (Android 10 (Q))

Create an intent:
Intent intent = new Intent(Settings.ACTION_SOUND_SETTINGS);
Add these lines to your intent:
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.addFlags(Intent.FLAG_ACTIVITY_NO_HISTORY);
intent.addFlags(Intent.FLAG_ACTIVITY_EXCLUDE_FROM_RECENTS);
then call startActivity(intent);

Trying to exit in android. Stack is not correctly cleared

I have been spending lots of hours figuring the reason why top of the stack is not cleared yet.
Well I tried the following:
Intent intent = new Intent(ActionBarActivity.this, MainActivity.class);
intent.addCategory(Intent.CATEGORY_HOME);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
And it turned me to the MainActivity. Then when I try to press back button, the program does not exit, but instead it turns me to the first page of ActionBarActivity.
Let me be more specific:
In MainActivity I call ActionBarActivity. In the ActionBarActivity I have a search bar and I enter a query there and just print the value of the query.
If you think how it will work is a below:
MainActivity -> ActionBarActivity1 -> ActionBarActivity2 -> ActionBarActivity3 -> ..
In that ActionBarActivity I have also an option which brings me back to the MainActivity.
So as I said when I run application with the way above, it will bring me to the MainActivity.
Nice so far, but when I press the back button I expect it to exit, but instead it goes to ActionBarActivity1. I doubt the stack is not properly erased.
What should I do in this case. Thanks

I'm assuming you've seen this post: Android: Clear the back stack and it is not what you want
The FLAG_ACTIVITY_NEW_TASK is creating an new task stack. When you hit "back" that is the only activity in that stack, so Android goes to the previous task - which has the calling activity at the top.
If you remove that flag, then MainActivity is already in the task stack and is brought to the top. And "back" removes it and brings you back to the calling activity. So far, that is the expected Android behavior.
EDIT: Since you commented that you only have 2 activities, then one option is to "finish()" ActionBarActivity after it starts MainActivity like this:
startActivity(intentMainActivity);
finish();
To get the behavior you want with many activities or only in certain situations, you need to use SET_RESULT and finish the activities in the stack when you hit the button to go to the MainActivity. In other words, Android assumes you want to keep activities even when new ones start. But in this case you don't, so you have to tell the activity to destroy itself.
i.e. call setResult(DONE) and then use startActivityForResult and check for your "DONE" flag in the onActivityResult method.
then this:
MainActivity -> ActionBarActivity1 -> ActionBarActivity2 -> ActionBarActivity3
-> MainActivity
becomes:
MainActivity -> ActionBarActivity1 -> ActionBarActivity2 -> ActionBarActivity3
-> call "Done"
Destroy ActionBarActivity3
Destroy ActionBarActivity2
Destroy ActionBarActivity1
MainActivity remains
For example, in ActionBarActivity2:
startActivityForResult(intentActionBarActivity3, ActionBarActivity2_ID);
Then in ActionBarActivity3:
public void exitButton(View view) {
setResult(MY_DONE_FLAG);
finish();
}
And back in ActionBarActivity2:
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == ActionBarActivity2_ID && resultCode == MY_DONE_FLAG) {
setResult(MY_DONE_FLAG, data);
finish();
}
}
And so on with all activities that you want to "close" when that button is pressed.

try
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
finish();
insetead of
intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
and you should also use it with every intent which leads you to ActionBarActivity.
i mean if you are going back to ActionBarActivity form ActionBarActivity1 then you use it with intent.
then create intent for MainActivity in your so called ActionBarActivity.
Intent intent = new Intent(ActionBarActivity.this, MainActivity.class);
intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(intent);
finish();
Good luck !!!

Android activity stack control. Can't figure out how to remove history

I have following 2 activities(plus many more not important for this question):
<activity android:name=".activities.HomeActivity" android:excludeFromRecents="true" />
<activity android:name=".activities.AdHocActivity" android:noHistory="true"/>
HomeActivity is a first one and only one wich I keep history for. User can go differnt places from Home and click Back to come back to main HomeActivity.
I also have service running on alarm and checking for some specific things. When specific criteria met I'm displaying my AdHocActivity
Intent i = new Intent(context, AdHocActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
i.putExtra(BlockingActivity.INTENT_BLOCKED_PACKAGE_NAME, packageName);
context.startActivity(i);
FLAG_ACTIVITY_NEW_TASK was necessary to show Activity from BroadcastReceiver
Now, this AdHoc activity displays some message to user and has a button to take user back to HomeActivity
private void sendToMainApplication()
{
Intent i = new Intent(this, HomeActivity.class);
startActivity(i);
finish();
}
All this work, but I get second instance of HomeActivity in a stack. So now when user taps "Back" - my Home activity flashes and comes back (previous copy).
I want only one copy to stay on top. I want it to be like anchor one. If it doesn't exist - I want new one to be opened.

The trick to prevent HomeActivity from being doubled was to call it like this:
private void sendToMainApplication()
{
Intent i = new Intent(this, HomeActivity.class);
i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();
}

How do I create an android shortcut to an activity?

OK,I'm new at this forum, so don't blame me for putting this in the wrong tags,not putting something in,eg.
I want to learn how to create a shortcut(I did that by Googling) and link it to an activity (In this case, com.android.mms.ui.ComposeMessageActivity)
I tried doing it, but it only showed me a toast saying "Application not installed" and I'm pretty sure it is.
It would be better if you can display a "complete action with another application" dialog.

If I assumed your question correctly, you mean a button or something within an activity that leads to another activity, that being -- "com.android.mms.ui.ComposeMessageActivity"
if your activity that you want to link to is in another application-- then
Intent intent = new Intent();
intent.setComponent(new ComponentName("com.mine", "com.android.mms.ui.ComposeMessageActivity"));
startActivity(intent);
if it is within the same application, then
Intent intent = new Intent(this, ComposeMessageActivity.class);
startActivity(intent);
//optional add this to your manifest to finish the current loading activity so
//as to not keep it in the activity stack
//<activity android:name="yourActivity" android:noHistory="true" ... />
EDIT If you mean a shortcut on a homescreen, then I would create a tiny application that only has one activity which uses the above method to link to a different application. Then I would drag that application to the home screen, and boom. If there's a better way, then please feel free to correct me