What are intent-filters in Android

Question

I intended to start new activity "B" in my Android app from the first activity "A." Both of them have classes that I've created. However, I receive the runtime error: programme has terminated suddenly, try again when I use the following code to start B. This is my code:

Intent myIntent = new Intent(this, AddNewActivity.class);
startActivity(myIntent); 

The application only functioned when I added a new entry for activity B to AndroidManifest.xml/manifest/application/activity/intent-filers.

I have two inquiries.

1. How does Android decide which activity to start first when there are many entries for one activity in AndroidManifest.xml?
2. I was unable to comprehend intent-filters. Could someone kindly explain.

This is a portion of my AndroidManifest.xml.

<application android:icon="@drawable/icon" android:label="@string/app_name">
    <activity android:name=".ListAllActivity"
              android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".AddNewActivity" android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

Answer 1

Just for the record. This is how I've signed a user out of a HomeActivity that isn't LoginActivity. The signOut() function in the LoginActivity must be called either from the onCreate() or onStart() method, and the LoginActivity must be started from another Activity (in my example, HomeActivity) when you want the user to sign out.