How to return values of list from another activity in Android studio?

Question

I'm new to Android Studio and try to develop my first application.

I have 3 activities MainActivity, DashboardActivity, and SplashActivity.

DashboardActivity -

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_dashboard);

        Hooks();
        allQuestionsList=listS;
        Collections.shuffle(allQuestionsList);
        modelClass = listS.get(index);

        setAllData();
  }

SplashActivity-

public class SplashActivity extends AppCompatActivity {
public static ArrayList<ModelClass> listS;

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

    listS = new ArrayList<>();
    listS.add(new ModelClass("here is the question", "a", "b", "c", "d", "answer"));
    listS.add(new ModelClass("Under-inflated tires increase fuel consumption. A single tire under-inflated by 56 kpa (8 psi) can increase fuel consumption by?", "25 per cent", "15 per cent", "Seven per cent", "Four per cent", "Four per cent"));
    listS.add(new ModelClass("You are not allowed to park a vehicle within _____________ of a pedestrian corridor", "9 metres", "3 metres", "30 metres", "15 metres", "15 metres"));
    listS.add(new ModelClass("What class licence permits the holder to operate a motorcycle?", "Class 4", "Class 1", "Class 6", "Class 5", "Class 6"));
    listS.add(new ModelClass("Seatbelts must be worn by all drivers and passengers:", "Only when driving in the city", "Only when carrying passengers", "All the time unless exempted by law", "Only when driving on the highway", "All the time unless exempted by law"));

    new Handler().postDelayed(new Runnable() {
        @Override
        public void run() {
            Intent intent = new Intent(SplashActivity.this, DashboardActivity.class);
            startActivity(intent);
        }
    }, 1500);
}

I try to use the list that is created above but the list always remains empty. I also tried to use getter but without success. After debugging I realized that the splash activity was not running at all

This is my AndroidManifest-

<application
    android:allowBackup="true"
    android:dataExtractionRules="@xml/data_extraction_rules"
    android:fullBackupContent="@xml/backup_rules"
    android:icon="@drawable/mainscreenlogo"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/Theme.QuizTheoryApplication"
    tools:targetApi="31">

    <activity
        android:name=".example.QuizTheoryApplication.MainActivity"
        android:exported="true">
        <intent-filter>
            <action android:name="android.intent.action.MAIN"/>
            <category android:name="android.intent.category.LAUNCHER"/>
        </intent-filter>
    </activity>

    <activity
        android:name=".example.QuizTheoryApplication.DashboardActivity"
        android:label="Preferences"
        android:exported="true">
        <intent-filter>
            <action android:name="com.iphonik.chameleon.AppPreferenceActivity" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>

    <activity
        android:name=".example.QuizTheoryApplication.SplashActivity"
        android:label="Preferences"
        android:exported="true">
        <intent-filter>
            <action android:name="com.iphonik.chameleon.AppPreferenceActivity" />
            <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </activity>

</application>

The problem is that my Splash Activity doesn't run and of course, the list is always empty. I've tried to add in Dashboard activity but without success -

new Handler().postDelayed(new Runnable() 
{ @Override public void run() 
{ Intent intent = new Intent(DashboardActivity.this, SplashActivity.class); startActivity(intent); } }, 1500);

Answer 1

I solved my problem by implementing of a singleton pattern in SplashActivity:

private static SplashActivity instance;

public static SplashActivity getInstance() {
    if (instance== null) {
        synchronized(SplashActivity.class) {
            if (instance == null)
                instance = new SplashActivity();
        }
    }
    // Return the instance
    return instance;
}