Android Data Loading Issue: Complete Guide

Data saved locally in your Android app but not displaying after restart typically stems from improper data loading logic rather than saving issues. The most common causes include missing data restoration in your activity’s lifecycle methods, incorrect usage of onSaveInstanceState (which only works for configuration changes, not app restarts), or failing to properly read SharedPreferences/database data when the app initializes. To fix this, ensure you’re implementing proper data loading mechanisms in onCreate(), using SharedPreferences with commit() or apply() methods, and considering ViewModel with SavedStateHandle for UI state persistence.

Contents

• Common Causes of Data Loading Issues
• Proper Data Saving and Loading Methods
• SharedPreferences Implementation Best Practices
• Database Data Persistence Solutions
• Lifecycle Management for Data Restoration
• Debugging and Troubleshooting Steps

Common Causes of Data Loading Issues

The primary reason your saved data isn’t displaying after app restart is likely related to how you’re handling data restoration in the activity lifecycle. Based on the research findings, several common patterns emerge:

Missing Data Restoration Logic
Many developers save data correctly but forget to implement the corresponding loading logic. When your app restarts, onCreate() is called, but if you haven’t included code to read from SharedPreferences, database, or files, the UI will remain empty.

// INCORRECT - no data loading
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    // Missing: loadSavedData();
}

// CORRECT - includes data loading
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    loadSavedData(); // Add this
}

Misunderstanding onSaveInstanceState
The onSaveInstanceState() and onRestoreInstanceState() methods are only triggered during configuration changes (like screen rotation), not when the app is completely restarted and reopened. As one Stack Overflow answer explains: “onSaveInstance and onRestoreInstance method are triggered only, when a destruction because of orientation change happens, hence you can not use this mechanism with that purpose.”

SharedPreferences Not Properly Saved
If you’re using SharedPreferences, the issue might be that you’re not calling commit() or apply() after saving data. The commit() method writes data to persistent storage immediately, while apply() does it in the background. Without this call, your data may not actually be saved.

Proper Data Saving and Loading Methods

To ensure your data persists and displays correctly after app restart, implement these proven methods:

SharedPreferences Implementation

// Saving data
public void saveUserData(String username, int score) {
    SharedPreferences prefs = getSharedPreferences("user_data", Context.MODE_PRIVATE);
    SharedPreferences.Editor editor = prefs.edit();
    editor.putString("username", username);
    editor.putInt("score", score);
    editor.commit(); // or editor.apply() for async saving
}

// Loading data
private void loadUserData() {
    SharedPreferences prefs = getSharedPreferences("user_data", Context.MODE_PRIVATE);
    String username = prefs.getString("username", "default_user");
    int score = prefs.getInt("score", 0);
    
    // Update UI with loaded data
    textViewUsername.setText(username);
    textViewScore.setText(String.valueOf(score));
}

Using ViewModel with SavedStateHandle

For modern Android development, consider using ViewModel with SavedStateHandle:

public class MyViewModel extends ViewModel {
    private SavedStateHandle savedStateHandle;
    
    public MyViewModel(@NonNull SavedStateHandle savedStateHandle) {
        this.savedStateHandle = savedStateHandle;
    }
    
    public void saveData(String key, String value) {
        savedStateHandle.set(key, value);
    }
    
    public String loadData(String key, String defaultValue) {
        return savedStateHandle.get(key, defaultValue);
    }
}

As the Android Developers documentation states: “To reload data after a system-initiated process death in a ViewModel, use the SavedStateHandle API.”

SharedPreferences Implementation Best Practices

Based on the research findings, here are the key practices to follow for reliable SharedPreferences usage:

Correct Saving Methods

Always use commit() or apply()
The most common mistake is calling edit().putString() without finalizing the save operation:

// WRONG - data won't persist
SharedPreferences.Editor editor = prefs.edit();
editor.putString("key", "value");
// Missing: editor.commit() or editor.apply()

// CORRECT
SharedPreferences.Editor editor = prefs.edit();
editor.putString("key", "value");
editor.commit(); // Synchronous - blocks until written
// OR
editor.apply(); // Asynchronous - writes in background

Choose the Right Mode
Use Context.MODE_PRIVATE for most cases to ensure your data is only accessible by your app:

SharedPreferences prefs = getSharedPreferences("app_prefs", Context.MODE_PRIVATE);

Loading Data Properly

// In onCreate() of your Activity
SharedPreferences prefs = getSharedPreferences("app_prefs", Context.MODE_PRIVATE);
String savedValue = prefs.getString("key", "default_value");

// Update UI components
textView.setText(savedValue);

Database Data Persistence Solutions

If you’re using SQLite databases, the issue might be related to database access patterns:

Room Database Implementation

@Entity
public class User {
    @PrimaryKey
    public int uid;
    
    @ColumnInfo(name = "name")
    public String name;
    
    @ColumnInfo(name = "score")
    public int score;
}

@Dao
public interface UserDao {
    @Query("SELECT * FROM user WHERE uid = :uid")
    User getUser(int uid);
    
    @Insert
    void insert(User user);
}

// Usage in Activity
private void loadUserData() {
    new Thread(() -> {
        User user = userDao.getUser(1);
        runOnUiThread(() -> {
            textViewName.setText(user.name);
            textViewScore.setText(String.valueOf(user.score));
        });
    }).start();
}

Lifecycle Management for Data Restoration

Proper Activity Lifecycle Usage

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    // Load saved data
    loadSavedData();
}

@Override
protected void onResume() {
    super.onResume();
    // Additional data loading if needed
}

private void loadSavedData() {
    // Your data loading implementation
    SharedPreferences prefs = getSharedPreferences("app_data", Context.MODE_PRIVATE);
    String data = prefs.getString("saved_data", "");
    
    if (!data.isEmpty()) {
        // Update UI with loaded data
        updateUIWithSavedData(data);
    }
}

Debugging and Troubleshooting Steps

When your data isn’t displaying after restart, follow these debugging steps:

Step 1: Verify Data is Actually Saved

Add logging to confirm data is being saved:

// When saving
SharedPreferences.Editor editor = prefs.edit();
editor.putString("test_key", "test_value");
editor.commit();
Log.d("DataSave", "Data saved: " + prefs.getString("test_key", "NOT_FOUND"));

Step 2: Check File Permissions

Sometimes “Clear User Data” settings can cause issues. As one Stack Overflow answer notes: “the ‘Clear User Data’ flag was set under ‘Deployment’ in the project properties.”

Step 3: Test Different Storage Methods

If SharedPreferences isn’t working, try alternative approaches:

1. Internal Storage:

// Save
FileOutputStream fos = openFileOutput("data.txt", Context.MODE_PRIVATE);
fos.write("your data".getBytes());
fos.close();

// Load
FileInputStream fis = openFileInput("data.txt");
StringBuilder data = new StringBuilder();
byte[] buffer = new byte[1024];
int bytesRead;
while ((bytesRead = fis.read(buffer)) != -1) {
    data.append(new String(buffer, 0, bytesRead));
}
fis.close();

2. Database: Use Room for complex data structures

Step 4: Handle Force Closes

Device restarts can clear SharedPreferences. Consider using a database for critical data that must survive reboots, as mentioned in the research: “This is due to SharedPreferences being killed while reboot.”

Sources

1. Stack Overflow - Save the data and using it after restarting the app Android
2. Android Developers - Save UI states | App architecture
3. Stack Overflow - Saved data lost when I restart the application(android)
4. Stack Overflow - settings from PreferenceActivity not saved after app restart
5. Stack Overflow - Android internal files seems to disappear after I restart my application
6. Stack Overflow - SharedPreferences not persistent after app restart
7. CodePath Android Cliffnotes - Persisting Data to the Device
8. Medium - Data Persistence: Making Your Treasures Last in Android Apps
9. Android Developers - Use saved Preference values

Conclusion

To resolve your Android app’s data loading issue after restart, focus on these key areas:

1. Implement proper data loading in your Activity’s onCreate() method, ensuring you read from SharedPreferences, databases, or files before updating the UI.

2. Use correct saving methods - always call commit() or apply() after modifying SharedPreferences to ensure data persists properly.

3. Consider modern approaches like ViewModel with SavedStateHandle for better state management across configuration changes and process deaths.

4. Test different persistence methods - SharedPreferences work well for simple key-value pairs, but consider Room database for complex data that needs to survive device reboots.

5. Debug systematically - verify data is actually being saved, check for permission issues, and test alternative storage methods if needed.

By following these practices, you’ll ensure your app consistently loads and displays previously saved data when reopened, providing a smooth user experience across app sessions.