How to Handle Null Object Reference Error with Shared Preferences in Android

What should I do if I encounter a Null Object Reference error while working with Shared Preferences in Android?

// Example of accessing SharedPreferences safely in Android
SharedPreferences sharedPreferences = getSharedPreferences("MyPrefs", Context.MODE_PRIVATE);
if(sharedPreferences != null) {
    String value = sharedPreferences.getString("myKey", null);
} else {
    // Handle null case here
}

A Null Object Reference error in Android typically indicates that you are trying to access an object that hasn’t been properly initialized. When working with Shared Preferences, this can occur if you attempt to retrieve data before the SharedPreferences instance is created or if the context you use is null.

// Safe way to access SharedPreferences
SharedPreferences preferences = context.getSharedPreferences("MyPrefs", Context.MODE_PRIVATE);
if (preferences != null) {
    String data = preferences.getString("key", "default");
} else {
    Log.e("SharedPreferences", "Preferences object is null.");
}

Causes

• Using a null context to access SharedPreferences.
• Trying to read SharedPreferences before it has been initialized.
• Improperly handling the activity lifecycle causing references to become null.

Solutions

• Always check that the Context is not null before accessing Shared Preferences.
• Use `getApplicationContext()` when the current Activity Context might be null.
• Ensure that SharedPreferences is accessed after the Activity has been created.

Mistake: Accessing SharedPreferences with a null context.

Solution: Always use a valid context, preferably `getApplicationContext()` in non-UI components.

Mistake: Not checking if SharedPreferences is initialized before usage.

Solution: Check if the SharedPreferences object is not null.

Mistake: Not considering the lifecycle of the Activity or Fragment when accessing SharedPreferences.

Solution: Use SharedPreferences in the lifecycle methods appropriately, avoiding access on onCreate or before context is available.