Android static Application.getInstance()

Question

Could you help me with this situation. We are using a static instance of a class that extends Application in android.

public class MyClass extends Application {

    public static MyClass getInstance() {
        if(mInstance == null)
        {
            mInstance = new MyClass();
        }
        return mInstance;
    }

    public MyObject getMyObject() {
        return myObject;   
    }
}

MyObject should be accessible everywhere and we are accessing like . MyClass.getInstance().getMyObject(). It works most of the time. Sometimes in Service method this instance returns null. But when we access this object immediately in the same control within an Activity on UserLeaveHint() or onPause() when we try to print this object the same instance returns with a valid object and not null. Could someone please help us out?

Answer 1

You should instantiate the singleton class with an other way (and not simply create a new object), in OnCreate method which is called when application starts:

public class MyClass extends Application {

    // Singleton instance
    private static MyClass sInstance = null;

    @Override
    public void onCreate() {
        super.onCreate();
        // Setup singleton instance
        sInstance = this;
    }

    // Getter to access Singleton instance
    public static MyClass getInstance() {
        return sInstance ; 
    }
}

And be sure to link this class to application tag in Manifest.xml

...
<application
    android:name="package.MyClass"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme">
...
</application>
....