Can an application field become null?

Issue

In my Android app I have set a custom Application-derived class. In it I have a member field to store some arbitrary object in.

So I have:

public class MyApp extends Application {

public static MyApp mInstance;
public Object mData;

@Override
public void onCreate() {
   mInstance = this;
}

public void setData(Object data) {
    mData = data;
}

public Object getData() { return mData; } 

}

Now in one Activity I'm doing

public doSetData() {

     someMyData = ....
     MyApp.mInstance.setData(someMyData);

}

In another Activity I'm doing

@Override
public void onCreate(Bundle) {

     Object myDataRetrieved = MyApp.mInstance.getData();

}

I can see that sometimes myDataRetrieved is null. However, I believe I have never passed null in MyApp.setData(). Of course, I can be wrong.

Yet, can there be such circumstances under which MyApp.mData becomes null by itself?

Solution

Yet, can there be such circumstances under which MyApp.mData becomes null by itself?

Sure. It will happen every time Android terminates the process, which will happen when your app is not in the foreground, Android needs RAM, and your app is next in line to be terminated.

Answered By - CommonsWare