public class MyTest { 
    static MyTest instance = null; 
    Context appctx = null;
    public static MyTest Instance() {
        if (null == instance) {
            instance = new MyTest();
        }
        return instance;
    }
    // call from Application onCreate  MyTest.Instance().onAppCreate(this);
    public void onAppCreate(Context context) {
        appctx = context;
    }
    // call from Activity onCreate MyTest.Instance().onActivityCreate(this);
    public void onActivityCreate(Activity act) {
        if (null == appctx) {
            Log.d("error", "null app");
        }
    }
}

Is appctx null because instance is reclaimed by gc or what?

Above is an abbreviated version of a class in my app. appctx would not be null in the onActivityCreate function, but why would appctx be null in some cases