InnerClassReferenceLeakActivity.java

public class InnerClassReferenceLeakActivity extends AppCompatActivity {

  /* 
   * Mistake Number 1: 
   * Never create a static variable of an inner class
   * Fix I:
   * private LeakyClass leakyClass;
   */
  private static LeakyClass leakyClass;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_first);
        
        new LeakyClass(this).redirectToSecondScreen();

        /*
         * Inner class is defined here
         * */
         leakyClass = new LeakyClass(this);
         leakyClass.redirectToSecondScreen();
    }
    
  /* 
   * Mistake Number 2: 
   * 1. Never create a inner variable of an inner class
   * 2. Never pass an instance of the activity to the inner class
   */       
    private class LeakyClass {
        
        private Activity activity;
        public LeakyClass(Activity activity) {
            this.activity = activity;
        }
        
        public void redirectToSecondScreen() {
            this.activity.startActivity(new Intent(activity, SecondActivity.class));
        }
    }
}