Solution 1 :
You can make SoundPageChangeListener inner class of your activity, so the Listener can access to the Activity selectedToe variable.
Having an inner class will allow this class SoundPageChangeListener to have visibility and access to your activity selectedToe variable.
The pointer is not kept in your scenario as you are creating a new class instance. Your are assigning currentSound not re-pointing to the memory address.
Then in onPageSelected assign selectedToe with sound
class YourActivity {
...
Sound selectedToe = currentSound // set the default sound if any
// Inside the activity, declare your listener
public class SoundPageChangeListener implements ViewPager.OnPageChangeListener {
private ArrayList<Sound> sounds;
// only the sound list is required here
public SoundPageChangeListener(ArrayList<Sound> sounds) {
this.sounds = sounds;
}
@Override
public void onPageSelected(int position) {
Sound sound = sounds.get(position);
YourActivity.this.selectedToe = sound
}
}
}
Problem :
My Activity has the value Sound selectedToe. I want my soundPageChangeListener to be able to update the selectedToe of the activity, so I pass selectedToe like this:
SoundPageChangeListener soundPageChangeListener = new SoundPageChangeListener(soundsToe, selectedToe);
however, when I change selectedToe inside soundPageChangeListener:
public class SoundPageChangeListener implements ViewPager.OnPageChangeListener {
private ArrayList<Sound> sounds;
Sound currentSound;
public SoundPageChangeListener(ArrayList<Sound> sounds, Sound currentSound) {
this.sounds = sounds;
this.currentSound = currentSound;
}
@Override
public void onPageSelected(int position) {
Sound sound = sounds.get(position);
currentSound = sound;
}
the selectedToe on the activity still null.
Aren’t all java values pointers? If I change something inside the listener, shouldn’t it change outside?
