On Drag Listener multiple IF statements

问题:

I'm making a Letter Drag n Drop game (kinda like Guess the Brand) where you have an image and you have to drag the letters into layouts to form the correct answer.

At the top, I have Four layouts (layoutAnsw A to D), and in the bottom I have Four buttons (btnTop A to D) I have the OnTouchListener and OnDragListener working fine, except one single thing.

What happens when I have more than one similar character (letter)? For example in this image:

As you can see, I have to "A" letters that need to be dragged, and I want to do it regardless of which one you put first. In my code I managed to get something like this:

"If the First A is in the First space, then Second A goes to Second Space"

I'm trying to code the other way around including that previous statement. My code so far let's you put any "A" in any space, including 2 letters in the same space. Pretty useless.

My code so far

public class OneQuestionA extends Fragment implements OnTouchListener,
    OnDragListener {

protected static final String LOGCAT = null;
int numDragged = 0;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    View rootView = inflater.inflate(R.layout.questions_fragment5,
            container, false);

    btnTopA.setOnTouchListener(this); // Letter A
    btnTopB.setOnTouchListener(this); // Second Letter A
    btnTopC.setOnTouchListener(this); 
    btnTopD.setOnTouchListener(this);

    rootView.findViewById(R.id.layoutAnswA).setOnDragListener(this); // Layout 1
    rootView.findViewById(R.id.layoutAnswB).setOnDragListener(this); // Layout 2
    rootView.findViewById(R.id.layoutAnswC).setOnDragListener(this); // Layout 3
    rootView.findViewById(R.id.layoutAnswD).setOnDragListener(this); // Layout 4
return rootView;
}

My onTouch implementation:

 @Override
public boolean onTouch(View view, MotionEvent motionEvent) {
    // TODO Auto-generated method stub
    if (motionEvent.getAction() == MotionEvent.ACTION_DOWN) {
        DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
        view.startDrag(null, shadowBuilder, view, 0);
        view.setVisibility(View.INVISIBLE);
        return true;
    }

    if (motionEvent.getAction() == MotionEvent.ACTION_UP) {
        view.setVisibility(View.VISIBLE);
        return true;
    } else {
        return false;
    }
}

My onDrag implementation:

@Override
public boolean onDrag(View v, DragEvent e) {

    int action = e.getAction();
    View view = (View) e.getLocalState();

    switch (action) {
    case DragEvent.ACTION_DRAG_STARTED:
        return true;
    case DragEvent.ACTION_DRAG_ENTERED:
        return false;
    case DragEvent.ACTION_DRAG_LOCATION:
        return false;
    case DragEvent.ACTION_DRAG_EXITED:
        return false;
    case DragEvent.ACTION_DROP:


        if (view.getId() == R.id.btnTopA && v.getId() == R.id.layoutAnswA) {
            ViewGroup owner = (ViewGroup) view.getParent();
            owner.removeView(view);
            LinearLayout container = (LinearLayout) v;
            container.addView(view);
            view.setVisibility(View.VISIBLE);
            view.setOnTouchListener(null);
            view.setOnDragListener(null);
            numDragged++;
        } else if (view.getId() == R.id.btnTopB && v.getId() == R.id.layoutAnswB) {
                ViewGroup owner = (ViewGroup) view.getParent();
            owner.removeView(view);
            LinearLayout container = (LinearLayout) v;
            container.addView(view);
            view.setVisibility(View.VISIBLE);
            view.setOnTouchListener(null);
            view.setOnDragListener(null);
            numDragged++;
            }
        } 





        if (numDragged >= 4) {
            numDragged = 0;

            Toast.makeText(getActivity(),
                    "All buttons in the Right place", Toast.LENGTH_SHORT)
                    .show();


        }

    case DragEvent.ACTION_DRAG_ENDED:
        if (dropEventNotHandled(e)) {
            view.setVisibility(View.VISIBLE);
        }
    }
    return false;
}

private boolean dropEventNotHandled(DragEvent e) {
    // TODO Auto-generated method stub
    return !e.getResult();
}

回答1:

After a lot of reading, I came across the incredibly simple line:

getChildCount() 

Use that as a condition, anytime there's already another view in place, it will just return false

int i = container.getChildCount();
if (i < 1) {
// Do Something
} else if (i == 1) {
return false;
}