java - 调用了错误的 onDrag 类

Question

我正在创建一个应用程序，用户可以在其中购买建筑物，这些建筑物是也实现拖放 API 的图像按钮。目前我遇到一个问题，假设我已经购买了 2 栋建筑:colonyHutOne 和 colonyHutTwo。它们都有自己的 onDrag 类和 onDragListeners 分别设置。当任一建筑物被拖动到某处时，第二个建筑物的 onDrag 类将被调用(因为它是最后一个被购买并插入到 View 中的建筑物)。我不知道要阻止这一切。应该是，当第一个建筑物被移动时，它会调用自己的 onDrag ，以便为正确的建筑物保存建筑物的坐标，但由于它只是调用最近创建的建筑物的 onDrag 类，因此不会保存坐标正确。

这是两个图像按钮的 onDragListeners 的代码:

对于 colonyHutOne 建筑:

findViewById(R.id.topHalf).setOnDragListener(new ColonyHutOneDrag(getApplicationContext()));
findViewById(R.id.bottomHalf).setOnDragListener(new ColonyHutOneDrag(getApplicationContext()));
FrameLayout.LayoutParams  param1 = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT);
newColonyHutFrame.addView(newColonyHutOne, param1);

对于 colonyHutTwo 建筑:

findViewById(R.id.topHalf).setOnDragListener(new ColonyHutTwoDrag(getApplicationContext()));
findViewById(R.id.bottomHalf).setOnDragListener(new ColonyHutTwoDrag(getApplicationContext()));
FrameLayout.LayoutParams  param1 = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT);
newColonyHutFrame.addView(newColonyHutTwo, param1);

这是 onDrag 类的代码:

对于 colonyHutOne 建筑:

public class ColonyHutOneDrag implements OnDragListener
{
SharedPreferences prefs;
Context passedContext;
Database data;

public ColonyHutOneDrag(Context applicationContext) 
{
    passedContext = applicationContext;
}//end constructor

@Override
public boolean onDrag(View v, DragEvent event) 
{
    float x = 0, y = 0;
    switch(event.getAction())
    {
        case DragEvent.ACTION_DRAG_STARTED:
            //drag has started
            break;

        case DragEvent.ACTION_DRAG_ENTERED:
            //being dragged
            break;

        case DragEvent.ACTION_DRAG_EXITED:
            //stop drag
            break;

        case DragEvent.ACTION_DRAG_LOCATION:
            //find drag location
            break;

        case DragEvent.ACTION_DROP:
            if (v == v.findViewById(R.id.bottomHalf))
            {
                //find position where dropped
                x = event.getX();
                y = event.getY();

                //save the coordinates that the building was dropped at
                data = new Database(passedContext);
                data.open();
                data.colonyHutOneXEntry(x);
                data.colonyHutOneYEntry(y);
                data.close();
                Toast.makeText(passedContext, "Going in1 -> x: " + x + " y: " + y, Toast.LENGTH_SHORT).show();

                //use this to fix building loadup glitch
                View view = (View) event.getLocalState();
                ViewGroup group = (ViewGroup) view.getParent();
                group.removeView(view);
                FrameLayout contain = (FrameLayout) v;
                contain.addView(view);
                view.setX(x - (view.getWidth()/2));
                view.setY(y - (view.getHeight()/2));
                view.setVisibility(View.VISIBLE);
            }//end if
            else
            {
                View view = (View) event.getLocalState();
                view.setVisibility(View.VISIBLE);
            }//end else
            break;

        default:
            break;
    }//end switch
    return true;
}//end onDrag function
}//end ColonyHutOneDrag class

对于 colonyHutTwo 建筑:

public class ColonyHutTwoDrag implements OnDragListener
{
SharedPreferences prefs;
Context passedContext;
Database data;

public ColonyHutTwoDrag(Context applicationContext) 
{
    passedContext = applicationContext;
}//end constructor

@Override
public boolean onDrag(View v, DragEvent event) 
{
    float x = 0, y = 0;
    switch(event.getAction())
    {
        case DragEvent.ACTION_DRAG_STARTED:
            //drag has started
            break;

        case DragEvent.ACTION_DRAG_ENTERED:
            //being dragged
            break;

        case DragEvent.ACTION_DRAG_EXITED:
            //stop drag
            break;

        case DragEvent.ACTION_DRAG_LOCATION:
            //find drag location
            break;

        case DragEvent.ACTION_DROP:
            if (v == v.findViewById(R.id.bottomHalf))
            {
                //find position where dropped
                x = event.getX();
                y = event.getY();

                //save the coordinates that the building was dropped at
                data = new Database(passedContext);
                data.open();
                data.colonyHutTwoXEntry(x);
                data.colonyHutTwoYEntry(y);
                data.close();
                Toast.makeText(passedContext, "Going in2 -> x: " + x + " y: " + y, Toast.LENGTH_SHORT).show();

                //use this to fix building loadup glitch
                View view = (View) event.getLocalState();
                ViewGroup group = (ViewGroup) view.getParent();
                group.removeView(view);
                FrameLayout contain = (FrameLayout) v;
                contain.addView(view);
                view.setX(x - (view.getWidth()/2));
                view.setY(y - (view.getHeight()/2));
                view.setVisibility(View.VISIBLE);
            }//end if
            else
            {
                View view = (View) event.getLocalState();
                view.setVisibility(View.VISIBLE);
            }//end else
            break;

        default:
            break;
    }//end switch
    return true;
}//end onDrag function
}//end ColonyHutTwoDrag class

这是开始拖动的 onTouchListener:

public class BuildingsClick implements OnTouchListener 
{   
@Override
public boolean onTouch(View v, MotionEvent event) 
{
    ClipData.Item item = new ClipData.Item((CharSequence)v.getTag());

    String[] mimeTypes = { ClipDescription.MIMETYPE_TEXT_PLAIN }; 
    ClipData data = new ClipData(v.getTag().toString(), mimeTypes, item); 
    DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(v); 

    v.startDrag(data, shadowBuilder, v, 0);
    v.setVisibility(View.INVISIBLE);

    return false;   
}//end onTouch function

}//end BuildingsClick class

即使我拖动第一个建筑物，每次都会调用第二个建筑物的 onDrag 对我来说毫无意义。请大家帮忙。

谢谢。

Answer 1

我认为您的问题是您将 findViewById(R.id.topHalf) 的 OnDragListener 设置为 new ColonyHutOneDrag(getApplicationContext()).

然后将同一 View 的 OnDragListener 设置为 new ColonyHutTwoDrag(getApplicationContext())在那之后。第二个调用会覆盖第一个调用，并且来自 ColonyHutOneDrag 的代码永远不会运行，因为它不再是 Activity 监听器。

同样的问题会影响您的 View findViewById(R.id.bottomHalf)。

您要么想要将两个监听器合并为一个，让监听器决定其建筑类型，要么显式设置每个 View 的 OnDragListener。我建议采用前一种方法。

编辑:如果您的自定义类是正在传递的 View 的子类，这将起作用。如果您的类不是 View 的子类化，您可以在其中一个类中使用变量来区分另一个类(就像您比较的字符串而不是 if(v instance of class))。

switch(((View)v.getParent()).getID())
{
case R.id.topHalf:
    if(v instanceof ColonyHutOne)
        topHalfColonyOne();
    else if(v instanceof ColonyHutTwo)
        topHalfColonyTwo();
    break;
case R.id.bottomHalf:
    if(v instanceof ColonyHutOne)
        bottomHalfColonyOne();
    else if(v instanceof ColonyHutTwo)
        bottomHalfColonyTwo();
    break;
}