blocks|key|204133|text|查看View的源代码，我看到：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|204134|static+final+int+DRAG_CAN_ACCEPT++++++++++++++=+0x00000001;
int+mPrivateFlags2;

boolean+canAcceptDrag()+{
++++return+(mPrivateFlags2+&+DRAG_CAN_ACCEPT)+!=+0;
}|code-block|syntax|javascript|204135|mPrivateFlags2是包私有的，不会被SDK公开。但是，您应该能够通过执行以下操作在子类中更改它：|204136|try+{
++++Field+mPrivateFlags2+=+this.getClass().getField("mPrivateFlags2");
++++int+currentValue+=+mPrivateFlags2.getInt(this);
++++mPrivateFlags2.setInt(this,+currentValue+%7C+0x00000001);
}+catch+(Exception+e)+{
}|204137|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

Looking at the source for View, I see:

<pre><code>static final int DRAG_CAN_ACCEPT = 0x00000001;
int mPrivateFlags2;

boolean canAcceptDrag() {
 return (mPrivateFlags2 &amp; DRAG_CAN_ACCEPT) != 0;
}
</code></pre>

mPrivateFlags2 is package-private and not exposed by the SDK. However, you should be able to change it in a subclass by doing:

<pre><code>try {
 Field mPrivateFlags2 = this.getClass().getField("mPrivateFlags2");
 int currentValue = mPrivateFlags2.getInt(this);
 mPrivateFlags2.setInt(this, currentValue | 0x00000001);
} catch (Exception e) {
}
</code></pre>

blocks|key|422395|text|在listview中实现拖放的最简单方法是使用这个很棒的库。https://github.com/commonsguy/cwac-touchlist，值得一试。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|422396|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/commonsguy/cwac-touchlist^0|U|18|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@$A|M|B|N|1|O]]|C|$]]|$1|D|3|-4|5|6|7|P|8|@]|9|@]|C|$]]]|E|$F|$5|G|H|I|C|$J|K]]]]

An easiest way to implement drag and drop in listview is you use this great library. 
<a href="https://github.com/commonsguy/cwac-touchlist" rel="nofollow">https://github.com/commonsguy/cwac-touchlist</a>
it's worth trying.

blocks|key|422452|text|我有same+problem。我没有解决这个回收问题，但我发现了一个可能的变通方法，仍然使用拖放框架。这个想法是为了改变视角:不是在列表中的每个View上使用OnDragListener，而是可以直接在ListView上使用它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|422453|然后，在执行拖放操作时，找到手指位于哪个项目的顶部，并在ListView的ListAdapter中编写相关的显示代码。然后，技巧是找到我们在哪个项目视图的顶部，以及在哪里完成了拖放。|422454|为此，我将适配器创建的每个视图的ListView位置设置为id+-使用View.setId()，这样我以后就可以使用ListView.pointToPosition()和ListView.findViewById()的组合找到它。|422455|作为一个拖拽监听器的例子(我提醒你，这是在ListView上应用的)，它可以是这样的：|422456|//+Initalize+your+ListView
private+ListView+_myListView+=+new+ListView(getContext());

//+Start+drag+when+long+click+on+a+ListView+item
_myListView.setOnItemLongClickListener(new+AdapterView.OnItemLongClickListener()+{
++++@Override
++++public+boolean+onItemLongClick(AdapterView<?>+parent,+View+view,+int+position,+long+id)+{
++++++++DragShadowBuilder+shadowBuilder+=+new+View.DragShadowBuilder(view);
++++++++view.startDrag(null,+shadowBuilder,+_myListView.getItemAtPosition(position),+0);
++++++++return+true;
++++}
});

//+Set+the+adapter+and+drag+listener
_myListView.setOnDragListener(new+MyListViewDragListener());
_myListView.setAdapter(new+MyViewAdapter(getActivity()));

//+Classes+used+above

private+class+MyViewAdapter+extends+ArrayAdapter<Object>+{
++++public+MyViewAdapter+(Context+context,+List<TimedElement>+objects)+{
++++++++super(context,+0,+objects);
++++}
++++@Override
++++public+View+getView(int+position,+View+convertView,+ViewGroup+parent)+{
++++++++View+myView+=+convertView;
++++++++if+(myView+==+null)+{
++++++++++++//+Instanciate+your+view
++++++++}
++++++++//+Associates+view+and+position+in+ListAdapter,+needed+for+drag+and+drop
++++++++myView.setId(position);
++++++++return+myView;
++++}
}


private+class+MyListViewDragListener+implements+View.OnDragListener+{
++++@Override
++++public+boolean+onDrag(View+v,+DragEvent+event)+{
++++++++final+int+action+=+event.getAction();
++++++++switch(action)+{
++++++++++++case+DragEvent.ACTION_DRAG_STARTED:
++++++++++++++++return+true;
++++++++++++case+DragEvent.ACTION_DRAG_DROP:
++++++++++++++++//+We+drag+the+item+on+top+of+the+one+which+is+at+itemPosition
++++++++++++++++int+itemPosition+=+_myListView.pointToPosition((int)event.getX(),+(int)event.getY());
++++++++++++++++//+We+can+even+get+the+view+at+itemPosition+thanks+to+get/setid
++++++++++++++++View+itemView+=+_myListView.findViewById(itemPosition+);
++++++++++++++++/*+If+you+try+the+same+thing+in+ACTION_DRAG_LOCATION,+itemView
+++++++++++++++++*+is+sometimes+null;+if+you+need+this+view,+just+return+if+null.
+++++++++++++++++*+As+the+same+event+is+then+fired+later,+only+process+the+event
+++++++++++++++++*+when+itemView+is+not+null.
+++++++++++++++++*+It+can+be+more+problematic+in+ACTION_DRAG_DROP+but+for+now
+++++++++++++++++*+I+never+had+itemView+null+in+this+event.+*/
++++++++++++++++//+Handle+the+drop+as+you+like
++++++++++++++++return+true;
+++++++++}
++++}
}|code-block|syntax|javascript|422457|现在，如果您需要在进行拖放操作时获得视觉反馈，有几种策略可供选择。例如，在您的活动中可以有两个实例变量，名为：|422458|private+boolean+ongoingDrag+=+false;+//+To+know+if+we+are+in+a+drag&drop+state
private+int+dragPosition+=+0;+//+You+put+the+itemPosition+variable+here|422459|在MyListViewDragListener中进行拖放操作时，您可以修改这些变量，并在MyViewAdapter中使用它们的状态。当然，不要忘记使用诸如_myListView.getAdapter()).notifyDataSetChanged()或_myListView.invalidate()方法之类的东西来更新UI+(当然，在事件线程中使用处理程序)。|422460|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/14118984/drag-and-drop-listview-and-item-views-that-miss-the-action-drag-started-event^0|20|4|27|E|2T|8|2|C|0|0|S|8|11|B|0|G|8|T|2|Z|C|1M|Q|2D|N|0|L|8|0|0|0|0|1|M|18|D|25|1C|3I|O|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]|$9|19|A|1A|B|C]]|D|@$9|1B|A|1C|1|1D]]|E|$]]|$1|F|3|G|5|6|7|1E|8|@$9|1F|A|1G|B|C]|$9|1H|A|1I|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|1J|8|@$9|1K|A|1L|B|C]|$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]|$9|1Q|A|1R|B|C]|$9|1S|A|1T|B|C]]|D|@]|E|$]]|$1|J|3|K|5|6|7|1U|8|@$9|1V|A|1W|B|C]]|D|@]|E|$]]|$1|L|3|M|5|N|7|1X|8|@]|D|@]|E|$O|P]]|$1|Q|3|R|5|6|7|1Y|8|@]|D|@]|E|$]]|$1|S|3|T|5|N|7|1Z|8|@]|D|@]|E|$O|P]]|$1|U|3|V|5|6|7|20|8|@$9|21|A|22|B|C]|$9|23|A|24|B|C]|$9|25|A|26|B|C]|$9|27|A|28|B|C]]|D|@]|E|$]]|$1|W|3|-4|5|6|7|29|8|@]|D|@]|E|$]]]|X|$Y|$5|Z|10|11|E|$12|13]]]]

I have the <a href="https://stackoverflow.com/questions/14118984/drag-and-drop-listview-and-item-views-that-miss-the-action-drag-started-event">same problem</a>. I did not solved this recycling problem, but I found a possible workaround still using the Drag &amp; Drop framework. The idea is to change of perspective: instead of using a <code>OnDragListener</code> on each <code>View</code> in the list, it can be used on the <code>ListView</code> directly.

Then the idea is to find on top of which item the finger is while doing the Drag &amp; Drop, and to write the related display code in the <code>ListAdapter</code> of the <code>ListView</code>. The trick is then to find on top of which item view we are, and where the drop is done.

In order to do that, I set as an <code>id</code> to each view created by the adapter its <code>ListView</code> position - with <code>View.setId()</code>, so I can find it later using a combination of <code>ListView.pointToPosition()</code> and <code>ListView.findViewById()</code>.

As a drag listener example (which is, I remind you, applied on the <code>ListView</code>), it can be something like that:

<pre><code>// Initalize your ListView
private ListView _myListView = new ListView(getContext());

// Start drag when long click on a ListView item
_myListView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
 @Override
 public boolean onItemLongClick(AdapterView&lt;?&gt; parent, View view, int position, long id) {
 DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
 view.startDrag(null, shadowBuilder, _myListView.getItemAtPosition(position), 0);
 return true;
 }
});

// Set the adapter and drag listener
_myListView.setOnDragListener(new MyListViewDragListener());
_myListView.setAdapter(new MyViewAdapter(getActivity()));

// Classes used above

private class MyViewAdapter extends ArrayAdapter&lt;Object&gt; {
 public MyViewAdapter (Context context, List&lt;TimedElement&gt; objects) {
 super(context, 0, objects);
 }
 @Override
 public View getView(int position, View convertView, ViewGroup parent) {
 View myView = convertView;
 if (myView == null) {
 // Instanciate your view
 }
 // Associates view and position in ListAdapter, needed for drag and drop
 myView.setId(position);
 return myView;
 }
}


private class MyListViewDragListener implements View.OnDragListener {
 @Override
 public boolean onDrag(View v, DragEvent event) {
 final int action = event.getAction();
 switch(action) {
 case DragEvent.ACTION_DRAG_STARTED:
 return true;
 case DragEvent.ACTION_DRAG_DROP:
 // We drag the item on top of the one which is at itemPosition
 int itemPosition = _myListView.pointToPosition((int)event.getX(), (int)event.getY());
 // We can even get the view at itemPosition thanks to get/setid
 View itemView = _myListView.findViewById(itemPosition );
 /* If you try the same thing in ACTION_DRAG_LOCATION, itemView
 * is sometimes null; if you need this view, just return if null.
 * As the same event is then fired later, only process the event
 * when itemView is not null.
 * It can be more problematic in ACTION_DRAG_DROP but for now
 * I never had itemView null in this event. */
 // Handle the drop as you like
 return true;
 }
 }
}
</code></pre>

Now if you need to have a visual feedback when doing a drag and drop, there are several strategies. You can for instance have 2 instance variables in your activity named:

<pre><code>private boolean ongoingDrag = false; // To know if we are in a drag&amp;drop state
private int dragPosition = 0; // You put the itemPosition variable here
</code></pre>

When doing the drag and drop in <code>MyListViewDragListener</code> you modify these variables, and you use their state in <code>MyViewAdapter</code>. Of course do not forget to update the UI (in the event thread of course, use a Handler) with something like <code>_myListView.getAdapter()).notifyDataSetChanged()</code> or maybe <code>_myListView.invalidate()</code> method.

blocks|key|422495|text|问题是，如果视图在被调用时不可见，则listView.getPositionForView(视图)将返回-1。因此，当你滚动列表时，依赖它将会失败。因此，您可以在列表项上设置一个listView.setOnItemLongClickListener()，以调用该项上的startDrag()，而不是设置一个view.setOnLongClickListener()。onItemLongClick()提供了可以在startDrag()的myLocalState参数中传递的位置。然后在onDrag()中使用event.getLocalState()将其恢复，并将其转换为整数。像这样..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|422496|++++listView.setOnItemLongClickListener(new+AdapterView.OnItemLongClickListener()+{
++++++++@Override
++++++++public+boolean+onItemLongClick(AdapterView<?>+parent,+View+view,+int+position,+long+id)+{
++++++++++++position+-=+listView.getHeaderViewsCount();
++++++++++++DragShadowBuilder+dragShadow+=+new+View.DragShadowBuilder(view);
++++++++++++view.startDrag(null,+dragShadow,+position,+0);
++++++++++++return+true;
++++++++}
++++});|code-block|syntax|javascript|422497|然后在你的OnDragListener中..。|422498|@Override
public+boolean+onDrag(View+eventView,+DragEvent+event)+{
++++Integer+dragViewPos+=+((Integer)+event.getLocalState());
++++int+eventViewPos+=+listView.getPositionForView(eventView)+-+listView.getHeaderViewsCount();
++++...
}|422499|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

The problem is because listView.getPositionForView(view) returns -1 if the view is not visible when it is called. So relying on that will fail when you scroll the list. So, instead of setting a view.setOnLongClickListener() you can set a listView.setOnItemLongClickListener() on the list item which calls startDrag() on the item. onItemLongClick() gives you the position which you can pass to in the myLocalState parameter of startDrag(). Then you recover that in onDrag() using event.getLocalState() and casting it to an Integer. Like this...

<pre><code> listView.setOnItemLongClickListener(new AdapterView.OnItemLongClickListener() {
 @Override
 public boolean onItemLongClick(AdapterView&lt;?&gt; parent, View view, int position, long id) {
 position -= listView.getHeaderViewsCount();
 DragShadowBuilder dragShadow = new View.DragShadowBuilder(view);
 view.startDrag(null, dragShadow, position, 0);
 return true;
 }
 });
</code></pre>

Then in your OnDragListener...

<pre><code>@Override
public boolean onDrag(View eventView, DragEvent event) {
 Integer dragViewPos = ((Integer) event.getLocalState());
 int eventViewPos = listView.getPositionForView(eventView) - listView.getHeaderViewsCount();
 ...
}
</code></pre>

I am trying to implement a drag and drop in a <code>ListView</code> in android(Ice Cream Sandwich). So when the dragged object reaches the edge of the <code>ListView</code>, I am scrolling the <code>ListView</code> in the relevant direction. The problem is that when we scroll, sometimes the adapter creates new <code>View</code>s as necessary and these 'new' <code>View</code>s did not receive the <code>ACTION_DRAG_STARTED</code> event earlier and hence do not receive the <code>DragEvent</code> updates. Is there any way I can send the events to these views as well?

Drag and Drop in a `ListView`

我正试着在安卓(冰淇淋三明治)的ListView中实现拖放。因此，当被拖动的对象到达ListView的边缘时，我将在相关方向上滚动ListView。问题是，当我们滚动时，有时适配器会根据需要创建新的View，并且这些“新的”View没有早先接收到ACTION_DRAG_STARTED事件，因此没有接收到DragEven...

问在`ListView`中拖放
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