代码在我的Activity中工作，但不在我的Fragment中。我可以看到那里的元素，但是我不能拖放它们，它会在长按中停止。
有人可以提供解决方案吗？
错误日志：
*E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.future.buildingautomationsystem, PID: 10526
java.lang.NullPointerException
at com.example.future.buildingautomationsystem.slidefragment.onItemLongClick(slidefragment.java:179)
at android.widget.AbsListView.performLongPress(AbsListView.java:3175)
at android.widget.AbsListView$CheckForLongPress.run(AbsListView.java:3124)
at android.os.Handler.handleCallback(Handler.java:808)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:5395)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:837)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:653)
at dalvik.system.NativeStart.main(Native Method)*
代码：
import java.util.ArrayList;
import android.app.Activity;
import android.app.Fragment;
import android.content.ClipData;
import android.content.ClipDescription;
import android.os.Bundle;
import android.os.Handler;
import android.view.DragEvent;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.View.OnDragListener;
import android.view.View.OnLongClickListener;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemLongClickListener;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;
public class slidefragment extends Fragment implements OnDragListener,
OnItemLongClickListener {
ArrayList drawables;
private BaseAdapter adapter;
private int draggedIndex = -1;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// TODO Auto-generated method stub
View v;
v = inflater.inflate(R.layout.slidefragment, container,false);
super.onCreate(savedInstanceState);
drawables = new ArrayList();
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
drawables.add(R.drawable.ico1);
GridView gridView = (GridView) v.findViewById(R.id.grid_view);
gridView.setOnItemLongClickListener(slidefragment.this);
gridView.setAdapter(adapter = new BaseAdapter() {
@Override
// Get a View that displays the data at the specified position in
// the data set.
public View getView(int position, View convertView,
ViewGroup gridView) {
// try to reuse the views.
ImageView view = (ImageView) convertView;
// if convert view is null then create a new instance else reuse
// it
if (view == null) {
view = new ImageView(getActivity().getBaseContext());
}
view.setImageResource((Integer) drawables.get(position));
view.setTag(String.valueOf(position));
return view;
}
@Override
// Get the row id associated with the specified position in the
// list.
public long getItemId(int position) {
return position;
}
@Override
// Get the data item associated with the specified position in the
// data set.
public Object getItem(int position) {
return drawables.get(position);
}
@Override
// How many items are in the data set represented by this Adapter.
public int getCount() {
return drawables.size();
}
});
return v;
}
// @Override
// public boolean onCreateOptionsMenu(Menu menu) {
// getMenuInflater().inflate(R.menu.menu_login,getView().menu);
// return true;
//}
@Override
public boolean onDrag(final View view, DragEvent dragEvent) {
switch (dragEvent.getAction()) {
case DragEvent.ACTION_DRAG_STARTED:
// Drag has started
// If called for trash resize the view and return true
if (view.getId() == R.id.droplayout) {
view.animate().scaleX(1.0f);
view.animate().scaleY(1.0f);
return true;
} else // else check the mime type and set the view visibility
if (dragEvent.getClipDescription().hasMimeType(
ClipDescription.MIMETYPE_TEXT_PLAIN)) {
view.setVisibility(View.GONE);
return true;
} else {
return false;
}
case DragEvent.ACTION_DRAG_ENTERED:
// Drag has entered view bounds
// If called for trash can then scale it.
if (view.getId() == R.id.droplayout) {
view.animate().scaleX(1.5f);
view.animate().scaleY(1.5f);
}
return true;
case DragEvent.ACTION_DRAG_EXITED:
// Drag exited view bounds
// If called for trash can then reset it.
if (view.getId() == R.id.droplayout) {
view.animate().scaleX(1.0f);
view.animate().scaleY(1.0f);
}
view.invalidate();
return true;
case DragEvent.ACTION_DRAG_LOCATION:
// Ignore this event
return true;
case DragEvent.ACTION_DROP:
// Dropped inside view bounds
// If called for trash can then delete the item and reload the grid
// view
if (view.getId() == R.id.droplayout) {
drawables.remove(draggedIndex);
draggedIndex = -1;
}
adapter.notifyDataSetChanged();
case DragEvent.ACTION_DRAG_ENDED:
// Hide the trash can
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
view. findViewById(R.id.droplayout).setVisibility(View.GONE);
}
}, 1000l);
if (view.getId() == R.id.droplayout) {
view.animate().scaleX(1.0f);
view.animate().scaleY(1.0f);
} else {
view.setVisibility(View.VISIBLE);
}
// remove drag listeners
view.setOnDragListener(null);
return true;
}
return false;
}
@Override
public boolean onItemLongClick(AdapterView gridView, View view,
int position, long row) {
ClipData.Item item = new ClipData.Item((String) view.getTag());
ClipData clipData = new ClipData((CharSequence) view.getTag(),
new String[] { ClipDescription.MIMETYPE_TEXT_PLAIN }, item);
view.startDrag(clipData, new View.DragShadowBuilder(view), null, 0);
View trashCan = view.findViewById(R.id.linearlayoutbottom);
trashCan.setVisibility(View.VISIBLE);
trashCan.setOnDragListener(slidefragment.this);
trashCan.setOnDragListener(slidefragment.this);
draggedIndex = position;
return true;
}
public LayoutInflater getMenuInflater() {
return getMenuInflater();
}
}