public void removeItem(int pos){
    this.mDatas.remove(pos);
    notifyItemRemoved(pos);
  }

  public void removeItem(int pos){
    this.mDatas.remove(pos);
    notifyItemRemoved(pos);
    if(pos != mDatas.size()){ // 如果移除的是最后一个，忽略
      notifyItemRangeChanged(pos, mDatas.size() - pos);
    }
  }

public class Set_Music extends ListActivity implements OnItemLongClickListener{

getListView().setOnItemLongClickListener(this);

public boolean onItemLongClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
String str = list.get(arg2).get("name");

list.remove(arg2);

adapter.notifyDataSetChanged();