Android RecyclerView实现拖拽排序_android recyclerview 拖动排序

布局文件

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">
    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/rv_picture"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:transcriptMode="alwaysScroll"/>
</RelativeLayout>

item_pic.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="124dp"
    android:layout_height="124dp"
    android:background="@color/white">
 
    <ImageView
        android:id="@+id/iv_picture"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scaleType="fitXY"
        android:padding="2dp"/>
</RelativeLayout>

适配器PicAdapter.class

public class PicAdapter extends RecyclerView.Adapter<PicAdapter.ViewHolder> {
 
    private Context context;
    private List<PicBean> picBeans;
 
 
    public PicAdapter(Context context, List<PicBean> picBeans) {
        this.context = context;
        this.picBeans = picBeans;
    }
 
    @Override
    public PicAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.item_pic, parent, false);
        return new ViewHolder(view);
    }
 
    @Override
    public void onBindViewHolder(PicAdapter.ViewHolder holder, int position) {
        Log.d("dddd","onBindViewHolder");
        holder.iv_picture.setImageResource(picBeans.get(position).getImage());
    }
 
    @Override
    public int getItemCount() {
        return picBeans.size();
    }
 
    public class ViewHolder extends RecyclerView.ViewHolder {
        public ImageView iv_picture;
        public ViewHolder(View itemView) {
            super(itemView);
            iv_picture = (ImageView) itemView.findViewById(R.id.iv_picture);
        }
    }
}

编写实现拖拽的帮助类MyItemTouchHelper.class，继承父类ItemTouchHelper.Callback，重写onMove{}方法，处理长按拖拽操作，对位置进行更改

public class MyItemTouchHelper extends ItemTouchHelper.Callback{
    private List<PicBean> pictureBeans;
    private PicAdapter recycleViewAdapter;
    MainActivity activity;
    public MyItemTouchHelper(MainActivity activity, List<PicBean> pictureBeans, PicAdapter recycleViewAdapter) {
        Log.d("dddd","into MyItemTouchHelper");
        this.pictureBeans = pictureBeans;
        this.recycleViewAdapter = recycleViewAdapter;
        this.activity = activity;
    }
 
    @Override
    public int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
        final int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN |ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
        final int swipeFlags = 0;
        return makeMovementFlags(dragFlags, swipeFlags);
    }
 
    @Override
    public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
        recyclerView.getParent().requestDisallowInterceptTouchEvent(true);
        //得到当拖拽的viewHolder的Position
        int fromPosition = viewHolder.getAdapterPosition();
        //拿到当前拖拽到的item的viewHolder
        int toPosition = target.getAdapterPosition();
        if (fromPosition < toPosition) {
            for (int i = fromPosition; i < toPosition; i++) {
                Collections.swap(pictureBeans, i, i + 1);
            }
        } else {
            for (int i = fromPosition; i > toPosition; i--) {
                Collections.swap(pictureBeans, i, i - 1);
            }
        }
        recycleViewAdapter.notifyItemMoved(fromPosition, toPosition);
        Log.d("dddd"," fromPosition = "+fromPosition+" toPosition"+toPosition);
        return true;
    }
 
    @Override
    public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
 
    }
 
    /**
     * 长按选中Item时修改颜色
     *
     * @param viewHolder
     * @param actionState
     */
    @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP)
    @Override
    public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
        //if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
        //viewHolder.itemView.setBackground(getDrawable(R.drawable.card_drag_selected));
        //}
        super.onSelectedChanged(viewHolder, actionState);
    }
 
    /**
     * 手指松开的时候还原颜色
     * @param recyclerView
     * @param viewHolder
     */
    @RequiresApi(api = Build.VERSION_CODES.M)
    @Override
    public void clearView(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);
        //viewHolder.itemView.setBackground(getDrawable(R.drawable.card));
    }
 
    /**
     * 重写拖拽不可用
     * @return
     */
    @Override
    public boolean isLongPressDragEnabled() {
        return true;
    }
}

主界面MainActivity.class

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private com.example.dragdemo.PicAdapter picAdapter;
    private List<com.example.dragdemo.PicBean> picBeans;
    private ItemTouchHelper mItemTouchHelper;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        //模拟数据
        picBeans = new ArrayList<>();
        int image = 0;
        for (int i = 0;i<12;i++){
            com.example.dragdemo.PicBean picBean = new com.example.dragdemo.PicBean();
            if (i % 3 == 0){
                image = R.color.black;
            }else if (i % 3 == 1){
                image = R.color.purple_200;
            }else if (i % 3 == 2){
                image = R.color.teal_700;
            }
            Log.d("dddd","image = "+image);
            picBean.setImage(image);
            picBeans.add(picBean);
        }
        Log.d("dddd","picBeans.size() =  "+picBeans.size());
 
        recyclerView = (RecyclerView)findViewById(R.id.rv_picture);
 
        GridLayoutManager gridLayoutManager = new GridLayoutManager(this, 3);
        recyclerView.setLayoutManager(gridLayoutManager);
        recyclerView.setNestedScrollingEnabled(true);
 
        //创建并设置适配器
        picAdapter = new PicAdapter(this,picBeans);
        recyclerView.setAdapter(picAdapter);
 
       //添加拖拽事件
        mItemTouchHelper = new ItemTouchHelper(new MyItemTouchHelper(this,picBeans,picAdapter));
        mItemTouchHelper.attachToRecyclerView(recyclerView);
    }
}

到这里，我们的RecyclerView拖拽排序功能就完成啦 

接下来可以看一下效果：