Recyclerview进阶——元素拖拽及侧滑删除_recyclerview拖拽

之前一直觉得列表的拖拽换位和侧滑删除是很难实现的，不过之后参考了下几篇博客后发，发现还是很简单的，因为suppor早就封装好了，最主要的是继承ItemTouchHelper.Callback，并对其方法

效果图如下：

步骤如下：

1、新建类并继承ItemTouchHelper.Callback，在其对应方法设置相应操作包括，不同布局的拖拽和侧滑删除，选择效果

2、Adapter中实现自定义的监听回调，对位置交换和删除动作做对应的数据操作和界面的刷新

3、主代码中 新建ItemTouchHelper 并关联RecyclerView即可

代码如下：

1、新建类并继承ItemTouchHelper.Callback，在其对应方法设置相应操作

public interface ItemTouchHelperAdapter {
    //数据交换
    void onItemMove(int fromPosition,int toPosition);
    //数据删除
    void onSwiped(int position);
}

public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback {
 
    private ItemTouchHelperAdapter mAdapter;
    private boolean dragEnabled;        //能否拖拽
    private boolean swipeEnabled;       //能否侧滑
 
 
    public SimpleItemTouchHelperCallback(ItemTouchHelperAdapter adapter, boolean dragEnabled, boolean swipeEnabled) {
        mAdapter = adapter;
        this.dragEnabled = dragEnabled;
        this.swipeEnabled = swipeEnabled;
    }
 
    //同来设置 拖拽移动，或移动删除
    @Override
    public int getMovementFlags(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder) {
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {// GridLayoutManager
            // flag如果值是0，相当于这个功能被关闭
            int dragFlag = ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT | ItemTouchHelper.UP | ItemTouchHelper.DOWN;
            int swipeFlag = 0;
            // create make
            return makeMovementFlags(dragFlag, swipeFlag);
        } else if (layoutManager instanceof LinearLayoutManager) {// linearLayoutManager
            LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
            int orientation = linearLayoutManager.getOrientation();
 
            int dragFlag = 0;
            int swipeFlag = 0;
 
            // 为了方便理解，相当于分为横着的ListView和竖着的ListView
            if (orientation == LinearLayoutManager.HORIZONTAL) {// 如果是横向的布局
                swipeFlag = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
                dragFlag = ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
            } else if (orientation == LinearLayoutManager.VERTICAL) {// 如果是竖向的布局，相当于ListView
                dragFlag = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
                swipeFlag = ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
            }
            return makeMovementFlags(dragFlag, swipeFlag);
        }
        return 0;
    }
 
    //是否能拖动
    @Override
    public boolean isLongPressDragEnabled() {
        return dragEnabled;
    }
 
    //是否能侧滑
    @Override
    public boolean isItemViewSwipeEnabled() {
        return swipeEnabled;
    }
 
    //拖动
    @Override
    public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {
        Log.e(TAG, "onMove");
//        if (viewHolder.getAdapterPosition() == 0) {
            //第一个无法拖拽
//            return false;
//        }
        mAdapter.onItemMove(viewHolder.getAdapterPosition(), target.getAdapterPosition());
        return true;
    }
 
    //左右滑动
    @Override
    public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {
        mAdapter.onSwiped(viewHolder.getAdapterPosition());
        Log.e(TAG, "onSwiped");
    }
 
    //选中项操作
    @Override
    public void onSelectedChanged(@Nullable RecyclerView.ViewHolder viewHolder, int actionState) {
        super.onSelectedChanged(viewHolder, actionState);
        Log.e(TAG, "onSelectedChanged");
 
        if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {
            if (viewHolder != null)
                viewHolder.itemView.setBackgroundColor(Color.LTGRAY);
        }
    }
 
    //释放选中项操作
    @Override
    public void clearView(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);
        Log.e(TAG, "clearView");
        viewHolder.itemView.setBackgroundColor(0);
    }
}

2、Adapter中实现自定义的监听回调

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.Holder> implements ItemTouchHelperAdapter {
 
    private Context mContext;
    private List<String> mList;
 
    public MyAdapter(Context context, List<String> list) {
        mContext = context;
        mList = list;
    }
 
    @NonNull
    @Override
    public Holder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        return new Holder(LayoutInflater.from(mContext).inflate(R.layout.item_test, viewGroup, false));
    }
 
    @Override
    public void onBindViewHolder(@NonNull final Holder holder, final int i) {
        holder.tvF.setText(mList.get(i));
        holder.tvS.setText(mList.get(i));
        holder.delete.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //移除数据
                mList.remove(i);
                notifyDataSetChanged();
            }
        });
    }
 
    @Override
    public int getItemCount() {
        return mList.size();
    }
 
    @Override
    public void onItemMove(int fromPosition, int toPosition) {
        //交换位置
        Collections.swap(mList, fromPosition, toPosition);
        notifyItemMoved(fromPosition, toPosition);
    }
 
    @Override
    public void onSwiped(int position) {
        //移除数据
        mList.remove(position);
        notifyItemRemoved(position);
    }
 
    static class Holder extends RecyclerView.ViewHolder {
        private TextView tvF;
        private TextView tvS;
        private ImageView delete;
 
        public Holder(@NonNull View itemView) {
            super(itemView);
            tvF = itemView.findViewById(R.id.tv_first);
            tvS = itemView.findViewById(R.id.tv_second);
            delete = itemView.findViewById(R.id.delete);
        }
    }
}

3、主代码中 新建ItemTouchHelper 并关联RecyclerView

public class MainActivity extends AppCompatActivity {
 
    public static final String TAG = "recyclerviewmove";
    private Button btnChange;
    private RecyclerView mRecyclerView;
    private MyAdapter mMyAdapter;
 
    private List<String> mList = new ArrayList<>();
    private boolean bGrid;      //布局标识
 
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
 
        for (int i = 0; i < 9; i++) {
            mList.add(i + "" + i + "" + i);
        }
        mRecyclerView = findViewById(R.id.recycler_view);
        btnChange = findViewById(R.id.btn_change);
 
        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));
        mMyAdapter = new MyAdapter(this, mList);
        mRecyclerView.setAdapter(mMyAdapter);
        //关联ItemTouchHelper和RecyclerView
        ItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(mMyAdapter,true,true);
        ItemTouchHelper touchHelper = new ItemTouchHelper(callback);
        touchHelper.attachToRecyclerView(mRecyclerView);
 
        btnChange.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (bGrid) {
                    mRecyclerView.setLayoutManager(new LinearLayoutManager(MainActivity.this));
                } else {
                    mRecyclerView.setLayoutManager(new GridLayoutManager(MainActivity.this, 4));
                }
                bGrid = !bGrid;
            }
        });
    }
}

参考：RecyclerView进阶：使用ItemTouchHelper实现拖拽和侧滑删除_recyclerview把item可以拖拽到任意地方具体实现_程序员的自我反思的博客-CSDN博客