RecycleView实现侧滑删除item

对于列表空间的侧滑操作，网上有很多开源的空间可以使用，Google在它的新控件RecycleView中增加了侧滑的API,完全遵循Material Design设计规范，下面看看效果演示：

下面看看介绍一下刷新控制类： ItemTouchHelper。

顾名思义，这个类就是来帮助我们对于item执行更多的操作。下面看看具体操作：

我们实例化这个类的时候需要传入对应的会掉接口：

/**

     * Creates an ItemTouchHelper that will work with the given Callback.

     * <p>

     * You can attach ItemTouchHelper to a RecyclerView via

     * {@link #attachToRecyclerView(RecyclerView)}. Upon attaching, it will add an item decoration,

     * an onItemTouchListener and a Child attach / detach listener to the RecyclerView.

     *

     * @param callback The Callback which controls the behavior of this touch helper.

     */

    public ItemTouchHelper(Callback callback) {

        mCallback = callback;

    }

看源码会发现这个接口是个抽象类，我们看看ItemTouchHelper中写了一个抽象类继承与该抽象类：

  /**

         * Creates a Callback for the given drag and swipe allowance. These values serve as

         * defaults

         * and if you want to customize behavior per ViewHolder, you can override

         * {@link #getSwipeDirs(RecyclerView, ViewHolder)}

         * and / or {@link #getDragDirs(RecyclerView, ViewHolder)}.

         *

         * @param dragDirs  Binary OR of direction flags in which the Views can be dragged. Must be

         *                  composed of {@link #LEFT}, {@link #RIGHT}, {@link #START}, {@link

         *                  #END},

         *                  {@link #UP} and {@link #DOWN}.

         * @param swipeDirs Binary OR of direction flags in which the Views can be swiped. Must be

         *                  composed of {@link #LEFT}, {@link #RIGHT}, {@link #START}, {@link

         *                  #END},

         *                  {@link #UP} and {@link #DOWN}.

         */

        public SimpleCallback(int dragDirs, int swipeDirs) {

            mDefaultSwipeDirs = swipeDirs;

            mDefaultDragDirs = dragDirs;

        }

在实现了它的适合需要传入两个参数，一个是拖出来的方向以及滑动的方向，通常我们只需要指定后者的参数，前置置为0即可。以下是可选参数。

 /**

     * Up direction, used for swipe & drag control.

     */

    public static final int UP = ;

    /**

     * Down direction, used for swipe & drag control.

     */

    public static final int DOWN =  << ;

    /**

     * Left direction, used for swipe & drag control.

     */

    public static final int LEFT =  << ;

    /**

     * Right direction, used for swipe & drag control.

     */

    public static final int RIGHT =  << ;

当我们实现了这个抽象类之后需要复写它的三个方法，当然也可以继承于它。接下来是具体实现代码。

 ItemTouchHelper touchHelper = new ItemTouchHelper(new ItemTouchHelper.SimpleCallback(0, ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT) {

            @Override

            public boolean onMove(RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, RecyclerView.ViewHolder target) {

                //滑动时的一些操作

                isDelete = false;

                return true;

            }

            @Override

            public void onSwiped(RecyclerView.ViewHolder viewHolder, int direction) {

                // 处理滑动事件回调

                final int pos = viewHolder.getAdapterPosition();

                ImActiveChat imActiveChat = imActiveChatList.get(pos);

                imActiveChatList.remove(pos);

                chatRVAdapter.notifyItemRemoved(pos);

                if (imActiveChatList.size()==0){

                    rvSingleChat.setVisibility(View.GONE);

                    tvNoMessage.setVisibility(View.VISIBLE);

                }

                String text;

                isDelete = true;

                // 判断方向，进行不同的操作

                if (direction == ItemTouchHelper.RIGHT) {

                    text = "删除了和" + imActiveChat.getUserId() + "的聊天";

                } else {

                    text = "删除了和" + imActiveChat.getUserId() + "的聊天";

                }

                Snackbar.make(viewHolder.itemView, text, Snackbar.LENGTH_SHORT)

                        .setAction("取消", v -> {

                            imActiveChatList.add(pos, imActiveChat);

                            chatRVAdapter.notifyItemInserted(pos);

                            isDelete = false;

                        }).setCallback(new Snackbar.Callback() {

                    @Override

                    public void onDismissed(Snackbar snackbar, int event) {

                        super.onDismissed(snackbar, event);

                        if (isDelete) {

                            StorageImActiveChat.getInstance((Application) UiUtils.getContext()).deleteAChatRoom(imActiveChat);

                            //未读消息删除

                            Flowable.fromCallable(() -> StorageImMessage.getInstance(QNApplication.getContext()).findMessageById(imActiveChat.getUserId(), 100)).subscribeOn(Schedulers.io())

                                    .observeOn(AndroidSchedulers.mainThread())

                                    .subscribe(SingleChatListFragment.this::setMessageReaded);

                        }

                    }

                }).show();

            }

            //处理动画

            @Override

            public void onChildDraw(Canvas c, RecyclerView recyclerView, RecyclerView.ViewHolder viewHolder, float dX, float dY, int actionState, boolean isCurrentlyActive) {

                if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {

                    //滑动时改变 Item 的透明度，以实现滑动过程中实现渐变效果

                    final float alpha = 1 - Math.abs(dX) / (float) viewHolder.itemView.getWidth();

                    viewHolder.itemView.setAlpha(alpha);

                    viewHolder.itemView.setTranslationX(dX);

                } else {

                    super.onChildDraw(c, recyclerView, viewHolder, dX, dY, actionState, isCurrentlyActive);

                }

            }

            //滑动事件完成时回调

            //在这里可以实现撤销操作

            //是否长按进行拖拽

            @Override

            public boolean isLongPressDragEnabled() {

                return true;

            }

        });

        touchHelper.attachToRecyclerView(recycleview);

onMove在滑动结束的时候调用，而onSwip在滑动的时候调用。实现的逻辑需要自己编写，实现起来也不困难。

巴特西

RecycleView实现侧滑删除item

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