RecyclerView实现拖动调整Item位置，侧滑删除Item功能

实现长按条目调整位置和侧滑删除功能，核心是ItemTouchHelper类，直接贴代码了。

DefaultItemTouchHelper

public class DefaultItemTouchHelper extends ItemTouchHelper {
    private DefaultItemTouchHelperCallback mDefaultItemTouchHelperCallback;
    private OnItemMoveListenter itemMoveListenter;


    public DefaultItemTouchHelper() {
        this(new DefaultItemTouchHelperCallback());
    }

    private DefaultItemTouchHelper(DefaultItemTouchHelperCallback callback) {
        super(callback);
        this.mDefaultItemTouchHelperCallback = callback;
    }

    public void setItemMoveListenter(OnItemMoveListenter itemMoveListenter) {
        mDefaultItemTouchHelperCallback.setCallback(itemMoveListenter);
    }

    /**
     * 是否可以滑动删除
     * @param b
     */
    public void setItemViewSwipeEnabled(boolean b) {
        mDefaultItemTouchHelperCallback.setItemViewSwipeEnabled(b);
    }
    /**
        *是否可以长按
        */
    public void setLongPressDragEnabled(boolean b) {
        mDefaultItemTouchHelperCallback.setLongPressDragEnabled(b);
    }
}

DefaultItemTouchHelperCallback

public class DefaultItemTouchHelperCallback extends ItemTouchHelper.Callback {
    private OnItemMoveListenter callback;
    private boolean isLongPressDragEnabled;
    private boolean isItemViewSwipeEnabled;

    public void setCallback(OnItemMoveListenter callback) {
        this.callback = callback;
    }
    /**
     * 返回一个复合标志，该标志定义每个状态下启用的移动方向
     * @param recyclerView
     * @param viewHolder
     * @return
     */
    @Override
    public int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
        RecyclerView.LayoutManager layoutManager = recyclerView.getLayoutManager();
        if (layoutManager instanceof GridLayoutManager) {
            LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
            if (linearLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
                int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
                int swipeFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
                return makeMovementFlags(dragFlags, swipeFlags);
            } else {
                int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
                int swipeFlags = ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
                return makeMovementFlags(dragFlags, swipeFlags);
            }
        } else if (layoutManager instanceof LinearLayoutManager) {
            LinearLayoutManager linearLayoutManager = (LinearLayoutManager) layoutManager;
            if (linearLayoutManager.getOrientation() == LinearLayoutManager.HORIZONTAL) {
                int dragFlags = ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
                int swipeFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
                return makeMovementFlags(dragFlags, swipeFlags);
            } else {
                int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
                int swipeFlags = ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
                return makeMovementFlags(dragFlags, swipeFlags);
            }
        }
        return  makeMovementFlags(0,0);
    }

    /**
     * 当ItemTouchHelper希望将拖动的项从原来的位置移动到新位置
     * @param recyclerView
     * @param viewHolder
     * @param target
     * @return
     */
    @Override
    public boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {
        if (callback!=null){
            return callback.onItemMove(viewHolder,target);
        }
        return false;
    }

    /**
     * 当用户滑动ViewHolder时调用
     * @param viewHolder
     * @param direction
     */
    @Override
    public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {
        if (callback!=null){
            callback.onItemSwipe(viewHolder,direction);
        }
    }

    /**
     * 拖动过程中状态变化的监听
     * ItemTouchHelper.ACTION_STATE_IDLE--闲置状态
     * ItemTouchHelper.ACTION_STATE_SWIPE--刷新状态
     * ItemTouchHelper.ACTION_STATE_DRAG--拖动状态
     * @param viewHolder
     * @param actionState
     */
    @Override
    public void onSelectedChanged(@Nullable RecyclerView.ViewHolder viewHolder, int actionState) {
        super.onSelectedChanged(viewHolder, actionState);
        if (callback!=null && actionState != ItemTouchHelper.ACTION_STATE_IDLE){
            callback.onSelectedChanged(viewHolder,actionState);
        }
    }

    /**
     * 完成交互后，调用
     * @param recyclerView
     * @param viewHolder
     */
    @Override
    public void clearView(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {
        super.clearView(recyclerView, viewHolder);
        if (callback!=null ){
            callback.onSelectedChanged(viewHolder,ItemTouchHelper.ACTION_STATE_IDLE);
        }
    }

    public void setLongPressDragEnabled(boolean canDrag) {
        this.isLongPressDragEnabled = canDrag;
    }

    @Override
    public boolean isLongPressDragEnabled() {
        return isLongPressDragEnabled;
    }

    public void setItemViewSwipeEnabled(boolean canSwipe) {
        this.isItemViewSwipeEnabled = canSwipe;
    }

    @Override
    public boolean isItemViewSwipeEnabled() {
        return isItemViewSwipeEnabled;
    }
}

OnItemMoveListenter

public interface OnItemMoveListenter {
    boolean onItemMove(RecyclerView.ViewHolder srcHolder, RecyclerView.ViewHolder targetHolder);
    void onItemSwipe(RecyclerView.ViewHolder srcHolder, int direction);
    void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState);
}

SwipeRecycleViewActivity

public class SwipeRecycleViewActivity extends AppCompatActivity {

    private SwipeRecyclerView mRecyclerView;
    private RecycleItemAdapter mAdapter;
    private ArrayList strings;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_swipe_recycle_view);
        mRecyclerView = findViewById(R.id.recycle_view);
        mRecyclerView.setLayoutManager(createLayoutManager());
        mRecyclerView.addItemDecoration(createItemDecoration());
        // 长按拖拽，默认关闭
        mRecyclerView.setLongPressDragEnabled(true);
        // 滑动删除，默认关闭
        mRecyclerView.setItemViewSwipeEnabled(true);
        mRecyclerView.setOnItemMoveListener(new OnItemMoveListenter() {
            @Override
            public boolean onItemMove(RecyclerView.ViewHolder srcHolder, RecyclerView.ViewHolder targetHolder) {
                if (srcHolder.getItemViewType() != targetHolder.getItemViewType()) {
                    return false;
                }
                int fromPosition = srcHolder.getAdapterPosition();
                int toPosition = targetHolder.getAdapterPosition();
                Collections.swap(strings, fromPosition, toPosition);
                mAdapter.notifyItemMoved(fromPosition, toPosition);
                // 返回true表示处理了并可以换位置，返回false表示你没有处理并不能换位置
                return true;
            }

            @Override
            public void onItemSwipe(RecyclerView.ViewHolder srcHolder, int direction) {
                //左滑、右滑 删除，如果要一个方向删除，getMovementFlags方法中处理
                int adapterPosition = srcHolder.getAdapterPosition();
                mAdapter.notifyItemRemoved(adapterPosition);
            }

            @Override
            public void onSelectedChanged(RecyclerView.ViewHolder viewHolder, int actionState) {
                if (actionState == ItemTouchHelper.ACTION_STATE_DRAG) {
                    // 拖拽的时候添加一个背景
                    viewHolder.itemView.setBackgroundColor(ContextCompat.getColor(SwipeRecycleViewActivity.this, R.color.white_pressed));
                } else if (actionState == ItemTouchHelper.ACTION_STATE_SWIPE) {
                } else if (actionState == ItemTouchHelper.ACTION_STATE_IDLE) {
                    // 在手松开的时候还原背景
                    ViewCompat.setBackground(viewHolder.itemView, ContextCompat.getDrawable(SwipeRecycleViewActivity.this, R.color.white));
                }
            }
        });
        makeDataList();
        mAdapter = new RecycleItemAdapter(this,strings);
        mRecyclerView.setAdapter(mAdapter);
    }
    private ArrayList makeDataList(){
        strings = new ArrayList<>();
        for (int i=0;i<10;i++){
            strings.add("条目-"+i);
        }
        return strings;
    }
    /**
     * 布局管理类
     *
     * @return
     */
    protected RecyclerView.LayoutManager createLayoutManager() {
        return new LinearLayoutManager(this);
    }

    /**
     * 条目效果类
     * @return
     */
    protected RecyclerView.ItemDecoration createItemDecoration() {
        return new SimplePaddingDecoration(this);
    }
    /**
     * 添加条目的间隔效果
     */
    public class SimplePaddingDecoration extends RecyclerView.ItemDecoration {
        private int dividerHeight;

        public SimplePaddingDecoration(Context context) {
            dividerHeight = 5;
        }

        @Override
        public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
            super.getItemOffsets(outRect, view, parent, state);
            //类似加了一个bottom padding
            outRect.bottom = dividerHeight;
        }
    }
}

RecyclerItemAdapter

public class RecyclerItemAdapter extends RecyclerView.Adapter {
    private ArrayList mData;
    private Context mContext;

    public RecyclerItemAdapter(Context mContext, ArrayList mData) {
        this.mData = mData;
        this.mContext = mContext;
    }

    @NonNull
    @Override
    public RecyclerItemAdapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        ViewHolder viewHolder = new ViewHolder(View.inflate(mContext, R.layout.item_drag_touch, null));
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerItemAdapter.ViewHolder holder, int position) {
        holder.tvTitle.setText(mData.get(position));
    }

    @Override
    public int getItemCount() {
        return mData.size();
    }
    static class ViewHolder extends RecyclerView.ViewHolder{
        private TextView tvTitle;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            tvTitle=itemView.findViewById(R.id.tv_title);
        }
    }
}

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