Interface to listen for drag and swipe events from an ItemTouchHelper.Callback

ItemTouchHelperAdapter.java

/*
 * Copyright (C) 2015 Paul Burke
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package co.paulburke.android.itemtouchhelperdemo.helper;

import android.support.v7.widget.RecyclerView;
import android.support.v7.widget.helper.ItemTouchHelper;

/**
 * Interface to listen for a move or dismissal event from a {@link ItemTouchHelper.Callback}.
 *
 * @author Paul Burke (ipaulpro)
 */
public interface ItemTouchHelperAdapter {

    /**
     * Called when an item has been dragged far enough to trigger a move. This is called every time
     * an item is shifted, and <strong>not</strong> at the end of a "drop" event.<br/>
     * <br/>
     * Implementations should call {@link RecyclerView.Adapter#notifyItemMoved(int, int)} after
     * adjusting the underlying data to reflect this move.
     *
     * @param fromPosition The start position of the moved item.
     * @param toPosition   Then resolved position of the moved item.
     *
     * @see RecyclerView#getAdapterPositionFor(RecyclerView.ViewHolder)
     * @see RecyclerView.ViewHolder#getAdapterPosition()
     */
    void onItemMove(int fromPosition, int toPosition);


    /**
     * Called when an item has been dismissed by a swipe.<br/>
     * <br/>
     * Implementations should call {@link RecyclerView.Adapter#notifyItemRemoved(int)} after
     * adjusting the underlying data to reflect this removal.
     *
     * @param position The position of the item dismissed.
     *
     * @see RecyclerView#getAdapterPositionFor(RecyclerView.ViewHolder)
     * @see RecyclerView.ViewHolder#getAdapterPosition()
     */
    void onItemDismiss(int position);
}

void onItemDismiss(int position);
should return boolean?
the same in article

Nicely commented! It's a sad state of affairs that documentarian like you are the exception instead of the rule.

Thanks! It has been really helpful.

Kotlin version

package com.example.dragndropgrid

import androidx.recyclerview.widget.ItemTouchHelper
import androidx.recyclerview.widget.RecyclerView


/**
 * Interface to listen for a move or dismissal event from a [ItemTouchHelper.Callback].
 *
 * @author Paul Burke (ipaulpro)
 */
interface ItemTouchHelperAdapter {
    /**
     * Called when an item has been dragged far enough to trigger a move. This is called every time
     * an item is shifted, and **not** at the end of a "drop" event.<br></br>
     * <br></br>
     * Implementations should call [RecyclerView.Adapter.notifyItemMoved] after
     * adjusting the underlying data to reflect this move.
     *
     * @param fromPosition The start position of the moved item.
     * @param toPosition   Then resolved position of the moved item.
     *
     * @see RecyclerView.getAdapterPositionFor
     * @see RecyclerView.ViewHolder.getAdapterPosition
     */
    fun onItemMove(fromPosition: Int, toPosition: Int)

    /**
     * Called when an item has been dismissed by a swipe.<br></br>
     * <br></br>
     * Implementations should call [RecyclerView.Adapter.notifyItemRemoved] after
     * adjusting the underlying data to reflect this removal.
     *
     * @param position The position of the item dismissed.
     *
     * @see RecyclerView.getAdapterPositionFor
     * @see RecyclerView.ViewHolder.getAdapterPosition
     */
    fun onItemDismiss(position: Int)
}

Even in 2023, this alone was GOLD: " * Called when an item has been dragged far enough to trigger a move. This is called every time
* an item is shifted, and not at the end of a "drop" event." I've been trying to get my head around this stuff for weeks and this was NEVER made clear until now.