本文主要是介绍使用RecyclerView实现item拖拽变换位置重新排序，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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今天用RecyclerView实现一个拖拽交换位置，和编辑删除的功能。先来个效果图看一下
1、定义一个ItemTouchHelperAdapter接口
import androidx.recyclerview.widget.RecyclerView;/*** Created by WJY.* Date: 2021-03-16* Time: 10:45* Description: 定义RecycleView的Adapter和SimpleItemTouchHelperCallback直接交互的接口方法*/
public interface ItemTouchHelperAdapter {//数据交换void onItemMove(RecyclerView.ViewHolder source, RecyclerView.ViewHolder target);//数据删除void onItemDissmiss(RecyclerView.ViewHolder source);//drag或者swipe选中void onItemSelect(RecyclerView.ViewHolder source);//状态清除void onItemClear(RecyclerView.ViewHolder source);
}2、定义SimpleItemTouchHelperCallback类来处理RecycleView的选中、拖拽移动、拖拽删除等的实现
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.RecyclerView;/*** Created by WJY.* Date: 2021-03-16* Time: 10:50* Description: 处理RecycleView的选中,拖拽移动,拖拽删除的实现类*/
public class SimpleItemTouchHelperCallback extends ItemTouchHelper.Callback {private ItemTouchHelperAdapter mAdapter;public SimpleItemTouchHelperCallback(ItemTouchHelperAdapter adapter) {mAdapter = adapter;}@Overridepublic int getMovementFlags(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {//int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN; //允许上下的拖动//int dragFlags =ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT; //允许左右的拖动//int swipeFlags = ItemTouchHelper.LEFT; //只允许从右向左侧滑//int swipeFlags = ItemTouchHelper.DOWN; //只允许从上向下侧滑//一般使用makeMovementFlags(int,int)或makeFlag(int, int)来构造我们的返回值//makeMovementFlags(dragFlags, swipeFlags)int dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN | ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT; //允许上下左右的拖动return makeMovementFlags(dragFlags, 0);}@Overridepublic boolean onMove(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder, @NonNull RecyclerView.ViewHolder target) {//通过接口传递拖拽交换数据的起始位置和目标位置的ViewHoldermAdapter.onItemMove(viewHolder, target);return true;}@Overridepublic boolean isLongPressDragEnabled() {return true;//长按启用拖拽}@Overridepublic boolean isItemViewSwipeEnabled() {return false; //不启用拖拽删除}@Overridepublic void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) {//移动删除回调,如果不用可以不用理// mAdapter.onItemDissmiss(viewHolder);}@Overridepublic void onSelectedChanged(@Nullable RecyclerView.ViewHolder viewHolder, int actionState) {super.onSelectedChanged(viewHolder, actionState);if (actionState != ItemTouchHelper.ACTION_STATE_IDLE) {//当滑动或者拖拽view的时候通过接口返回该ViewHoldermAdapter.onItemSelect(viewHolder);}}@Overridepublic void clearView(@NonNull RecyclerView recyclerView, @NonNull RecyclerView.ViewHolder viewHolder) {super.clearView(recyclerView, viewHolder);if (!recyclerView.isComputingLayout()) {//当需要清除之前在onSelectedChanged或者onChildDraw,onChildDrawOver设置的状态或者动画时通过接口返回该ViewHoldermAdapter.onItemClear(viewHolder);}}
}
3、写我们的拖拽adapter类DragRecyclerViewAdapter
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;import com.example.test1.R;import java.util.ArrayList;
import java.util.Collections;
import java.util.List;/*** Created by WJY.* Date: 2021-03-16* Time: 10:24* Description: 拖拽的recyclerView 的 adapter*/
public class DragRecyclerViewAdapter extends RecyclerView.Adapter<DragRecyclerViewAdapter.DragHolder> implements ItemTouchHelperAdapter {private Context context;private List<String> contentList = new ArrayList<>();private boolean isShowDelete = false;//是否显示删除图标public DragRecyclerViewAdapter(Context context, List<String> contentList) {this.context = context;this.contentList = contentList;}@NonNull@Overridepublic DragHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {View view = LayoutInflater.from(context).inflate(R.layout.item_drag_recyclerview, parent, false);return new DragHolder(view);}@Overridepublic void onBindViewHolder(@NonNull final DragHolder holder, int position) {if (isShowDelete){holder.img_delete.setVisibility(View.VISIBLE);if (position == 0){holder.img_delete.setVisibility(View.GONE);}}else {holder.img_delete.setVisibility(View.GONE);}holder.tv_content.setText(contentList.get(position));//删除holder.img_delete.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {onItemDissmiss(holder);}});}@Overridepublic int getItemCount() {return contentList.size();}@Overridepublic void onItemMove(RecyclerView.ViewHolder source, RecyclerView.ViewHolder target) {int fromPosition = source.getAdapterPosition();int toPosition = target.getAdapterPosition();if (fromPosition == 0 || toPosition == 0){//这个判断根据实际修改，可加可不加Toast.makeText(context,"第一个不可移动",Toast.LENGTH_SHORT).show();}else {if (fromPosition < contentList.size() && toPosition < contentList.size()) {//交换数据位置Collections.swap(contentList, fromPosition, toPosition);//刷新位置交换notifyItemMoved(fromPosition, toPosition);}//移动过程中移除view的放大效果onItemClear(source);}}@Overridepublic void onItemDissmiss(RecyclerView.ViewHolder source) {int position = source.getAdapterPosition();contentList.remove(position); //移除数据notifyItemRemoved(position);//刷新数据移除}@Overridepublic void onItemSelect(RecyclerView.ViewHolder source) {//当拖拽选中时放大选中的viewsource.itemView.setScaleX(1.2f);source.itemView.setScaleY(1.2f);}@Overridepublic void onItemClear(RecyclerView.ViewHolder source) {//拖拽结束后恢复view的状态source.itemView.setScaleX(1.0f);source.itemView.setScaleY(1.0f);}public class DragHolder extends RecyclerView.ViewHolder {private final TextView tv_content;private final ImageView img_delete;//删除图标public DragHolder(View itemView) {super(itemView);tv_content = itemView.findViewById(R.id.tv_content);img_delete = itemView.findViewById(R.id.img_delete);}}public void setContentList(Context context, List<String> contentList,boolean isShowDelete){this.context = context;this.contentList = contentList;this.isShowDelete = isShowDelete;notifyDataSetChanged();}
}4、item的布局文件 item_drag_recyclerview
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="@dimen/dimen_70dp"android:layout_height="@dimen/dimen_70dp"android:layout_margin="@dimen/dimen_10dp"><TextViewandroid:id="@+id/tv_content"android:layout_width="@dimen/dimen_60dp"android:layout_height="@dimen/dimen_60dp"android:text="1"android:textSize="@dimen/dimen_20dp"android:textColor="@color/text"android:textStyle="bold"android:gravity="center"android:background="@color/viewGray"android:layout_centerInParent="true"/><ImageViewandroid:id="@+id/img_delete"android:layout_width="@dimen/dimen_20dp"android:layout_height="@dimen/dimen_20dp"android:layout_alignParentRight="true"android:src="@mipmap/vibration_college_search_icon_empty"android:visibility="gone"/></RelativeLayout>5、最后就是在我们的页面Activity中使用了，这里虚拟设置了20个数字
setDragData();dragRecyclerView = findViewById(R.id.dragRecyclerView);//创建adapterdragRecyclerViewAdapter = new DragRecyclerViewAdapter(this, contentList);//设置默认的布局方式dragRecyclerView.setLayoutManager(new GridLayoutManager(this, 5,GridLayoutManager.VERTICAL, false));//设置adapterdragRecyclerView.setAdapter(dragRecyclerViewAdapter);//创建SimpleItemTouchHelperCallbackItemTouchHelper.Callback callback = new SimpleItemTouchHelperCallback(dragRecyclerViewAdapter);//用Callback构造ItemtouchHelperItemTouchHelper touchHelper = new ItemTouchHelper(callback);//调用ItemTouchHelper的attachToRecyclerView方法建立联系touchHelper.attachToRecyclerView(dragRecyclerView);//编辑tv_edit = findViewById(R.id.tv_edit);tv_edit.setOnClickListener(new View.OnClickListener() {@Overridepublic void onClick(View v) {if (tv_edit.getText().toString().equals("编辑")){tv_edit.setText("完成");dragRecyclerViewAdapter.setContentList(SetTextColorActivity.this,contentList,true);}else {tv_edit.setText("编辑");dragRecyclerViewAdapter.setContentList(SetTextColorActivity.this,contentList,false);}}});private void setDragData(){for (int i = 1; i < 21; i++){contentList.add(i+"");}}具体在项目中的实现需按实际需求来优化处理
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