Android使用ItemTouchHelper实现RecyclerView的item拖动位置交换

Posted 2022-06-29 Mars-xq

demo：

import android.graphics.Color;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.GridLayoutManager;
import androidx.recyclerview.widget.ItemTouchHelper;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

public class MainActivity5 extends AppCompatActivity 

    private final List<String> mData = new ArrayList<>();

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) 
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main5);

        RecyclerView recyclerView = findViewById(R.id.recyclerView);

        for (int i = 0; i < 200; i++) 
            mData.add("source" + i);
        

        RvAdapter rvAdapter = new RvAdapter(mData);
        recyclerView.setAdapter(rvAdapter);
        recyclerView.setLayoutManager(new GridLayoutManager(this, 8));

        MyItemTouchHelper myItemTouchHelper = new MyItemTouchHelper(mData);
        ItemTouchHelper itemTouchHelper = new ItemTouchHelper(myItemTouchHelper);
        itemTouchHelper.attachToRecyclerView(recyclerView);
    


    /**
     * 处理RecycleView的选中,拖拽移动,拖拽删除的实现类
     */
    public static class MyItemTouchHelper extends ItemTouchHelper.Callback 

        private final List<String> mData;

        public MyItemTouchHelper(List<String> mData) 
            this.mData = mData;
        

        @Override
        public int getMovementFlags(RecyclerView recyclerView,
                                    @NonNull RecyclerView.ViewHolder viewHolder) 

            int dragFlags;
            if (recyclerView.getLayoutManager() instanceof GridLayoutManager) 
                dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN |
                        ItemTouchHelper.LEFT | ItemTouchHelper.RIGHT;
             else 
                dragFlags = ItemTouchHelper.UP | ItemTouchHelper.DOWN;
            
            int swipeFlags = 0;
            return makeMovementFlags(dragFlags, swipeFlags);
        

        @Override
        public boolean isLongPressDragEnabled() 
            return true;  //长按启用拖拽
        

        @Override
        public boolean isItemViewSwipeEnabled() 
            return false; //不启用拖拽删除
        

        @Override
        public boolean onMove(@NonNull RecyclerView recyclerView,
                              @NonNull RecyclerView.ViewHolder source,
                              @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ViewHolder
            int fromPosition = source.getAdapterPosition();
            int toPosition = target.getAdapterPosition();
            if (fromPosition < mData.size() && toPosition < mData.size()) 
                //交换数据位置
                Collections.swap(mData, fromPosition, toPosition);
                //刷新位置交换
                RvAdapter adapter = (RvAdapter) recyclerView.getAdapter();
                if (adapter != null) 
                    adapter.notifyItemMoved(fromPosition, toPosition);
                
            
            return true;
        

        @Override
        public void onSwiped(@NonNull RecyclerView.ViewHolder viewHolder, int direction) 
            //移动删除回调,如果不用可以不用理
        

        @Override
        public void onSelectedChanged(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ViewHolder
                //当拖拽选中时放大选中的view
                viewHolder.itemView.setScaleX(1.2f);
                viewHolder.itemView.setScaleY(1.2f);
                viewHolder.itemView.setBackgroundColor(Color.RED);
            
        

        @Override
        public 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ViewHolder
                viewHolder.itemView.setScaleX(1.0f);
                viewHolder.itemView.setScaleY(1.0f);
                viewHolder.itemView.setBackgroundColor(Color.BLUE);
            
        
    

    public static class RvAdapter extends RecyclerView.Adapter<RvAdapter.VHolder> 

        private final List<String> mData;

        public RvAdapter(List<String> mData) 
            this.mData = mData;
        

        @NonNull
        @Override
        public VHolder onCreateViewHolder(ViewGroup parent, int viewType) 
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.item_rv, parent, false);
            return new VHolder(view);
        

        @Override
        public void onBindViewHolder(RvAdapter.VHolder holder, int position) 
            holder.mTextView1.setText(mData.get(position));
            holder.mTextView2.setText(String.valueOf(position));
        

        @Override
        public int getItemCount() 
            return mData.size();
        

        public static class VHolder extends RecyclerView.ViewHolder 

            private final TextView mTextView1;
            private final TextView mTextView2;

            public VHolder(View itemView) 
                super(itemView);

                mTextView1 = (TextView) itemView.findViewById(R.id.tv1);
                mTextView2 = (TextView) itemView.findViewById(R.id.tv2);
            
        
    

activity_main5.xml：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:itemCount="50"
        tools:listitem="@layout/item_rv" />

</LinearLayout>

item_rv.xml :

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="80dp"
    android:layout_margin="10dp"
    android:background="@android:color/holo_blue_dark"
    android:gravity="center"
    android:orientation="vertical">

    <TextView
        android:id="@+id/tv1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:textColor="@android:color/white"
        android:textSize="18sp"
        tools:text="@tools:sample/cities" />

    <TextView
        android:id="@+id/tv2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text=""
        android:textColor="@android:color/white"
        android:textSize="14sp"
        tools:text="@tools:sample/cities" />

</LinearLayout>