【Recycleview滑动】Recycleview+snapHelper实现列表联动

• 一篇小文章

直接上图
主要实现方法：
1）上方卡片滑动监听处理代码：

    mRecycleview.addonScrollListener(new RecyclerView.onScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);

				//recycleView中获取显示item的位置
                RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) recyclerView.getChildAt(0).getLayoutParams();
                int viewAdapterPosition = layoutParams.getViewAdapterPosition();
                //根据当前位置设置下方recycleView的位置
                recycleviewHint.smoothScrollToPosition(viewAdapterPosition);
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
            }
        });

下方列表点击事件处理：

        hintAdapter.setonItemClickListener(new baseQuickAdapter.onItemClickListener() {
            @Override
            public void onItemClick(baseQuickAdapter baseQuickAdapter, View view, int i) {
                mRecycleview.scrollToPosition(i);
                recycleviewHint.smoothScrollToPosition(i);
            }
        });

点击下方列表，当前item显示在中间关键代码需要改造LinearLayoutManager
感谢电动小马达的分享[RecyclerView 列表点击定位到中间位置]sn(https://blog.csdn.net/weixin_42046829/article/details/110053790)

public class CenterLayoutManager extends LinearLayoutManager {

    public CenterLayoutManager(Context context) {
        super(context);
    }

    public CenterLayoutManager(Context context, int orientation, boolean reverseLayout) {
        super(context, orientation, reverseLayout);
    }

    public CenterLayoutManager(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    public void smoothScrollToPosition(RecyclerView recyclerView, RecyclerView.State state, int position) {
        LinearSmoothScroller smoothScroller =
                new CenterSmoothScroller(recyclerView.getContext()) {
                    // 返回：滑过1px时经历的时间(ms)。
                    @Override
                    protected float calculateSpeedPerPixel(DisplayMetrics displayMetrics) {
                        return 150f / displayMetrics.densityDpi;
                    }
                };

        smoothScroller.setTargetPosition(position);
        startSmoothScroll(smoothScroller);
    }


    private static class CenterSmoothScroller extends LinearSmoothScroller {

        CenterSmoothScroller(Context context) {
            super(context);
        }

        @Override
        public int calculateDtToFit(int viewStart, int viewEnd, int boxStart, int boxEnd, int snapPreference) {
            return (boxStart + (boxEnd - boxStart) / 2) - (viewStart + (viewEnd - viewStart) / 2);
        }
    }
}

布局代码activity_main.xml

// An highlighted block



    

    

        

        

        
    

item.xml

item_rv_hint.xml

MenuActivity.class

import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.graphics.Palette;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.PagerSnapHelper;
import android.support.v7.widget.RecyclerView;
import android.view.View;
import android.widget.ImageView;
import android.widget.TextView;
import com.chad.library.adapter.base.baseQuickAdapter;
import com.chad.library.adapter.base.baseViewHolder;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private RecyclerView mRecycleview;
    private baseQuickAdapter mbaseQuickAdapter;
    private baseQuickAdapter hintAdapter;
    private ArrayList mDatas;
    private RecyclerView recycleviewHint;
    private ArrayList hintDatas = new ArrayList<>();
    private int[] imgs = {R.mipmap.a1, R.mipmap.a2, R.mipmap.a3, R.mipmap.a4, R.mipmap.a5, R.mipmap.a6, R.mipmap.a1, R.mipmap.a2, R.mipmap.a3, R.mipmap.a4, R.mipmap.a5, R.mipmap.a6};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mRecycleview = (RecyclerView) findViewById(R.id.recycleview);
        recycleviewHint = (RecyclerView) findViewById(R.id.recycleviewHint);
        final TextView tvHead = (TextView) findViewById(R.id.tvHead);
        final TextView tvFoot = (TextView) findViewById(R.id.tvFoot);
        final LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        linearLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        mRecycleview.setLayoutManager(linearLayoutManager);
        PagerSnapHelper snapHelper = new PagerSnapHelper();
        snapHelper.attachToRecyclerView(mRecycleview);
        mDatas = new ArrayList<>();
        for (int x = 0; x < imgs.length; x++) {
            TestBean testBean = new TestBean();
            testBean.setText("this is No." + (x + 1));
            testBean.setImgs(imgs[x]);
            mDatas.add(testBean);
            hintDatas.add(new TestBean((x + 1) + ""));
        }

        mbaseQuickAdapter = new baseQuickAdapter(R.layout.item, mDatas) {
            @Override
            protected void convert(baseViewHolder helper, TestBean item) {
                ImageView img = helper.getView(R.id.img);
                final TextView tv = helper.getView(R.id.tv);
                img.setImageResource(item.getImgs());
                tv.setText(item.getText());
                Palette.from(BitmapFactory.decodeResource(getResources(), item.getImgs())).generate(new Palette.PaletteAsyncListener() {
                    @Override
                    public void onGenerated(Palette palette) {
                        int vibrantColor = palette.getVibrantColor(Color.BLUE);
                        tv.setTextColor(vibrantColor);
                    }
                });
            }
        };
        mRecycleview.setAdapter(mbaseQuickAdapter);
        mRecycleview.addOnScrollListener(new RecyclerView.OnScrollListener() {
            @Override
            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                super.onScrollStateChanged(recyclerView, newState);

                RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) recyclerView.getChildAt(0).getLayoutParams();
                int viewAdapterPosition = layoutParams.getViewAdapterPosition();
                recycleviewHint.smoothScrollToPosition(viewAdapterPosition);
            }

            @Override
            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                super.onScrolled(recyclerView, dx, dy);
            }
        });

        final LinearLayoutManager centerLayoutManager = new CenterLayoutManager(this);
        centerLayoutManager.setOrientation(LinearLayoutManager.HORIZONTAL);
        hintAdapter = new baseQuickAdapter(R.layout.item_rv_hint, hintDatas) {
            @Override
            protected void convert(baseViewHolder helper, TestBean item) {
                final TextView tv = helper.getView(R.id.tv);
                tv.setText(item.getText());
            }
        };
        recycleviewHint.setLayoutManager(centerLayoutManager);
        recycleviewHint.setAdapter(hintAdapter);

        hintAdapter.setOnItemClickListener(new baseQuickAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(baseQuickAdapter baseQuickAdapter, View view, int i) {
                mRecycleview.scrollToPosition(i);
                recycleviewHint.smoothScrollToPosition(i);
            }
        });
        tvHead.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mRecycleview.scrollToPosition(0);
                recycleviewHint.scrollToPosition(0);
            }
        });
        tvFoot.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                mRecycleview.scrollToPosition(mDatas.size() - 1);
                recycleviewHint.scrollToPosition(hintDatas.size() - 1);
            }
        });
    }
}