Android RecyclerView(进阶篇)

作者 : 开心源码 本文共18267个字,预计阅读时间需要46分钟 发布时间: 2022-05-13 共223人阅读

进入进阶篇,相信大家通过之前的入门篇已经有了肯定的认识了,接下来就是我们通过RecyclerView实现少量自己的功能

可以先阅读Android RecyclerView(入门篇)

目录

  • 点击事件
  • 增加、删除数据
  • 更丰富的条目展现(多条目展现)
  • 增加header 、footer
  • 下拉刷新、上拉加载更多

进阶一:点击事件、长按事件(实现adapter和Activity之间的通信)

RecyclerView要实现点击事件和长按事件可以在适配器中定义接口事件回调

1、定义对象private OnItemClickListener mOnItemClickListener;2、写接口,并定义方法/*** 通过在adapter定义接口实现回调*/public interface OnItemClickListener {   //点击事件   void onItemClick(View view, int position);   //长按点击事件   void onItemLongClick(View view, int position);}3、public void setOnItemClickListener(OnItemClickListener mOnItemClickListener) {        this.mOnItemClickListener = mOnItemClickListener;}4、在adapter需要的地方调用事件if (mOnItemClickListener != null) {   mOnItemClickListener.onItemClick(((ContentViewHolder) holder).llLayout, position - 1);}if (mOnItemClickListener != null) {   mOnItemClickListener.onItemLongClick(((ContentViewHolder) holder).llLayout, position - 1);}5、Activity调用Adapter中的事件recyclerViewAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {            @Override            public void onItemClick(View view, int position) {                Toast.makeText(RecycleActivity.this, "点击了第" + position + "条", Toast.LENGTH_SHORT).show();            }            @Override            public void onItemLongClick(View view, int position) {                Toast.makeText(RecycleActivity.this, "长按了第" + position + "条", Toast.LENGTH_SHORT).show();            }});

点击事件、长按事件.gif

进阶二:增加数据、删除某条数据

这里需要理解到刷新界面的多种方式

        notifyDataSetChanged();//刷新整体布局        notifyItemChanged(position);//刷新指定position,会重新调用onBindViewHolder来进行刷新,假如当前position在屏幕之外,则不会调用,当重新滚动到屏幕内,会重新调用        notifyItemRangeChanged(position, 10);//刷新从position开始之后10条数据        notifyItemInserted(position);//在第position处插入数据,这个插入时会有动画        notifyItemMoved(position,5);//将当前position移动到position为5的地方,并且刷新        notifyItemRangeInserted(3,10);//批量添加        notifyItemRemoved(position);//删除第position条数据        notifyItemRangeRemoved(position, 10);//批量删除
/**     * 删除某条数据     *     * @param position     */    public void removeData(int position) {        mList.remove(position);        notifyItemRemoved(position);        notifyItemRangeChanged(position, mList.size());    }        /**         * 在指定position增加数据         *         * @param position         */        public void addData(int position, String msg) {            if (mList == null) {                mList = new ArrayList<>();            }            if (position < mList.size()) {                //说明这里是第一条                mList.add(position, msg);            } else {                mList.add(msg);                position = mList.size() - 1;            }            notifyItemInserted(position);            notifyItemRangeChanged(position, mList.size());        }
问题一:长按事件、点击事件同时发生

错误的增加、删除.gif

处理思路

在public boolean onLongClick(View v) {return true}
需要消费掉这个长按事件 返回true

正确的增加、删除.gif

进阶三:增加header、footer

思路
1、首先要区分头布局、中间布局、尾布局三种不同的type,通过设置一个int值来判断不同的布局2、通过getItemViewType来返回type3、在onCreateViewHolder中根据不同的viewType显示不同的布局4、在onBindViewHolder根据不同的holder加载不同的数据
注意

1、getItemCount这里需要返回的集合的数量+header数量+footer数量
2、当content布局中加载数据是通过position获取数据时需要将
position-1

1、增加三种不同的type来区分不同的布局
public static final int ITEM_TYPE_CONTENT = 0;public static final int ITEM_TYPE_FOOTER = 1;public static final int ITEM_TYPE_HEADER = 2;
2、增加头、尾布局数量
private int footerCount = 1;private int headerCount = 1;
3、根据position获取Item的类型
@Override    public int getItemViewType(int position) {        if (isHeaderView(position)) {            return ITEM_TYPE_HEADER;        } else if (isFooterView(position)) {            return ITEM_TYPE_FOOTER;        } else {            return ITEM_TYPE_CONTENT;        }    }
4、根据不同的viewType显示不同的布局
 @NonNull        @Override        public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {            /**             * 主要负责把加载子项的布局             * 将xml定义的布局实例化为view对象             */            if (viewType == ITEM_TYPE_FOOTER) {                View view = LayoutInflater.from(mContext).inflate(R.layout.recycler_footer_item, viewGroup, false);                return new FooterViewHolder(view);            } else if (viewType == ITEM_TYPE_HEADER) {                View view = LayoutInflater.from(mContext).inflate(R.layout.recycler_header_item, viewGroup, false);                return new HeaderViewHolder(view);            } else if (viewType == ITEM_TYPE_CONTENT) {                View view = LayoutInflater.from(mContext).inflate(R.layout.recyclerview_item, viewGroup, false);                return new ContentViewHolder(view);            }            return null;        }
5、根据不同的ViewHolder加载不同的数据(注意content中通过position加载数据position需要-1)
 @Override            public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {                //主要负责绑定数据                if (holder instanceof HeaderViewHolder) {                } else if (holder instanceof FooterViewHolder) {                } else if (holder instanceof ContentViewHolder) {                    ((ContentViewHolder) holder).tvItem.setText(mList.get(position - 1));                    ((ContentViewHolder) holder).llLayout.setOnClickListener(new View.OnClickListener() {                        @Override                        public void onClick(View v) {                            if (mOnItemClickListener != null) {                                mOnItemClickListener.onItemClick(((ContentViewHolder) holder).llLayout, position - 1);                            }                        }                    });                    ((ContentViewHolder) holder).llLayout.setOnLongClickListener(new View.OnLongClickListener() {                        @Override                        public boolean onLongClick(View v) {                            if (mOnItemClickListener != null) {                                mOnItemClickListener.onItemLongClick(((ContentViewHolder) holder).llLayout, position - 1);                            }                            return true;                        }                    });                }            }
6、返回的集合数量(务必加上header、footer)
@Override                public int getItemCount() {                    //返回集合的数量                    return mList.size() + headerCount + footerCount;                }
7、判断当前 item 能否是 FooterView
/**     * 判断当前 item 能否是 FooterView     */    public boolean isFooterView(int position) {        return footerCount != 0 && position >= (footerCount + mList.size());    }
8、判断当前 item 能否是 HeaderView
/**     * 判断当前 item 能否是 HeaderView     */    public boolean isHeaderView(int position) {        return headerCount != 0 && position < headerCount;    }
需加
class HeaderViewHolder extends RecyclerView.ViewHolder {                        public HeaderViewHolder(@NonNull View itemView) {                            super(itemView);                        }                    }                    class FooterViewHolder extends RecyclerView.ViewHolder {                            public FooterViewHolder(@NonNull View itemView) {                                super(itemView);                            }                        }

纵向增加头布局、尾布局.jpg

问题一

当我们为recyclerView设置表格布局时,设置footer、header,假如不做任何解决就会出现下方错误

错误增加表格布局头布局、尾布局.jpg

处理思路

1、通过setSpanSizeLookup重新设置显示的列数
2、通过判断当前view是footer、header,若是footer、header则占取整列,否则占取自己列

 @Override    public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) {        RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();        if (manager instanceof GridLayoutManager) {            //通过强转将manager转换成GridLayoutManager类型            final GridLayoutManager gridLayoutManager = (GridLayoutManager) manager;            //通过setSpanSizeLookup重新设置显示的列数            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {                @Override                public int getSpanSize(int position) {                    //通过判断当前view能否是footer、header                    //若是footer、header则占取整列,否则占取自己列                  return (isHeaderView(position) || isFooterView(position)) ? gridLayoutManager.getSpanCount() : 1;                }            });        }    }

表格布局正确增加头布局、尾部居.jpg

进阶四:下拉刷新、上拉加载更多

下拉刷新:在RecyclerView布局外层增加SwipeRefreshLayout
上拉加载更多:通过RecyclerView的addOnScrollListener来判断房前滚动的状态能否是最后一个Item,来进行加载更多

1、布局
<android.support.v4.widget.SwipeRefreshLayout            android:id="@+id/swipe_refresh_layout"            android:layout_width="match_parent"            android:layout_height="match_parent">        <android.support.v7.widget.RecyclerView                android:id="@+id/recycleview"                android:layout_width="match_parent"                android:layout_height="match_parent"/>    </android.support.v4.widget.SwipeRefreshLayout>
2、通过swipeRefreshLayout.setOnRefreshListener来进行下拉刷新
swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {            @Override            public void onRefresh() {                Handler handler = new Handler();                handler.postDelayed(new Runnable() {                    @Override                    public void run() {                        /**                         *要执行的操作                         */                        recyclerViewAdapter.addData(0, "我是刷新出来的数据");                        swipeRefreshLayout.setRefreshing(false);                        Toast.makeText(RecycleActivity.this, "下拉刷新成功", Toast.LENGTH_SHORT).show();                    }                }, 1500);//3秒后执行Runnable中的run方法            }        });
3、通过调用addOnScrollListener来进行加载更多

onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState)//滚动状态变化时的回调
onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy)//滚动时回调

mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {            /**             *             * @param recyclerView 当前滚动的recyclerView             * @param newState 当前滚动的状态             *             *  public static final int SCROLL_STATE_IDLE = 0;静止没有滚动             *  public static final int SCROLL_STATE_DRAGGING = 1;正在被外部拖拽,即可使用户滑动             *  public static final int SCROLL_STATE_SETTLING = 2;//自动滚动             *             *             */            @Override            public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {                //滚动状态变化时的回调                super.onScrollStateChanged(recyclerView, newState);                //先判断当前状态能否已中止                //判断最后一条数据+1能否是集合的数据                //判断能否滑动到最底部                if (newState == RecyclerView.SCROLL_STATE_IDLE && (lastVisibleItem + 1 == recyclerViewAdapter.getItemCount())) {                    //判断总数>0 说明可以加载更多                    if (total > 0) {                        //判断total > count 说明还可以加载数据                        if (total > count) {                            Toast.makeText(RecycleActivity.this, "上拉加载", Toast.LENGTH_SHORT).show();                            count += 10;//每次加载10条                            getData();//加载的数据                            recyclerViewAdapter.notifyDataSetChanged();//刷新适配器                        } else {                            Toast.makeText(RecycleActivity.this, "没有数据加载了", Toast.LENGTH_SHORT).show();                        }                    } else {                        Toast.makeText(RecycleActivity.this, "没有数据加载了", Toast.LENGTH_SHORT).show();                    }                }            }            /**             *             * @param recyclerView 当前滚动的recyclerView             * @param dx 水平滚动距离             *           dx > 0 时为手指向左滚动,列表滚动显示右面的内容             *           dx < 0 时为手指向右滚动,列表滚动显示左面的内容             * @param dy 垂直滚动距离             *           dy > 0 时为手指向上滚动,列表滚动显示下面的内容             *           dy < 0 时为手指向下滚动,列表滚动显示上面的内容             */            @Override            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {                super.onScrolled(recyclerView, dx, dy);                //滚动时回调                //最后一个可见Item                lastVisibleItem = mLinearLayoutManager.findLastVisibleItemPosition();            }        });

下拉刷新、上拉加载更多.gif

整体代码

为了更好的方便查,我把Activity和Adapter放在一起写,开发中大家肯定要分开逻辑来操作

package com.example.androidhightproject.module;import android.content.Context;import android.graphics.Rect;import android.os.Bundle;import android.os.Handler;import android.support.annotation.NonNull;import android.support.v4.widget.SwipeRefreshLayout;import android.support.v7.app.AppCompatActivity;import android.support.v7.widget.*;import android.util.Log;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.LinearLayout;import android.widget.TextView;import android.widget.Toast;import com.example.androidhightproject.R;import java.util.ArrayList;import java.util.List;/** * @author dongbo */public class RecycleActivity extends AppCompatActivity {    private List<String> mList = new ArrayList<>();    private RecyclerView mRecyclerView;    private SwipeRefreshLayout swipeRefreshLayout;    private int lastVisibleItem;    private int total = 30;    private int count = 10;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_recycle);        mRecyclerView = (RecyclerView) findViewById(R.id.recycleview);        swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipe_refresh_layout);        /**         * 设置布局管理器         * 默认垂直排布  LinearLayoutManager.VERTICAL垂直  LinearLayoutManager.HORIZONTAL水平         * boolean reverseLayout 默认是false 能否反转         *         */        LinearLayoutManager mLinearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);        mRecyclerView.setLayoutManager(mLinearLayoutManager);        //设置纵向默认排列//        mRecyclerView.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false));        //设置横向默认排列,这里需要注意改成横向列表,分割线需要改成横向//        mRecyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.HORIZONTAL,false));        //设置表格布局,这里需要注意的是,有很多需求是根据返回的数据显示表格的数量,所以分割线需要自己重新定义//        mRecyclerView.setLayoutManager(new GridLayoutManager(this, 3));        //设置瀑布流显示//        mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL));        //默认的分割线        mRecyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));        //设置自己设置分割线//        mRecyclerView.addItemDecoration(new SpaceItemDecoation(3));        //设置删除时的动画        mRecyclerView.setItemAnimator(new DefaultItemAnimator());        RecyclerViewAdapter recyclerViewAdapter = new RecyclerViewAdapter(getData(), this);        mRecyclerView.setAdapter(recyclerViewAdapter);        swipeRefreshLayout.setColorSchemeResources(R.color.colorAccent);        swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {            @Override            public void onRefresh() {                Handler handler = new Handler();                handler.postDelayed(new Runnable() {                    @Override                    public void run() {                        /**                         *要执行的操作                         */                        recyclerViewAdapter.addData(0, "我是刷新出来的数据");                        swipeRefreshLayout.setRefreshing(false);                        Toast.makeText(RecycleActivity.this, "下拉刷新成功", Toast.LENGTH_SHORT).show();                    }                }, 1500);//3秒后执行Runnable中的run方法            }        });        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {            /**             *             * @param recyclerView 当前滚动的recyclerView             * @param newState 当前滚动的状态             *             *  public static final int SCROLL_STATE_IDLE = 0;静止没有滚动             *  public static final int SCROLL_STATE_DRAGGING = 1;正在被外部拖拽,即可使用户滑动             *  public static final int SCROLL_STATE_SETTLING = 2;//自动滚动             *             *             */            @Override            public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {                //滚动状态变化时的回调                super.onScrollStateChanged(recyclerView, newState);                //先判断当前状态能否已中止                //判断最后一条数据+1能否是集合的数据                //判断能否滑动到最底部                Log.e("newState", newState + "");                if (newState == RecyclerView.SCROLL_STATE_IDLE && (lastVisibleItem + 1 == recyclerViewAdapter.getItemCount())) {                    //判断总数>0 说明可以加载更多                    if (total > 0) {                        //判断total > count 说明还可以加载数据                        if (total > count) {                            Toast.makeText(RecycleActivity.this, "上拉加载", Toast.LENGTH_SHORT).show();                            count += 10;//每次加载10条                            getData();//加载的数据                            recyclerViewAdapter.notifyDataSetChanged();//刷新适配器                        } else {                            Toast.makeText(RecycleActivity.this, "没有数据加载了", Toast.LENGTH_SHORT).show();                        }                    } else {                        Toast.makeText(RecycleActivity.this, "没有数据加载了", Toast.LENGTH_SHORT).show();                    }                }            }            /**             *             * @param recyclerView 当前滚动的recyclerView             * @param dx 水平滚动距离             *           dx > 0 时为手指向左滚动,列表滚动显示右面的内容             *           dx < 0 时为手指向右滚动,列表滚动显示左面的内容             * @param dy 垂直滚动距离             *           dy > 0 时为手指向上滚动,列表滚动显示下面的内容             *           dy < 0 时为手指向下滚动,列表滚动显示上面的内容             */            @Override            public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {                super.onScrolled(recyclerView, dx, dy);                //滚动时回调                //最后一个可见Item                Log.e("dx", dx + "");                lastVisibleItem = mLinearLayoutManager.findLastVisibleItemPosition();            }        });        recyclerViewAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {            @Override            public void onItemClick(View view, int position) {                Toast.makeText(RecycleActivity.this, "点击了第" + position + "条", Toast.LENGTH_SHORT).show();                recyclerViewAdapter.addData(position, "我是增加的数据");            }            @Override            public void onItemLongClick(View view, int position) {                Toast.makeText(RecycleActivity.this, "长按了第" + position + "条", Toast.LENGTH_SHORT).show();                recyclerViewAdapter.removeData(position);            }        });    }    private List<String> getData() {        for (int i = 0; i < 10; i++) {            mList.add("测试数据" + i);//            mList.add("照片地址");        }        return mList;    }}class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerView.ViewHolder> {    /**     * 首先要区分头布局、中间布局、尾布局三种不同的type,通过设置一个int值来判断不同的布局     * 通过getItemViewType来返回type     * 在onCreateViewHolder中根据不同的viewType显示不同的布局     * 在onBindViewHolder根据不同的holder加载不同的数据     * 注意:     * 1、getItemCount这里需要返回的集合的数量+header数量+footer数量     * 2、当content布局中加载数据是通过position获取数据时需要将position-1     */    private List<String> mList;    private Context mContext;    private OnItemClickListener mOnItemClickListener;    public static final int ITEM_TYPE_CONTENT = 0;    public static final int ITEM_TYPE_FOOTER = 1;    public static final int ITEM_TYPE_HEADER = 2;    private int footerCount = 1;    private int headerCount = 1;    public RecyclerViewAdapter(List<String> mList, Context mContext) {        //大部分只有数据与上下文        this.mList = mList;        this.mContext = mContext;    }    public void setOnItemClickListener(OnItemClickListener mOnItemClickListener) {        this.mOnItemClickListener = mOnItemClickListener;    }    /**     * 删除某条数据     *     * @param position     */    public void removeData(int position) {        notifyItemRemoved(position);        mList.remove(position);        notifyItemRangeChanged(position, mList.size());    }    /**     * 在指定position增加数据     *     * @param position     */    public void addData(int position, String msg) {        notifyItemInserted(position);        if (mList == null) {            mList = new ArrayList<>();        }        if (position < mList.size()) {            //说明这里是第一条            mList.add(position, msg);        } else {            mList.add(msg);            position = mList.size() - 1;        }        notifyItemRangeChanged(position, mList.size());    }    @Override    public int getItemViewType(int position) {        if (isHeaderView(position)) {            return ITEM_TYPE_HEADER;        } else if (isFooterView(position)) {            return ITEM_TYPE_FOOTER;        } else {            return ITEM_TYPE_CONTENT;        }    }    @Override    public void onAttachedToRecyclerView(@NonNull RecyclerView recyclerView) {        RecyclerView.LayoutManager manager = recyclerView.getLayoutManager();        if (manager instanceof GridLayoutManager) {            //通过强转将manager转换成GridLayoutManager类型            final GridLayoutManager gridLayoutManager = (GridLayoutManager) manager;            //通过setSpanSizeLookup重新设置显示的列数            gridLayoutManager.setSpanSizeLookup(new GridLayoutManager.SpanSizeLookup() {                @Override                public int getSpanSize(int position) {                    //通过判断当前view能否是footer、header                    //若是footer、header则占取整列,否则占取自己列                    return (isHeaderView(position) || isFooterView(position)) ? gridLayoutManager.getSpanCount() : 1;                }            });        }    }    @NonNull    @Override    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int viewType) {        /**         * 主要负责把加载子项的布局         * 将xml定义的布局实例化为view对象         */        if (viewType == ITEM_TYPE_FOOTER) {            View view = LayoutInflater.from(mContext).inflate(R.layout.recycler_footer_item, viewGroup, false);            return new FooterViewHolder(view);        } else if (viewType == ITEM_TYPE_HEADER) {            View view = LayoutInflater.from(mContext).inflate(R.layout.recycler_header_item, viewGroup, false);            return new HeaderViewHolder(view);        } else if (viewType == ITEM_TYPE_CONTENT) {            View view = LayoutInflater.from(mContext).inflate(R.layout.recyclerview_item, viewGroup, false);            return new ContentViewHolder(view);        }        return null;    }    @Override    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {        //主要负责绑定数据        if (holder instanceof HeaderViewHolder) {        } else if (holder instanceof FooterViewHolder) {        } else if (holder instanceof ContentViewHolder) {//            Glide.with(mContext).load(mList.get(position-1)).into(((ContentViewHolder) holder).ivImage);            ((ContentViewHolder) holder).tvItem.setText(mList.get(position - 1));            ((ContentViewHolder) holder).llLayout.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View v) {                    if (mOnItemClickListener != null) {                        mOnItemClickListener.onItemClick(((ContentViewHolder) holder).llLayout, position - 1);                    }                }            });            ((ContentViewHolder) holder).llLayout.setOnLongClickListener(new View.OnLongClickListener() {                @Override                public boolean onLongClick(View v) {                    if (mOnItemClickListener != null) {                        mOnItemClickListener.onItemLongClick(((ContentViewHolder) holder).llLayout, position - 1);                    }                    return true;                }            });        }    }    @Override    public int getItemCount() {        //返回集合的数量        return mList.size() + headerCount + footerCount;    }    class HeaderViewHolder extends RecyclerView.ViewHolder {        public HeaderViewHolder(@NonNull View itemView) {            super(itemView);        }    }    class FooterViewHolder extends RecyclerView.ViewHolder {        public FooterViewHolder(@NonNull View itemView) {            super(itemView);        }    }    class ContentViewHolder extends RecyclerView.ViewHolder {//        private final ImageView ivImage;        private final TextView tvItem;        private final LinearLayout llLayout;        public ContentViewHolder(@NonNull View itemView) {            super(itemView);            tvItem = (TextView) itemView.findViewById(R.id.tv_item);            llLayout = (LinearLayout) itemView.findViewById(R.id.ll_layout);//            ivImage = (ImageView) itemView.findViewById(R.id.iv_image);        }    }    /**     * 通过在adapter定义接口实现回调     */    public interface OnItemClickListener {        //点击事件        void onItemClick(View view, int position);        //长按点击事件        void onItemLongClick(View view, int position);    }    /**     * 判断当前 item 能否是 FooterView     */    public boolean isFooterView(int position) {        return footerCount != 0 && position >= (footerCount + mList.size());    }    /**     * 判断当前 item 能否是 HeaderView     */    public boolean isHeaderView(int position) {        return headerCount != 0 && position < headerCount;    }}class SpaceItemDecoation extends RecyclerView.ItemDecoration {    private int space;    public SpaceItemDecoation(int space) {        this.space = space;    }    @Override    public void getItemOffsets(@NonNull Rect outRect, @NonNull View view, @NonNull RecyclerView parent, @NonNull RecyclerView.State state) {        super.getItemOffsets(outRect, view, parent, state);        //假如不是第一个盒子设置一个居左和居下的边距        outRect.left = space;        outRect.bottom = space;        //大部分的需求都是3个 由于第一个都是你设置个数的倍数,所以通过取余来将左边距设置为0        if (parent.getChildLayoutPosition(view) % 3 == 0) {            outRect.left = 0;        }    }}

最后

到此对于RecyclerView你已经可以实现项目中的使用,还有很多需要我们来探究,比方回收复用机制、缓存机制等等,我也正在学习~
喜欢记得点赞或者者关注我哦, 有意见或者者建议评论区见~

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开心源码网 » Android RecyclerView(进阶篇)

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