RecyclerView具体解释-白红宇

RecyclerView具体解释

阅读量：6599 次

发布时间：2019-06-24

本文共 8022 字，大约阅读时间需要 26 分钟。

public class RecyclerView extends ViewGroup implements ScrollingView, NestedScrollingChild {

由上面的继承结构，我们easy看出，RecyclerView实际上也是一个ViewGroup继承了ScrollingView和NestedScrolling，方便实现横向与纵向滑动。

RecyclerView是support-v7包中的新组件，是一个强大的滑动组件。与经典的ListView相比，相同拥有item回收复用的功能，可是直接把viewholder的实现封装起来。用户仅仅要实现自己的viewholder就能够了。该组件会自己主动帮你回收复用每个item。

RecyclerView的长处：

1.它不关心item是否显示的位置与方式 ---> layoutManager 我们能够只使用layoutManager一句话就能够切换RecyclerView的样式

2.它不关心item怎样切割 --->ItemDecoration 我们能够依据自己项目的须要自己定义自己的切割线

3.它不关心item添加与删除动画的效果 --->ItemAnimator 我们能够依据自己的须要定义item的添加与删除动画

4.只关心怎样服用view --->ViewHolder google强制我们使用viewHolder，我们须要自定义自己的ViewHolder哦。

RecyclerView的缺点：

1.内部没有实现对单个Item点击事件的监听，须要自定义item的单击和长按事件。

2.对item添加后的position測量不准确，须要在adapter中使用holer.getLayoutPosition()方法获取。

由上我们不难看出，RecyclerView的长处远远大于它的缺点啊，再说它的缺点也不算缺点啊，都有非常好的解决的方法。那么我们还有什么理由不是哟只是它呢？

SO，我们開始吧。

首先，我们须要引入官方提供的向下兼容的V7包，详细引入方法，这里不再赘述。

下一步在xml文件里引入 RecyclerView。

MainActivity

package com.flyou.henucenter.recycterview;import android.os.Bundle;import android.support.v7.app.AppCompatActivity;import android.support.v7.widget.DefaultItemAnimator;import android.support.v7.widget.GridLayoutManager;import android.support.v7.widget.LinearLayoutManager;import android.support.v7.widget.RecyclerView;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.Toast;import com.flyou.henucenter.recycterview.adpater.RecyclerViewAdapter;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity {    private RecyclerViewAdapter recyclerViewAdapter;    private List
     
       datas;    private RecyclerView recyclerview;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        initdate();        initView();    }    private void initdate() {        datas = new ArrayList<>();        for (int i = 'A'; i < 'z'; i++) {            datas.add((char) i + "");        }    }    @Override    public boolean onCreateOptionsMenu(Menu menu) {        // Inflate the menu; this adds items to the action bar if it is present.        getMenuInflater().inflate(R.menu.menu_main, menu);        return true;    }    @Override    public boolean onOptionsItemSelected(MenuItem item) {        int id = item.getItemId();        switch (id) {            //Gridview             case R.id.action_Gridview:                GridLayoutManager gridLayoutManager = new GridLayoutManager(this, 4, GridLayoutManager.VERTICAL, false);                recyclerview.setLayoutManager(gridLayoutManager);                break;            case R.id.action_Listview:                LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);                recyclerview.setLayoutManager(linearLayoutManager);                break;            case R.id.action_hor_GridView:                GridLayoutManager hor_gridLayoutManager = new GridLayoutManager(this, 4, GridLayoutManager.HORIZONTAL, false);                recyclerview.setLayoutManager(hor_gridLayoutManager);                break;            case R.id.action_pubu:                break;            case R.id.action_add:                recyclerViewAdapter.add(1);                break;            case R.id.action_delete:                recyclerViewAdapter.delete(1);                break;        }        return super.onOptionsItemSelected(item);    }    private void initView() {        recyclerview = (RecyclerView) findViewById(R.id.recyclerview);        RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(this, LinearLayoutManager.VERTICAL, false);        recyclerview.setLayoutManager(layoutManager);//        recyclerview.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL_LIST));        recyclerview.setItemAnimator(new DefaultItemAnimator());        recyclerViewAdapter = new RecyclerViewAdapter(datas, this);        recyclerview.setAdapter(recyclerViewAdapter);        recyclerViewAdapter.setOnItemClickListener(new RecyclerViewAdapter.OnItemClickListener() {            @Override            public void onItemClick(View view, int Position) {                Toast.makeText(MainActivity.this, "itemClick" + Position, Toast.LENGTH_SHORT).show();            }            @Override            public void onItemLongClick(View view, int Position) {                Toast.makeText(MainActivity.this, "ItemLongClick" + Position, Toast.LENGTH_SHORT).show();            }        });    }}

Adapter文件

package com.flyou.henucenter.recycterview.adpater;import android.content.Context;import android.support.v7.widget.RecyclerView;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.TextView;import com.flyou.henucenter.recycterview.R;import java.util.List;/** * 项目名称:My Application * * 包名:com.flyou.henucenter.myapplication.adpater * 作者: flyou * 创建时间:15/8/19 11:42 * 描写叙述: */public class RecyclerViewAdapter extends RecyclerView.Adapter
     
       {    private List
      
        mDatas;    private Context mContex;    private LayoutInflater mInFlater;//设置item的回调    public interface OnItemClickListener {        void onItemClick(View view, int Position);        void onItemLongClick(View view, int Position);    }    private OnItemClickListener onItemClickListener;    public void setOnItemClickListener(OnItemClickListener listener) {        this.onItemClickListener = listener;    }    public RecyclerViewAdapter(List
       
         datas, Context Contex) {        this.mContex = Contex;        this.mDatas = datas;        mInFlater = LayoutInflater.from(mContex);    }    @Override    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {        View view = mInFlater.inflate(R.layout.item_view, parent, false);        MyViewHolder viewHolder = new MyViewHolder(view);        return viewHolder;    }    public void add(int pos) {        mDatas.add(pos, "I am new item ");        notifyItemInserted(pos);    }    public void delete(int pos) {        mDatas.remove(pos);        notifyItemRemoved(pos);    }    @Override    public void onBindViewHolder(final MyViewHolder holder, final int position) {        holder.textView.setText(mDatas.get(position));        if (onItemClickListener != null) {            holder.itemView.setOnClickListener(new View.OnClickListener() {                @Override                public void onClick(View v) {                    int layoutPosition = holder.getLayoutPosition();                    onItemClickListener.onItemClick(holder.itemView,layoutPosition);                }            });            holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {                @Override                public boolean onLongClick(View v) {                    int layoutPosition = holder.getLayoutPosition();//添加或删除item使用这种方法获得其position                    onItemClickListener.onItemLongClick(holder.itemView,layoutPosition);                    return false;                }            });        }    }    @Override    public int getItemCount() {        return mDatas.size();    }}class MyViewHolder extends RecyclerView.ViewHolder {    TextView textView;    public MyViewHolder(View itemView) {        super(itemView);        textView = (TextView) itemView.findViewById(R.id.textInfo);    }}

单个Item

menu文件

//设置回调接口。方便在调用出进行处理。

public interface OnItemClickListener {        void onItemClick(View view, int Position);        void onItemLongClick(View view, int Position);    }    private OnItemClickListener onItemClickListener;    public void setOnItemClickListener(OnItemClickListener listener) {        this.onItemClickListener = listener;    }

没有录制gif大家凑合着看效果。

当然，item的添加和删除是有动画的，大家也能够在github上全部相关的动画库进行使用

https://github.com/gabrielemariotti/RecyclerViewItemAnimators

上面给出当中一个比較出色的RecylerView库。

大家也能够依据自己的须要自行定制，ok就先介绍到这里。

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