RecyclerView具体解释

阅读原文时间：2023年07月14日阅读：1

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。

<android.support.v7.widget.RecyclerView  
    android:id="@+id/recyclerview"  
    android:layout\_width="match\_parent"  
    android:layout\_height="match\_parent"  
     />

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<String> 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

<item  
    android:id="@+id/action\_Listview"  
    android:orderInCategory="100"  
    android:title="listview"  
    app:showAsAction="never" />  
<item  
    android:id="@+id/action\_Gridview"  
    android:orderInCategory="100"  
    android:title="gridView"  
    app:showAsAction="never" />  
<item  
    android:id="@+id/action\_hor\_GridView"  
    android:orderInCategory="100"  
    android:title="hor\_GridView"  
    app:showAsAction="never" />  
<item  
    android:id="@+id/action\_pubu"  
    android:orderInCategory="100"  
    android:title="pubuliu"  
    app:showAsAction="never" />  
<item  
    android:id="@+id/action\_add"  
    android:orderInCategory="100"  
    android:icon="@drawable/ic\_menu\_add"  
    android:title="add"  
    app:showAsAction="always" />  
<item  
    android:id="@+id/action\_delete"  
    android:orderInCategory="100"  
    android:icon="@drawable/ic\_menu\_delete"  
    android:title="delete"  
    app:showAsAction="always" />

//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;  
}