RecyclerView详解

public class RecyclerView extends ViewGroup implements ScrollingView, NestedScrollingChild {}

由上面的继承结构,我们容易看出, 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,同样拥有item回收复用的功能,但是直接把viewholder的实现封装起来,用户只要实现自己的viewholder就可以了,该组件会自动帮你回收复用每一个item。

RecyclerView的优点:

1.它不关心item是否显示的位置与方式---> layoutManager 我们可以仅仅使用layoutManager一句话就可以切换RecyclerView的样式

2.它不关心item如何分割--->ItemDecoration 我们可以根据自己项目的需要自定义自己的分割线

3.它不关心item增加与删除动画的效果--->ItemAnimator我们可以根据自己的需要定义item的增加与删除动画

4.仅仅关心如何服用view--->ViewHolder google强制我们使用viewHolder,我们需要自己定义自己的ViewHolder哦。

RecyclerView的缺点:

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

2.对item增加后的position测量不准确,需要在adapter中使用holer.getLayoutPosition()方法获取。

由上我们不难看出,RecyclerView的优点远远大于它的缺点啊,再说它的缺点也不算缺点啊,都有很好的解决办法,那么我们还有什么理由不是哟不过它呢?

SO,我们开始吧。首先,我们需要引入官方提供的向下兼容的V7包,具体引入方法,这里不再赘述。

下一步在xml文件中引入 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();//增加或删除item使用这个方法获得其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的增加和删除是有动画的,大家也可以在github上所有相关的动画库进行使用
https://github.com/gabrielemariotti/RecyclerViewItemAnimators
上面给出其中一个比较出色的RecylerView库。
大家也可以根据自己的需要自行定制,ok就先介绍到这里。

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