[安卓]ListView 与 RecyclerView的比较

ListView与RecyclerView在在app应用非常广泛，相对于其他的view（button textview）来说比较复杂，接下来我将讲一下创建的流程以及两者的不同。

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代码来自《第一行代码》

秋天到了，果园大丰收了，现在着急的事情，就是把水果收集好放进仓库里。

ListView

1. 首先肯定要先把仓库准备好,腾一块地方出来，在布局中添加ListView。

   
   

   
   

2. 把装水果的框子准备好，创建fruit_item布局。

   
   

3. 主角登场啦，咱们的搬运工，创建类FruitAdapter。

他需要干什么呢？

先贴出源码，下面解释

package com.example.listviewtest;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;

public class FruitAdapter extends ArrayAdapter {

private int resourceId;

public FruitAdapter(Context context, int textViewResourceId,
List objects) {
super(context, textViewResourceId, objects);
resourceId = textViewResourceId;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
Fruit fruit = getItem(position); // 获取当前项的Fruit实例
View view;
ViewHolder viewHolder;
if (convertView == null) {
view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
viewHolder = new ViewHolder();
viewHolder.fruitImage = (ImageView) view.findViewById (R.id.fruit_image);
viewHolder.fruitName = (TextView) view.findViewById (R.id.fruit_name);
view.setTag(viewHolder); // 将ViewHolder存储在View中
} else {
view = convertView;
viewHolder = (ViewHolder) view.getTag(); // 重新获取ViewHolder
}
viewHolder.fruitImage.setImageResource(fruit.getImageId());
viewHolder.fruitName.setText(fruit.getName());
return view;
}

class ViewHolder {

ImageView fruitImage;

TextView fruitName;

}

}

搬运工的工作就是，返回一个装满水果的框框

• 拿到一个水果

• 找到一个框框

• 把水果放到框框里

• 把框框返回（结局自然回到里仓库）

  1. 拿到一个水果

     Fruit fruit = getItem(position);

  2. 找到一个框框

     View view;
     view = LayoutInflater.from(getContext()).inflate(resourceId, parent, false);
     ImageView fruitImage = (ImageView) view.findViewById(R.id.fruit_image)
     TextView fruitName = (TextView) view.findViewById(R.id.fruit_name)

  3. 把水果放到框框里

     viewHolder.fruitImage.setImageResource(fruit.getImageId());
     viewHolder.fruitName.setText(fruit.getName());
     源码里面有两布优化，自己想想哦。

  4.把框框返回

  return view;

RecylerView

还是老步骤，首先准备好仓库，在准备好框框

1. 准备好仓库，腾一块地方出来

   
   

   <android.support.v7.widget.RecyclerView
   android:id="@+id/recycler_view"
   android:layout_width="match_parent"
   android:layout_height="match_parent" />

2. 准备好框框，和上面一样

   
   

3. 请出我们更加聪明的搬运工了

先贴出源码，下面解释

package com.example.recyclerviewtest;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder>{

private List mFruitList;

static class ViewHolder extends RecyclerView.ViewHolder {
View fruitView;
ImageView fruitImage;
TextView fruitName;

public ViewHolder(View view) {
super(view);
fruitView = view;
fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
fruitName = (TextView) view.findViewById(R.id.fruit_name);
}
}

public FruitAdapter(List fruitList) {
mFruitList = fruitList;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item, parent, false);
final ViewHolder holder = new ViewHolder(view);
holder.fruitView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = holder.getAdapterPosition();
Fruit fruit = mFruitList.get(position);
Toast.makeText(v.getContext(), "you clicked view " + fruit.getName(), Toast.LENGTH_SHORT).show();
}
});
holder.fruitImage.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
int position = holder.getAdapterPosition();
Fruit fruit = mFruitList.get(position);
Toast.makeText(v.getContext(), "you clicked image " + fruit.getName(), Toast.LENGTH_SHORT).show();
}
});
return holder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {
Fruit fruit = mFruitList.get(position);
holder.fruitImage.setImageResource(fruit.getImageId());
holder.fruitName.setText(fruit.getName());
}

@Override
public int getItemCount() {
return mFruitList.size();
}
}

多了好多诶，其实，咱们聪明的搬运工制造了更多的工具，真是方便了好多。
现在搬运工只需要干两件事情了

• 找到一个水果

• 把水果放到框子里

  public void onBindViewHolder(ViewHolder holder, int position) {
  Fruit fruit = mFruitList.get(position);
  holder.fruitImage.setImageResource(fruit.getImageId());
  holder.fruitName.setText(fruit.getName());
  }

  没错，只需要两部，其他的事情都靠聪明的搬运工制造出来的自动小车，送回到仓库了，是不是很酷。

• 现在创造出我们的工具

  static class ViewHolder extends RecyclerView.ViewHolder {
  View fruitView;
  ImageView fruitImage;
  TextView fruitName;

  public ViewHolder(View view) {
  super(view);
  fruitView = view;
  fruitImage = (ImageView) view.findViewById(R.id.fruit_image);
  fruitName = (TextView) view.findViewById(R.id.fruit_name);
  }
  }

  这个工具记得他应该去仓库中腾出来的位置

• 再看看工具是怎么运作的

  @Override
  public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
  View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item, parent, false);
  ViewHolder holder = new ViewHolder(view);
  return holder;
  }

  首先他会和仓库联系一下，然后就会自动运回仓库啦。