ListView與RecyclerView在在app應用非常廣泛，相對於其他的view（button textview）來說比較複雜，接下來我將講一下建立的流程以及兩者的不同。

程式碼來自《第一行程式碼》

秋天到了，果園大豐收了，現在著急的事情，就是把水果收集好放進倉庫裡。

ListView

1. 首先肯定要先把倉庫準備好,騰一塊地方出來，在佈局中新增ListView。

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
   
        <ListView
            android:id="@+id/list_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent" >
        </ListView>
   
    </LinearLayout>
    
   

2. 把裝水果的框子準備好，建立fruit_item佈局。

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="horizontal"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
   
        <ImageView
            android:id="@+id/fruit_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
   
        <TextView
            android:id="@+id/fruit_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_vertical"
            android:layout_marginLeft="10dp" />
   
    </LinearLayout>
    
   

3. 主角登場啦，咱們的搬運工，建立類FruitAdapter。

他需要幹什麼呢？

先貼出原始碼，下面解釋

    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<Fruit> {
    
        private int resourceId;
    
        public FruitAdapter(Context context, int textViewResourceId,
                            List<Fruit> objects) {
            super(context, textViewResourceId, objects);
            resourceId = textViewResourceId;
        }
    
        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            Fruit fruit = getItem(position); // 獲取當前項的Fruit例項
            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); // 將ViewHolder儲存在View中
            } else {
                view = convertView;
                viewHolder = (ViewHolder) view.getTag(); // 重新獲取ViewHolder
            }
            viewHolder.fruitImage.setImageResource(fruit.getImageId());
            viewHolder.fruitName.setText(fruit.getName());
            return view;
        }
    
        class ViewHolder {
    
            ImageView fruitImage;
    
            TextView fruitName;
    
        }
    
    }
 

搬運工的工作就是，返回一個裝滿水果的框框

• 拿到一個水果
• 找到一個框框
• 把水果放到框框裡
• 把框框返回（結局自然回到裡倉庫）

  1. 拿到一個水果

      Fruit fruit = getItem(position);

  2. 找到一個框框

      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. 把水果放到框框裡

      viewHolder.fruitImage.setImageResource(fruit.getImageId());
      viewHolder.fruitName.setText(fruit.getName());

     原始碼裡面有兩布優化，自己想想哦。

  4.把框框返回

        return view;

RecylerView

還是老步驟，首先準備好倉庫，在準備好框框

1. 準備好倉庫，騰一塊地方出來

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
   
        <android.support.v7.widget.RecyclerView
            android:id="@+id/recycler_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
   
    </LinearLayout>

2. 準備好框框，和上面一樣

    <?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="5dp" >
   
        <ImageView
            android:id="@+id/fruit_image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center_horizontal" />
   
        <TextView
            android:id="@+id/fruit_name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="left"
            android:layout_marginTop="10dp" />
   
    </LinearLayout>

3. 請出我們更加聰明的搬運工了

   先貼出原始碼，下面解釋

   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<Fruit> 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<Fruit> 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();
    }

   }

多了好多誒，其實，咱們聰明的搬運工製造了更多的工具，真是方便了好多。
現在搬運工只需要幹兩件事情了

• 找到一個水果

• 把水果放到框子裡

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

  沒錯，只需要兩部，其他的事情都靠聰明的搬運工製造出來的自動小車，送回到倉庫了，是不是很酷。

• 現在創造出我們的工具

    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);
        }
    }

  這個工具記得他應該去倉庫中騰出來的位置

• 再看看工具是怎麼運作的

    @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;
    }

  首先他會和倉庫聯絡一下，然後就會自動運回倉庫啦。