1 RecyclerView

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1 RecyclerView

RecyclerView

  • 调用

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    RecyclerView recyclerView = findViewById(R.id.recycler_view);
    LinearLayoutManager layoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);
    FruitAdapter adapter = new FruitAdapter(fruitList);
    recyclerView.setAdapter(adapter);
    • 控件
      • id: recycler_view
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        <androidx.recyclerview.widget.RecyclerView
          android:id="@+id/recycler_view"
          android:layout_width="match_parent"
          android:layout_height="match_parent" />
      • id: fruit_name, fruit_image

  • 适配器 Adapter

    • 定义式

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

    • 创建内部类 ViewHolder

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

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

    • 构造方法 FruitAdapter（接收数据源）

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      public FruitAdapter(List<Fruit> fruitList){
          mFruitList = fruitList;
      }

    • mFruitList: 

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      private List<Fruit> mFruitList;

    • 必须继承的方法
      onCreateViewHolder()
      onBindViewHolder()
      getItemCount()

      • onCreateViewHolder() 创建ViewHolder实例
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          public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            //加载fruit_item布局
          View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.fruit_item, parent, false);
          //将布局传入ViewHolder
          ViewHolder holder = new ViewHolder(view);
          //返回ViewHolder实例
          return holder;
        }
      • onBindViewHolder()
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        public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
          //通过当前项获得Fruit实例
            Fruit fruit = mFruitList.get(position);
            //将数据设置到ViewHolder的ImageView和TextView中
            holder.fruitImage.setImageResource(fruit.getImageId());
            holder.fruitName.setText(fruit.getName());
        }

        用于对RecyclerView子项的数赋值，每个子项滚动到屏幕的时候执行

      • getItemCount()
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        public int getItemCount() {
          //返回数据源长度
          return mFruitList.size();
        }