RecyclerView（滚动控件）的用法

Posted 2020-08-31 yl007

1.首先在build.gradle中添加依赖库

　　compile ‘com.android.support:recyclerview-v7:24.2.1‘

2.修改activity_main.xml

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

3.类似ListView，新建一个适配器FruitAdapter，定义一个ViewHolder内部类，传入一个View参数，重写onCreateViewHolder（）、onBindViewHolder（）、getItemCount（）

public class FruitAdapter extends RecyclerView.Adapter<FruitAdapter.ViewHolder>{
    private List<Fruit> mFruitList;
    static class ViewHolder extends RecyclerView.ViewHolder{
        ImageView Fruitimage;
        TextView FruitName;
　　//创建ViewHolder内部类
        public ViewHolder(View view){
            super(view);
            fruitImage = (ImageView)findViewById(R.id.fruit_image);
            fruitName = (TextView)findViewById(R.id.fruit_name);
        }
    }
    public FruitAdapter(List<Fruit> fruitList){
         mFruitList = fruitList;
    }
　　//创建ViewHolder实例
    @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;
    }
　　//为子项赋值
    @Override
    public void onBindViewHolder(ViewHolder holder,int position){
        Fruit fruit = mFruitList.get(position);
        holder.fruitImage.setImageResource(fruit.getImageId());
        holder.fruitName.setText(fruit.getName());
    }
　　//子项的数目
    @Override
    public int getItemCount(){
        return mFruitList.size();
    }
}

 4.在MainAcitivity中编写RecyclerView代码

public class MainActivity extends AppCompatActivity{
    private Lsit<Fruit> fruitList = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initFruits();    //初始化水果数据
        RecyclerView recyclerView = (RecyclerView)findViewById(R.id.recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);    //指定布局方式
        FruitAdapter adapter = new FruitAdapter(fruitList);
        recyclerView.setAdapter(adapter);
    }
    private void initFruits(){
        for(int i=0;i<2;i++){
            Fruit apple = new Fruit("Apple",R.drawable.apple_pic);
            fruitList.add(apple);
            ......
        }
    }
}

 

RecyclerView特殊用法

　　ListView只能实现纵向滚动，而RecyclerView可以实现横向和瀑布流。

　　横向滚动：

　　　　修改fruit_item.xml中LinearLayout布局方向：android:orientation="vartical";　　并将ImageView和TextView设置成水平居中。

　　　　在MainActivity中onCreate（）添加:layoutManager.setOrientation(LinearLayoutManger.HORIZONTAL);

　　瀑布流：

　　　　调整fruit_item.xml

　　　　在MainActivity中onCreate（）添加:staggeredGridLayoutManager layoutManager = staggeredGridLayoutManager(3,StaggeredGridLayoutManger.VERTICAL);　//1参：列数，2参：排列方向

 

RecyclerView的点击事件

　　

......
    @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 = mFuritList.get(position);
                Toast.makeText(v.getContext(),"you clicked image"+fruit.getName(),Toast.LENGTH_SHORT).show();
            }
        });
        return holder;
    }
......