Android RecyclerView 的简单使用

如何使用

1.build.gradle中添加该类
compile 'com.android.support:recyclerview-v7:28.0.0'
2.视图层中定义RecyclerView

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

    </android.support.v7.widget.RecyclerView>

3.绑定RecyclerView

        RecyclerView rv = findViewById(R.id.rv);
        RvAdapter rvAdapter = new RvAdapter(list);
        rv.setAdapter(rvAdapter);
//        rv.setLayoutManager(new GridLayoutManager(this,4));
        rv.setLayoutManager(new 
LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false));

RecyclerView中有两个必须的设置,setLayoutManager()和setAdapter.
LayoutManager有两种,GridLayoutManager,LinearLayoutManager.
GridLayoutManager使用了2个参数的构造;GridLayoutManager(Context context, int spanCount)
context :上下文
spancout: 每行显示的数量。
LinearLayoutManager使用了3个参数的构造,LinearLayoutManager(Context context, int orientation, boolean reverseLayout)。
context:上下文
orientation:方向,垂直还是水平
reverseLayout：是否倒置,true为倒置
定义Adapter之前创建子视图
activity_item

<android.support.constraint.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
    android:layout_height="wrap_content">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:background="@drawable/border"
        >
        <ImageView
            android:layout_width="100dp"
            android:layout_height="100dp"
            android:layout_gravity="center"
            android:src="@mipmap/ic_launcher"
            />
        <TextView
            android:layout_width="250dp"
            android:layout_height="100dp"
            android:layout_gravity="center"
            android:gravity="center"
            android:id="@+id/rv_text"
            android:background="@drawable/border_blue"
            />
    </LinearLayout>


</android.support.constraint.ConstraintLayout>

4.定义Adapter

public class RvAdapter extends RecyclerView.Adapter<RvAdapter.MyViewHolder> {

   private List<String> list;

   private MyClickListener myClickListener;

   public void setMyClickListener(MyClickListener myClickListener) {
       this.myClickListener=myClickListener;
   }

   public RvAdapter(List<String> list) {
       this.list=list;
   }

   @NonNull
   @Override
   public MyViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
       //绑定子视图
       View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.activity_item, viewGroup, false);
       MyViewHolder myViewHolder=new MyViewHolder(view);
       return myViewHolder;
   }

   @Override
   public void onBindViewHolder(@NonNull MyViewHolder myViewHolder, final int i) {
       TextView textView =myViewHolder.itemView.findViewById(R.id.rv_text);
       textView.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               myClickListener.setTextClickListener(i);
           }
       });
       textView.setText(list.get(i));
       myViewHolder.itemView.setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               myClickListener.setOnClickListener(i);
           }
       });
       myViewHolder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
           @Override
           public boolean onLongClick(View v) {
               myClickListener.setOnLongClickListener(i);
               return false;
           }
       });
   }

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

   //定义视图管理器
   class MyViewHolder extends RecyclerView.ViewHolder {
       public MyViewHolder(@NonNull View itemView) {
           super(itemView);
       }
   }
   
   //事件监听
   public interface MyClickListener{
       void setOnClickListener(int i);
       void setOnLongClickListener(int i);
       void setTextClickListener(int i);
   }
}

Adapter中重写了三个方法
onCreateViewHolder:用来获取子视图控制器,MyViewHolder继承RecyclerView.ViewHolder类。
onBindViewHolder:用来获取子视图里的控件,第二个参数表示第几个item。
getItemCount():表示页面需要显示的item数量。
RecyclerView只有item的点击事件没有长按事件,使用事件监听给外部暴露长按事件。

rvAdapter.setMyClickListener(new RvAdapter.MyClickListener() {
            @Override
            public void setOnClickListener(int i) {
                Toast.makeText(MainActivity.this,"点击了第 "+ i +"个",Toast.LENGTH_SHORT).show();
            }

            @Override
            public void setOnLongClickListener(int i) {
                Toast.makeText(MainActivity.this,"长按了第 "+ i +"个",Toast.LENGTH_SHORT).show();
            }

            @Override
            public void setTextClickListener(int i) {
                Toast.makeText(MainActivity.this,"点击了第 "+ i +"个text",Toast.LENGTH_SHORT).show();
            }
        });

5.效果