RecyclerView的简单使用

Posted 2021-11-27 eswd

简单讲讲RecyclerView的使用：（这里用的是androidX，而不是之前的supprot-v7，用法基本一样）

1、引入recyclerView的依赖库：

implementation 'androidx.recyclerview:recyclerview:1.0.0'

2、主布局内添加RecyclerView的布局控件

<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>
        
</LinearLayout>

3、添加一个适配器，继承自RecyclerView.Adapter

public class RecyclerAdapter extends RecyclerView.Adapter<RecyclerAdapter.ViewHolder> {
    //这里的要实现ViewHolder，ListView里没有强制使用ViewHolder
    Context context;
    List<String> list;
    public RecyclerAdapter(Context context, List<Data> list) {   
      //这里添加一个构造方法，方便使用
        this.context = context;
        this.list = list;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        //实例化ViewHolder，并通过inflate来把ItemView传递过去
        ViewHolder viewHolder=new ViewHolder(View.inflate(context,R.layout.recycler_item,null));
        return viewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        holder.textView.setText(list.get(position).getTiTle());
    }

    @Override
    public int getItemCount() {
        return list.size();
        //返回列表的大小
    }

    class ViewHolder extends RecyclerView.ViewHolder {
        TextView textView;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            textView=itemView.findViewById(R.id.textView);
        }
    }
}

4、Data类

public class Data {

    String title;
    
    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }
}

5、Activity

public class MainActivity extends AppCompatActivity {

    List<Data> list;
    RecyclerAdapter adapter;
    RecyclerView recyclerView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        recyclerView=findViewById(R.id.recyclerView);
        list=new ArrayList<>();
        adapter=new RecyclerAdapter(this,list); //实例化适配器
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        //设置布局管理器，如果实现网格布局，可以用GridLayoutManager
        recyclerView.setAdapter(adapter);  //设置适配器
    }
}

最后讲一点，因为RecyclerView没有实现单击和长按的功能，所以要自己写

在适配器里添加回调接口实现：

@Override
  public void onBindViewHolder(@NonNull ViewHolder holder, final int position) {
      holder.textView.setText(list.get(position).getTitle());
      
      /*********************************/
      holder.itemView.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
              onItemClickListener.onItemClick(position);
          }
      });
      holder.itemView.setOnLongClickListener(new View.OnLongClickListener() {
          @Override
          public boolean onLongClick(View v) {
              onItemLongClickListener.onItemLongClick(position);
              return true;
          }
      });
      
      
      /**************************************/
  }

  /*实现单击和长按*/
  OnItemLongClickListener onItemLongClickListener;
  OnItemClickListener onItemClickListener;
  interface OnItemClickListener{
      void onItemClick(int position);
  }
  interface OnItemLongClickListener{
      void onItemLongClick(int position);
  }

  public void setOnItemClickListener(OnItemClickListener onItemClickListener){
      this.onItemClickListener=onItemClickListener;
  }
  public void setOnItemLongClickListener(OnItemLongClickListener onItemLongClickListener){
      this.onItemLongClickListener=onItemLongClickListener;
  }
  /*实现单击和长按*/

---Activity

adapter.setOnItemClickListener(new RecyclerAdapter.OnItemClickListener() {
            @Override
            public void onItemClick(int position) {
                Toast.makeText(MainActivity.this, "pos"+position, Toast.LENGTH_SHORT).show();
            }
        });