详解分别用Kotlin和java写RecyclerView的示例

public class MainActivity extends AppCompatActivity implements RecyclerAdapter.OnItemClickListener{
    private RecyclerView mRecyclerView;
    private RecyclerView.LayoutManager mLayoutManager;
    private RecyclerAdapter mRecyclerAdapter;
    private ArrayListlist;

    @Override
    protected void onCreate(Bundlesaved InstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        RecyclerItem item;
        list = new ArrayList<>();
        item = new RecyclerItem();
        item.setName("No."+0);
        list.add(item);
        mRecyclerView = findViewById(R.id.recyclerView);
        mRecyclerAdapter = new RecyclerAdapter(this,list);
        mRecyclerAdapter.setOnItemClickListener(this);
        // 竖直方向的网格样式，每行一个Item
        mLayoutManager=new GridLayoutManager(this,3,OrientationHelper.VERTICAL,false);
        // 设置布局管理器
        mRecyclerView.setLayoutManager(mLayoutManager);
        // 设置adapter
        mRecyclerView.setAdapter(mRecyclerAdapter);
        // 设置Item添加和移除的动画
        mRecyclerView.setItemAnimator(newDefaultItemAnimator());
    }
    //adapter的按钮点击事件
    @Override
    public void onItemContentClick(Viewview,intposition) {
        //点击最后一个按钮增加一个item
        if(position == list.size()-1) {
          RecyclerItemitem=newRecyclerItem();
          item.setName("No."+(position+1));
          list.add(0,item);
          //更新RecyclerView
          mRecyclerAdapter.updateData(list);
        }else{
          Toast.makeText(this,"No."+position,Toast.LENGTH_SHORT).show();
        }
    }
}

public class RecyclerAdapter extends RecyclerView.Adapter{
  private ArrayList mData;
  private Context mContext;
  private OnItemClickListener onItemClickListener;
  public void setOnItemClickListener(OnItemClickListener listener) {
    this.onItemClickListener = listener;
  }
  public RecyclerAdapter(Context mContext,ArrayList mData){
    this.mData = mData;
    this.mContext = mContext;
  }

  //刷新整个list
  public void updateData(ArrayList data) {
    this.mData = data;
    notifyDataSetChanged();
  }

  //刷新局部list
  public void updateDataItem(ArrayList data, int itemnm) {
    this.mData = data;
    notifyItemChanged(itemnm);
  }

  @Override
  public View Holder onCreateViewHolder(ViewGroup parent, int viewType) {
    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.recycler_item, parent, false);
    ViewHolder viewHolder = new ViewHolder(v);
    return viewHolder;
  }

  @Override
  public void onBindViewHolder(final ViewHolder holder, int position) {
    holder.btn.setText(mData.get(position).getName());
    holder.btn.setOnClickListener(newView.OnClickListener() {
      @Override
      public void onClick(View v) {
        if(onItemClickListener != null) {
          int pos = holder.getLayoutPosition();
          onItemClickListener.onItemContentClick(holder.itemView, pos);
        }
      }
    });
  }

  @Override
  public int getItemCount() {
    return mData == null ? 0 : mData.size();
  }

  public static class ViewHolder extends RecyclerView.ViewHolder{
    Button btn;
    public ViewHolder(View itemView) {
      super(itemView);
      btn = itemView.findViewById(R.id.recycle_name);
    }
  }

  public interface OnItemClickListener{
    void onItemContentClick(View view, int position);
  }
}

public class RecyclerItem{
  String name;
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }

class MainActivity : AppCompatActivity(), MainAdapter.ItemClick{
  val items : MutableList = ArrayList()
  var mainAdapter : MainAdapter ?= null
  override fun onCreate(savedInstanceState:Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    //添加一个item
    var item : RecyclerItem
    item = RecyclerItem()
    item.name = "No."+0
    items.add(item)
    val recyclerView = findViewById(R.id.recyclerView) as RecyclerView
    recyclerView.layoutManager = GridLayoutManager(this, 3, OrientationHelper.VERTICAL, false)
    mainAdapter=MainAdapter(items, this)
    mainAdapter!!.setItemClickListener(this)
    recyclerView.adapter = mainAdapter
    recyclerView.itemAnimator = DefaultItemAnimator()
  }

  //adapter的按钮点击事件
  override fun OnItemClick(v : View, position : Int) {
    if(position == items.size - 1) {
      val item = RecyclerItem()
      item.name = "No." + (position + 1)
      items.add(0, item)
      //更新数据
      mainAdapter!!.updateData(items)
    }else{
      Toast.makeText(this,items.get(position).name, Toast.LENGTH_SHORT).show()
    }
  }
}

class MainAdapter : RecyclerView.Adapter{
  var items : List? = null
  var context : Context ?= null
  var itemClick : ItemClick ?= null
  constructor(items : List, context : Context){
    this.items = items
    this.context = context
  }
  fun setItemClickListener(itemClick : ItemClick){
    this.itemClick = itemClick
  }
  fun updateData(items : List){
    this.items = items
    notifyDataSetChanged()
  }
  override fun onBindViewHolder(holder : ViewHolder?, position : Int) {
    var name=items!!.get(position).name
    if(holder != null) {
      holder.textName.setText(name)
      holder.textName.setOnClickListener(View.OnClickListener{
        if(itemClick != null) {
          itemClick!!.OnItemClick(holder.itemView, position)
        }
      })
    }
  }
  override fun getItemCount():Int{
    return items!!.size
  }
  override fun onCreateViewHolder(parent : ViewGroup?, viewType : Int) : ViewHolder{
    val v = LayoutInflater.from(parent!!.context).inflate(R.layout.recycler_item, parent, false) as RelativeLayout
    val holder = ViewHolder(v)
    return holder
  }

  class ViewHolder(itemView : View?) : RecyclerView.ViewHolder(itemView) {
    var textName : TextView = itemView!!.findViewById(R.id.recycle_name) as TextView
  }

  interface ItemClick{
    fun OnItemClick(v : View, position : Int);
  }
}

class RecyclerItem{
  var name : String = ""
    get
    set
}

  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="100dp"
  android:layout_height="100dp">