RecyclerView初使

RecyclerView是什么

官方介绍

RecyclerView与ListView 有什么不同

RecyclerView与ListView 对比浅析：缓存机制

使用RecyclerView展示列表的步骤

1. 在build.gradle中引用

 implementation 'androidx.recyclerview:recyclerview:1.1.0'

1. 在布局中申明

<androidx.recyclerview.widget.RecyclerView android:id="@+id/history_listview"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:divider="@color/color_000000_10"
    android:dividerHeight="0dp"
    android:fitsSystemWindows="true"
    tools:context="com.idoucx.timething.activity.HistoryListActivity"
    app:layoutManager="LinearLayoutManager"
    tools:listitem="@layout/layout_history" />

注意布局中设置布局中的的layoutManager

  <!--app后面用于设置LayoutManager-->
  xmlns:app="http://schemas.android.com/apk/res-auto"
  app:layoutManager="LinearLayoutManager"

否则就会不展示Layout

RecyclerView: No layout manager attached; skipping layout

也可以通过代码指定：

  mRecyclerView.setLayoutManager(new LinearLayoutManager(this));

2. 新建Adapter类继承自RecyclerView.Adapter<T>

 class HistoryAdapter extends RecyclerView.Adapter<HistoryAdapter.ViewHolder> {

 }
 

2.1 添加构造方法

 HistoryAdapter(HistoryListActivity parent,
                                      List<RecordInfo> items,
                                      boolean twoPane) {}

2.2 实现onCreateViewHolder和创建ViewHodler 加载布局文件，将View和ViewHolder绑定

public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext())
                    .inflate(R.layout.layout_history, parent, false);
            return new ViewHolder(view);
        }

这里ViewHolder的要继承自 RecyclerView.ViewHolder

 class ViewHolder extends  RecyclerView.ViewHolder {
            @BindView(R.id.history_item_day)
            TextView dayTv;
            @BindView(R.id.history_item_color_view)
            TextView colorView;
            @BindView(R.id.history_item_content_tv)
            TextView contentTv;
            @BindView(R.id.history_item_time_tv)
            TextView timeTv;
            @BindView(R.id.history_item_line1)
            TextView line1;
            @BindView(R.id.history_item_line2)
            TextView line2;
            @BindView(R.id.history_item_delete)
            MaterialButton deleteBtn;

            ViewHolder(View view) {
                super(view);
                ButterKnife.bind(this, view);
            }
        }

2.3 实现getItemCount(),得到子项的个数

     public int getItemCount() {
            LogUtil.e("本次展示的大小是：>"+mRecordInfos.size());
            return mRecordInfos.size();
        }

2.4 实现onBindViewHolder(@NonNull ViewHolder holder, int position)方法，将数据和viewHolder绑定，数据怎么展示，展示的逻辑是什么都写到这里

3. 将Adapter和RecyclerView绑定

      adapter = new HistoryAdapter(this,recordInfos,false);
        recyclerView.setAdapter(adapter);