RecyclerView简介

RecyclerView是Android一个更强大的控件,其不仅可以实现和ListView同样的效果,还有优化了ListView中的各种不足。其可以实现数据纵向滚动,也可以实现横向滚动(ListView做不到横向滚动)。接下来讲解RecyclerView的用法。

RecyclerView 基本用法

因为RecyclerView属于新增的控件,Android将RecyclerView定义在support库里。若要使用RecyclerView,第一步是要在build.gradle中添加对应的依赖库。

一、实现效果

单选效果：

多选效果：

二、前期准备

依赖的添加：

  //瀑布流LayoutManager
  implementation 'com.google.android:flexbox:1.0.0' 
  //RecyclerView
  implementation 'com.android.support:design:28.0.0'

三、使用方法

3.1、多选的实现

1、使用集合存储需要存储或者展示的数据

public static Set<Integer> positionSet = new HashSet<>(); //用于存储选择的位置
  private boolean selectMode = true; //选择模式 多选或者单选 true 多选
  public Set<String> checkTYpeNameSet = new HashSet<>(); //用于存储选择项的名称

2、实现流式布局的布局管理器

 mRecyclerView = (RecyclerView) findViewById(R.id.recycler);
    FlexboxLayoutManager manager = new FlexboxLayoutManager(this, FlexDirection.ROW, FlexWrap.WRAP){
      @Override
      public boolean canScrollVertically() {
        return false;
      }
    };
    mRecyclerView.setLayoutManager(manager);

3、单条点击事件的处理

mAdapter.setOnItemClickListener(new OnItemClickListener() {
      @Override
      public void OnItemClick(View view, int position) {
        addOrRemove(position);
      }
      @Override
      public void OnItemLongClick(View view, int position) {
      }
    });
 private void addOrRemove(int position) {
    if (positionSet.contains(position)) {
      // 如果包含，则撤销选择
      positionSet.remove(position);
      checkTYpeNameSet.remove(mListData.get(position).getTagName());
    } else {
      // 如果不包含，则添加
      positionSet.add(position);
      checkTYpeNameSet.add(mListData.get(position).getTagName());
    }
    if (positionSet.size() == 0) {
      // 如果没有选中任何的item，则退出多选模式
      mAdapter.notifyDataSetChanged();
      selectMode = false;
    } else {
      // 更新列表界面，否则无法显示已选的item
      mAdapter.notifyDataSetChanged();
    }
    Log.e("info",positionSet.toString());
    Toast.makeText(MultipleChoiceActivity.this,checkTYpeNameSet.toString(),Toast.LENGTH_SHORT).show();
  }

4、适配的写法

public class MultipleRecyclerAdapter extends RecyclerView.Adapter<MultipleRecyclerAdapter.ViewHolder> {
  private Context mContext;
  private List<TestBean> mListData = new ArrayList<>();
  private OnItemClickListener mOnItemClickListener;
  public void setOnItemClickListener(OnItemClickListener mOnItemClickListener) {
    this.mOnItemClickListener = mOnItemClickListener;
  }
  public MultipleRecyclerAdapter(Context mContext, List<TestBean> mListData) {
   // mListData = new ArrayList<>();
    this.mContext = mContext;
    this.mListData = mListData;
  }
  public void update(List<TestBean> list){
    if(list != null && list.size() > 0){
      mListData.addAll(list);
      notifyDataSetChanged();
    }
  }
  class ViewHolder extends RecyclerView.ViewHolder{
    TextView typeTv;
    CheckableLayout rootLayout;
    public ViewHolder(@NonNull View itemView) {
      super(itemView);
      typeTv = (TextView) itemView.findViewById(R.id.alive_type_tv);
      rootLayout = (CheckableLayout) itemView.findViewById(R.id.root_layout);
    }
  }
  @NonNull
  @Override
  public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    if(mContext == null){
      mContext = viewGroup.getContext();
    }
    View view = LayoutInflater.from(mContext).inflate(R.layout.item_recycler,viewGroup,false);
    return new ViewHolder(view);
  }
  @Override
  public void onBindViewHolder(@NonNull final ViewHolder holder, int position) {
    Set<Integer> positionSet = MultipleChoiceActivity.positionSet;
    //检查set里是否包含position，包含则显示选中的背景色，不包含则反之
    if (positionSet.contains(position)) {
      holder.rootLayout.setChecked(true);
      holder.typeTv.setTextColor(mContext.getResources().getColor(R.color.white));
    } else {
      holder.rootLayout.setChecked(false);
      holder.typeTv.setTextColor(mContext.getResources().getColor(R.color.grey_60));
    }
    TestBean bean = mListData.get(position);
    holder.typeTv.setText(bean.getTagName());
    if(mOnItemClickListener != null) {
      holder.itemView.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
          int pos = holder.getLayoutPosition();
          mOnItemClickListener.OnItemClick(holder.itemView, pos);
          holder.rootLayout.setChecked(true);
        }
      });
    }
  }
  @Override
  public int getItemCount() {
    return mListData != null ? mListData.size() : 0;
  }
}