Android-RecyclerView实用解析 Recycler.Adapter 的写法与介绍

圆号本昊

发布于 2021-09-24 12:20:28

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发布于 2021-09-24 12:20:28

文章被收录于专栏：github@hornhuang

与复杂难用的 ListView 相比，RecyclerView 清晰的思路，简明的用法，强大的功能，无不预示着一个时代的过去，这里我主要讲讲 RecyclerView 基本使用

RecyclerView 的使用主要分三部分

Adapter 配适器的使用
recyclerView 设置配适器
更新 RecyclerView 的内容

首先我们举个配适器的例子

public class ColopediaAdapter extends RecyclerView.Adapter<ColopediaAdapter.ViewHolder>{

    private List<Comment> mList ;

    class ViewHolder extends RecyclerView.ViewHolder {

        private ImageView authorIcon;
        private TextView  praiseNum;
        private TextView  authorName;
        private TextView  commontContent;
        private ImageView touchGood;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            authorIcon = itemView.findViewById(R.id.comment_author_image);
            authorName = itemView.findViewById(R.id.comment_author_name);
            praiseNum  = itemView.findViewById(R.id.comment_praise_nums);
            commontContent = itemView.findViewById(R.id.comment_content);
            touchGood = itemView.findViewById(R.id.touch_good);
        }
    }

    public ColopediaAdapter(List<Comment> mList){
        this.mList = mList;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
        View view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.clopedia_list_item_view, viewGroup, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull final ViewHolder viewHolder, final int i) {
        viewHolder.authorIcon.setImageResource(mList.get(i).getImageId());
        viewHolder.authorName.setText(mList.get(i).getAuthorId());
        viewHolder.commontContent.setText(mList.get(i).getCommentContent());
        viewHolder.touchGood.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
            }
        });

    }

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

}

不管是哪个配适器首先要继承自 Recycler.Adapter ，然后都包含这几个基本要素：

ViewHolder	新建一个 ViewHolder 类，用于绑定控件
onCreateViewHolder	绑定每个 item 的布局
onBindViewHolder	实现每个控件的具体功能和点击事件

写完配适器后我们就可以实现改 RecyclerView 了

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_clopedia_huashupihua);

    iniViews();
    iniList();
    iniRecyclerView();

}

private void iniViews(){
    mComment = new ArrayList<>();
    recyclerView = (RecyclerView) findViewById(R.id.colopedia_recycler);
    commentSubmit = (TextView) findViewById(R.id.comment_submit);
    editText = (EditText) findViewById(R.id.colopedia_comment_content);

    commentSubmit.setOnClickListener(this);
}

private void iniRecyclerView(){
    LinearLayoutManager manager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(manager);
    adapter = new ColopediaAdapter(mComment);
    recyclerView.setAdapter(adapter);
}

private void iniList(){
    mComment = MainActivity.comments;
}

可以看到，实现过程主要包括

List	在一个 List 对象里，存放 item 的队列
adapter	根据 List 生成 Adapter
LinearLayoutManager	为 RecyclerView 配适管理器

更新 items 的内容

String content = editText.getText().toString();
                mComment.add(new Comment(R.drawable.baikepinglun_1_head, "小道夫",
                    content, 0));
                MainActivity.comments = mComment;
                adapter.notifyDataSetChanged();

这里给出 Comment 类的具体内容

public class Comment {

    private int imageId;          // 用户头像
    private String authorId;      // 用户名称
    private String commentContent;// 评论内容
    private int praiseNum;        // 点赞数目
    private boolean isPraised = false;//判断是否点赞

    /*
    构造方法
     */
    public Comment(int imageId, String authorId, String commentContent, int praiseNum) {
        this.imageId = imageId;
        this.authorId = authorId;
        this.commentContent = commentContent;
        this.praiseNum = praiseNum;
    }

    /*
    get()  &  set()
     */

    public int getImageId() {
        return imageId;
    }

    public void setImageId(int imageId) {
        this.imageId = imageId;
    }

    public String getAuthorId() {
        return authorId;
    }

    public void setAuthorId(String authorId) {
        this.authorId = authorId;
    }

    public String getCommentContent() {
        return commentContent;
    }

    public void setCommentContent(String commentContent) {
        this.commentContent = commentContent;
    }

    public int getPraiseNum() {
        return praiseNum;
    }

    public void setPraiseNum(int praiseNum) {
        this.praiseNum = praiseNum;
    }

    public boolean isPraised() {
        return isPraised;
    }

    public void setPraised(boolean praised) {
        isPraised = praised;
    }
}

这里给出活动的具体内容

public class Clopediahuashupihua extends AppCompatActivity implements View.OnClickListener {

    private RecyclerView recyclerView;
    private List<Comment> mComment;
    private TextView commentSubmit;
    private ColopediaAdapter adapter;
    private EditText editText;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_clopedia_huashupihua);

        iniViews();
        iniList();
        iniRecyclerView();

    }

    private void iniViews(){
        mComment = new ArrayList<>();
        recyclerView = (RecyclerView) findViewById(R.id.colopedia_recycler);
        commentSubmit = (TextView) findViewById(R.id.comment_submit);
        editText = (EditText) findViewById(R.id.colopedia_comment_content);

        commentSubmit.setOnClickListener(this);
    }

    private void iniRecyclerView(){
        LinearLayoutManager manager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(manager);
        adapter = new ColopediaAdapter(mComment);
        recyclerView.setAdapter(adapter);
    }

    private void iniList(){
        mComment = MainActivity.comments;
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()){
            case R.id.comment_submit:
                String content = editText.getText().toString();
                mComment.add(new Comment(R.drawable.baikepinglun_1_head, "小道夫",
                    content, 0));
                MainActivity.comments = mComment;
                adapter.notifyDataSetChanged();
                break;

            default:

                break;
        }

    }
}