The basic use of RecycleView and Adapter

1. Create layout files, word_fragment to put Recycle, word_fragment_grad_cell to put a small unit

word_fragment layout:

word_fragment_grad_cell layout :( card layout)

2. Create a class adapter wordFragmentAdapter

package com.example.ngsl.wordFragment

import android.content.Intent
import android.net.Uri
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.ListAdapter
import androidx.recyclerview.widget.RecyclerView
import com.example.ngsl.R
import com.example.ngsl.room.Word
import kotlinx.android.synthetic.main.word_fragment_grad_cell.view.*

//适配器：告诉view有哪些内容，并且如何填充view
class WordFragmentAdapter : ListAdapter<Word, MyViewHolder>(DiffCallBack) {
    //比较器，比较每一行的对象
    object DiffCallBack : DiffUtil.ItemCallback<Word>() {
        override fun areItemsTheSame(oldItem: Word, newItem: Word): Boolean {
            //比较是不是同一个对象
            return oldItem.wordId == newItem.wordId
        }
        override fun areContentsTheSame(oldItem: Word, newItem: Word): Boolean {
            //比较内容是否相同
            return oldItem == newItem
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        //加载view，就是每一个小单元word_fragment_grad_cell
        val view = LayoutInflater.from(parent.context).inflate(R.layout.word_fragment_grad_cell, parent, false)
        val holder = MyViewHolder(view)
        holder.itemView.apply {
            //将监听事件放在这，就不会每次加载一个item时新创建监听事件
            val onClickListener = View.OnClickListener {
                val uri = Uri.parse("https://m.youdao.com/dict?le=eng&q=${this.textViewEnglish.text}")
                Intent(Intent.ACTION_VIEW).apply {
                    this.data = uri
                    holder.itemView.context.startActivity(this)
                }
            }
            this.textViewEnglish.setOnClickListener(onClickListener)
            this.imageView.setOnClickListener(onClickListener)
        }
        return holder
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        //加载资源
        holder.itemView.apply {
            val item = getItem(position)
            this.textViewWordId.text = item.wordId.toString()
            this.textViewEnglish.text = item.english
        }
    }
}

//这个很重要
class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)

3. Load adapter in the wordFragment

fragment is preferably operated in the onActivityCreated

package com.example.ngsl.wordFragment

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.GridLayoutManager
import com.example.ngsl.R
import kotlinx.android.synthetic.main.word_fragment.*

class WordFragment : Fragment() {

	//ViewModel 管理数据的
    private lateinit var viewModel: WordViewModel

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.word_fragment, container, false)
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)

        //创建适配器
        val wordFragmentAdapter = WordFragmentAdapter()
        recycleView.apply {
            adapter = wordFragmentAdapter
            //页面布局，1列
            layoutManager = GridLayoutManager(requireContext(), 1)
        }

        //ViewModel
        viewModel = ViewModelProvider(this).get(WordViewModel::class.java)
        viewModel.allWord.observe(viewLifecycleOwner, Observer {
            //为适配器提供数据
            wordFragmentAdapter.submitList(it)
        })
    }
}

4.GitHub source connection

The entire project has many components, but only part of what you need: https://github.com/YDDUONG/NGSL-English
If you find it useful, praise it a point