RecyclerView是可以滑動的的列表，能自己設計資料顯示的版面長怎樣，當資料數量過多超出RecyclerView的範圍時會變成可以滑動的狀態

添加RecyclerView

RecyclerView為內建的元件所以直接拉進Xml就可以了

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:layout_width="409dp"
        android:layout_height="300dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintVertical_bias="0.0" />
</androidx.constraintlayout.widget.ConstraintLayout>

創建一個item.xml

這裡是用來設計每一筆資料顯示時的版面

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="TextView"
        android:textSize="25dp" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="TextView"
        android:textSize="25dp" />
</LinearLayout>

創建RecyclerView的Adapter

package com.example.recyclerview_demo;

import android.view.LayoutInflater;
import android.view.TextureView;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;
import java.util.HashMap;

public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder> {
    ArrayList<HashMap<String, String>> arrayList = new ArrayList<>();
    //接收在activity的arrayList的假資料
    public Adapter(ArrayList<HashMap<String, String>> arrayList) {
        this.arrayList = arrayList;
    }

    @NonNull
    @Override
    public Adapter.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        //item布局生成
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.item, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull Adapter.ViewHolder holder, int position) {
        //控制元件的顯示
        holder.setData(position);
    }

    @Override
    public int getItemCount() {
        //顯示資料的數量
        return arrayList.size();
    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        TextView ID ,num;
        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            //綁定item.xml裡的元件
            ID = itemView.findViewById(R.id.textView);
            num = itemView.findViewById(R.id.textView2);
        }
        //提取假資料的函式
        void setData(int position){
            ID.setText(arrayList.get(position).get("ID"));
            num.setText(arrayList.get(position).get("num"));
        }
    }
}

activity_main

package com.example.recyclerview_demo;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Random;

public class MainActivity extends AppCompatActivity {
    RecyclerView recyclerView;
    Adapter adapter;
    ArrayList<HashMap<String, String>> arrayList = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        for (int i=1;i<=50;i++){
            HashMap<String, String> hashMap = new HashMap<>();
            hashMap.put("ID", "序號:" + i);
            hashMap.put("num", "數量:" + (new Random().nextInt(80)+20));
            arrayList.add(hashMap);
        }
        //綁定recyclerView元件
        recyclerView = findViewById(R.id.recyclerview);
        //recyclerView初始化
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        //每筆資料間的分隔線(可加可不加)
        //recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));
        //將資料丟給adapter處理
        adapter = new Adapter(arrayList);
        //adapter處理完後再交給recyclerView去顯示
        recyclerView.setAdapter(adapter);
    }
}

HashMap

HashMap 在這裡我用來創建假資料
它是以key-vlue的放式來存取
只要把HashMap丟到arrayList這樣就創建好假資料了
最後交給Adapter去處理

for (int i=1;i<=50;i++){
    HashMap<String, String> hashMap = new HashMap<>();
    hashMap.put("ID", "序號:" + i);
    hashMap.put("num", "數量:" + (new Random().nextInt(80)+20));
    arrayList.add(hashMap);
}

顯示結果