ArrayList 实现随机点名

package lijun.cn.demo1;

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

public class CallName {

    public static void main(String[] args) {
        ArrayList<Student> arr=new ArrayList<Student>();
         //添加
        add(arr);
        //遍历
        printArrayList(arr);
        //随机
        randomStudentName(arr);

    }

    private static void randomStudentName(ArrayList<Student> arr) {
        Random r=new Random();
        int num=r.nextInt(arr.size());
        Student s=arr.get(num);
        System.out.println("=============================");
        System.out.println(s.name+"  "+s.age);
    }

    private static void printArrayList(ArrayList<Student> arr) {
        for(int i=0;i<arr.size();i++){
            Student s=arr.get(i);
            System.out.println(s.name+"  "+s.age);
        }

    }

    private static void add(ArrayList<Student> arr) {
        Student s1=new Student();
        s1.name="张无忌";
        s1.age=22;

        Student s2=new Student();
        s2.name="无双";
        s2.age=21;

        Student s3=new Student();
        s3.name="建宁";
        s3.age=20;

        Student s4=new Student();
        s4.name="龙儿";
        s4.age=25;

        arr.add(s1);
        arr.add(s2);
        arr.add(s3);
        arr.add(s4);

    }

}