點名器：用于随機點名

import java.util.ArrayList;

import java.util.Random;

public class CallNameDemo{

 public static void main (String args[]){

  ArrayList array = new ArrayList();

  addStudent(array);

  look(array);

  randomStudentName(array);

 }

 //存儲

 public static void addStudent(ArrayList array){

  Student s1 = new Student();

  s1.name = “張三”;s1.age = 12;

  Student s2 = new Student();

  s2.name = “李四”;s2.age = 18;

  Student s3 = new Student();

  s3.name = “王五”;s3.age = 16;

  Student s4 = new Student();

  s4.name = “趙六”;s4.age = 14;

  array.add(s1);array.add(s2);

  array.add(s3);array.add(s4);

 }

 //檢視

 public static void look(ArrayList array){

  for (int a = 0 ; a < array.size(); a++){

   System.out.println(array.get(a).name+" "+array.get(a).age+“歲”);

  }

 }

 //抽取

 public static void randomStudentName(ArrayList array){

  int random = new Random().nextInt(array.size());

  System.out.println("幸運學生是 :   “+array.get(random).name+” "+array.get(random).age+“歲”);

 } 

}

class Student{

 int age ;

 String name;

}