随机点名测试（随机数 类）

package lianxi;

public class Student { //学生类
private String name;
private String gender;
private String grade;
private int age;

public String getName() {
return name;
}

public String getGender() {
return gender;
}

public String getGrade() {
return grade;
}

public int getAge() {
return age;
}

public void setName(String name) {
this.name = name;
}

public void setGender(String gender) {
this.gender = gender;
}

public void setGrade(String grade) {
this.grade = grade;
}

public void setAge(int age) {
this.age = age;
}

public String toString() {
return "姓名：" + name + " 性别：" + gender + " 班级：" + grade + " 年龄："
+ age;
}

}

//学生列表（添加学生 随机点名..）

package lianxi;

import java.util.ArrayList;
import java.util.Scanner;

public class StudentList {
ArrayList<Student> stLt = new ArrayList<Student>();

public void addStudent() {
Scanner sc = new Scanner(System.in);
for (int i = 1; i < 3; i++) {
Student st = new Student();
System.out.println("添加第" + i + "个学生姓名：");
st.setName(sc.next());
System.out.println("添加第" + i + "个学生性别：");
st.setGender(sc.next());
System.out.println("添加第" + i + "个学生班级：");
st.setGrade(sc.next());
System.out.println("添加第" + i + "个学生年龄：");
st.setAge(sc.nextInt());
stLt.add(st);
}
}

public void deleteStudent(int tr) {
stLt.remove(tr);
}

public ArrayList<Student> printName() {
return stLt;
}

public String callName() {
/*
* Math.random() 方法生成[0,1)范围内的double类型随机数;
* Random类中的nextXxxx系列方法生成[0－n)的随机数； Math.random() 线程安全，多线程环境能被调用；
* 如无特殊需求，则使用(int)(Math.random()*n)的方式生成随机数即可。
*/
return stLt.get((int) (Math.random() * stLt.size())).getName()
+ stLt.get((int) (Math.random() * stLt.size())).getGender();// 此处学生的每个信息都是随机
// int index = new Random().nextInt(stLt.size());
// return stLt.get(index);
}
}

//测试

package lianxi;

public class MainCallName {
public static void main(String[] args) {
StudentList SL = new StudentList();
SL.addStudent();
System.out.println(SL.printName());
System.out.println(SL.callName());
SL.deleteStudent(1);
System.out.println(SL.printName());
System.out.println(SL.callName());
}

}