2024-05-16 09:21:26
public class Student {
private String no;//
private String name;//姓名
private String sex;//性别
private String age;//年龄
private float score;//成绩
public Student(String no, String name, String sex, String age , float score) {
this.no = no;
this.name = name;
this.sex = sex;
this.age = age;
this.score = score;
}
public static void main(String[] args) {
//new一个学生对象,并使用构造方法初始化成员变量
Student S01 = new Student("s01", "张三", "男", "20", 99);
System.out.println("学号:"+S01.no+"\n"+
"姓名:"+S01.name+"\n"+
"性别"+S01.sex+"\n"+
"年龄"+S01.age+"\n"+
"成绩"+S01.score);
}
}
抽象类
并不是所有种类的事物都可以被实例化,换而言之,有的种类只是一种抽象概念,现实中并没有实际存在的对应物。
比如:假设所有的动物都会叫,我们可以定义一个类“动物”,定义类中的一个成员函数“叫”,我们知道猫的叫声,也知道狗的叫声,然而“动物”是如何“叫”的?我们根本无法实现它。
所以,我们引入了抽象类的概念,抽象类是无法被实例化的,无法声明抽象类的对象。
通常,用abstract修饰的类是抽象类;C++中包含纯虚函数的类是抽象类;Java中含有抽象方法的类是抽象类;继承了纯虚函数而没有实现它的类也是抽象类。
抽象类只能被用作基类,作用体现在:
1、约束派生类必须实现的成员函数或方法。
2、不同派生类中同名的成员函数实现不同,体现了多态性。
2024-05-16 13:05:11
class Student{
private String stuNum; //学号
private String name; //姓名
private String sex; //性别
private int age; //年龄
private float mark; //java成绩
//无参构造方法
public Student(){
}
//有参构造方法
public Student(String stuNum, String name, String sex,
int age, float mark){
this.stuNum = stuNum;
this.name = name;
this.sex = sex;
this.age = age;
this.mark = mark;
}
}
怎么创建5个学生实例呢,急求,谢了。并求出这五个学生实例的最高分,最低分,总分,及平均分
创建学生实例:
Student student1 = new Student("001","小明","男",15,85);
Student student2 = new Student("002","小红","女",14,68.5);
Student student3 = new Student("003","小王","男",16,93);
Student student4 = new Student("004","小陈","女",17,43);
Student student5 = new Student("005","小李","男",16,75.5);
最高分:
float maxMark = student1.mark;
if(maxMark <= student2.mark) maxMark = student2.mark;
else if(maxMark <= student3.mark) maxMark = student3.mark;
else if(maxMark <= student4.mark) maxMark = student4.mark;
else if(maxMark <= student5.mark) maxMark = student5.mark;
return maxMark;
最低分:
float minMark = student1.mark;
if(minMark > student2.mark) minMark = student2.mark;
else if(minMark > student3.mark) minMark = student3.mark;
else if(minMark > student4.mark) minMark = student4.mark;
else if(minMark > student5.mark) minMark = student5.mark;
return minMark;
总分:
float sumMark = student1.mark + student2.mark + student3.mark + student4.mark + student5.mark;
平均分:
float averageMark = sumMark / 5;
PS:当然,上面的方法其实是效率很低的。
2024-05-16 01:52:12
2024-05-16 08:13:42