简单Java类

简单Java类：

1. 类名要有意义，能知道这个类是干嘛使的

2. 类中的成员变量需要用 private 封装，封装之后的属性必须提供 setter, getter方法

3. 类中可以提供任意多个构造方法，但是一定要保留一个无参构造

4. 类中不允许出现任何输出语句，所有的信息交给被调用处输出

 

实例1：定义一个Book类，属性有 title, price

class Book{
    
    //定义成员变量
    private String title;
    private double price;
    
    //定义Setter,getter
    public void setTitle(String title){
        this.title = title;
    }
    public void setPrice(double price){
        this.price = price;
    }
    public String getTitle(){
        return title;
    }
    public double getPrice(){
        return price;
    }
    
    public void getInfo(){
        return "书名：" + title + " 价格：" + price;
    }
    
    //定义构造方法
    public Book(){}
    public Book(String title, double price){
        this.title = title;
        this.price = price;
    }
}

 

实例2：定义一个雇员类 Emp

//定义一个雇员类Emp，属性有（empno,ename,job,sal,comm）

class Emp{
    
    //定义成员变量
    private int empno;
    private String ename;
    private String job;
    private double sal;
    private double comm;
    
    public Emp(){}
    public Emp(int empno, String ename, String job, double sal, double comm){
        
        this.empno = empno;
        this.ename = ename;
        this.job = job;
        this.sal = sal;
        this.comm = comm;
    }
    
    //setter,getter
    public void setEmpno(int empno){
        this.empno = empno;
    }
    public void setEname(String ename){
        this.ename = ename;
    }
    public void setJob(String job){
        this.job = job;
    }
    public void setSal(double sal){
        this.sal = sal;
    }
    public void setComm(double comm){
        this.comm = comm;
    }
    
    public String getInfo(){
        return "雇员编号：" + empno +"\n" +
                "雇员姓名：" + ename + "\n" +
                "工作：" + job + "\n" +
                "薪水" + sal + "\n" +
                "佣金" + comm;
        
    }
    
}