第4次上级

package LHB.inherit;

public class Electricityfees 
{
   private int lastmonth,thismonth;/*上月电表读数，本月电表读数*/
   public Electricityfees()
   {
       
   }
   public Electricityfees(int lastmonth,int thismonth)
   {
       this.lastmonth=lastmonth;
       this.thismonth=thismonth;
   }
   public int getLastmonth() 
    {
    return lastmonth;
    }

   public void setLastmonth(int lastmonth) 
    {
    this.lastmonth = lastmonth;
    }

  public int getThismonth() 
   {
    return thismonth;
   }

  public void setThismonth(int thismonth) 
   {
    this.thismonth = thismonth;
   }
   public void print()
   {
       System.out.print("上月电表读数为："+lastmonth+"  ");
       System.out.println("这个月电表读数为："+thismonth+"  ");
   }
}

2. 编写“圆柱体”类及其测试类。

package LHB.inherit;

public class Cylinder 
{
     private int r,high; /*半径，高*/
     public Cylinder(int r,int high)
     {
         this.r=r;
         this.high=high;
     }
     public double area()
     {
         double s;
         s=3.14*r*r;
         return s;
     }
     public double volume()
     {
         double v;
         v=area()*high;
         return v;
     }
     public void print() 
     {
         System.out.println("圆的半径是："+r+"  "+"高是："+high);
         System.out.printf("圆的底面积是：%.2f  体积是：%.2f\n",area(),volume());
     }
    public int getR() 
    {
        return r;
    }
    public void setR(int r) 
    {
        this.r = r;
    }
    public int getHigh() 
    {
        return high;
    }
    public void setHigh(int high) 
    {
        this.high = high;
    }
    public static void main(String[] args) 
    {
        
     
    }

}

3.编写“四则运算类”及其测试类。

package LHB.inherit;

public class Elementary 
{
    private int num1,num2;
    private char Char;
    public Elementary(int num1,int num2)
    {
        this.num1=num1;
        this.num2=num2;
    }
    public Elementary(int num1,int num2,char Char)
    {
        this.num1=num1;
        this.num2=num2;
        this.Char=Char;
        System.out.print("操作结果是：");
        switch(Char)
        {
        case'+':  System.out.println(add());break;
        case'-':  System.out.println(minus());break;
        case'*':  System.out.println(multiply());break;
        case'/':  System.out.println(divide());break;
        }
    }
    public int add()
    {    
        int sum;
        sum=num1+num2;
        return sum;
    }
    public int minus() 
    {
         int minu;
         minu=num1-num2;
         return minu;
    }
    public int multiply()
    {
        int mult;
        mult=num1*num2;
        return mult;
    }
    public int divide()
    {
        int divid;
        divid=num1/num2;
        return divid;
    }
    public int getNum1() 
    {
        return num1;
    }
    public void setNum1(int num1) 
    {
        this.num1 = num1;
    }
    public int getNum2() 
    {
        return num2;
    }
    public void setNum2(int num2)
    {
        this.num2 = num2;
    }
    public char getChar() 
    {
        return Char;
    }
    public void setChar(char c)
    {
        Char = c;
    }
}