Java,Python,Scala比较（二）类与继承

逃离我推掉我的手 2022-06-05 00:40 125阅读 0赞

UML图如下：  
![这里写图片描述][SouthEast]  
完整的Java代码如下：  
SimpleGeometricObject.java

public class SimpleGeometricObject { 
        private String color = "white";
        private boolean filled;
        private java.util.Date dateCreated;
    
        /**Construct a default geometric object */
        public SimpleGeometricObject(){
            dateCreated = new java.util.Date();
        }
    
        /**Construct a geometric object with the specified color * and filled value*/
        public SimpleGeometricObject(String color, boolean filled) {
            dateCreated = new java.util.Date();
            this.color = color;
            this.filled = filled;
        }
    
        /**Return color*/
        public String getColor() {
            return color;
        }
    
        /**set a new color*/
        public void setColor(String color) {
            this.color = color;
        }
    
        /**Return filled. Since filled is boolean, * its better method is named isFilled*/
        public boolean isFilled() {
            return filled;
        }
    
        /**Set a new filled*/
        public void setFilled(boolean filled) {
            this.filled = filled;
        }
    
        /**Get dateCreated*/
        public java.util.Date getDateCreated(){
            return dateCreated;
        }
    
        /**Return a string representation of this object*/
        public String toString() {
            return "created on "+dateCreated+"\ncolor: "+color+" and filled: "+filled;
        }
    }

CircleFromSimpleGeometricObject.java

public class CircleFromSimpleGeometricObject extends SimpleGeometricObject{ 
        private double radius;
    
        public CircleFromSimpleGeometricObject() {}
    
        public CircleFromSimpleGeometricObject(double radius) {
            this.radius = radius;
        }
    
        public CircleFromSimpleGeometricObject(double radius, String color, boolean filled) {
            super(color, filled);
            this.radius = radius;   
        }
    
        /**Return radius*/
        public double getRadius() {
            return radius;
        }
    
        /**Set a new radius*/
        public void setRadius(double radius) {
            this.radius = radius;
        }
    
        /**Return area*/
        public double getArea() {
            return radius*radius*Math.PI;
        }
    
        /**Return diameter*/
        public double getDiameter() {
            return 2*radius;
        }
    
        /**Return perimeter*/
        public double getPerimeter() {
            return 2*radius*Math.PI;
        }
    
        /**Return the circle info*/
        public void printCircle() {
            System.out.println("The circle is created "+getDateCreated()+" and the radius is "+radius);
        }   
    }

RectangleFromSimpleGeometricObject.java

public class RectangleFromSimpleGeometricObject extends SimpleGeometricObject{ 
        private double width;
        private double height;
    
        public RectangleFromSimpleGeometricObject() {}
    
        public RectangleFromSimpleGeometricObject(double width, double height) {
            this.width = width;
            this.height = height;
        }
    
        public RectangleFromSimpleGeometricObject(double width, double height, String color, boolean filled) {
            super(color, filled);
            this.width = width;
            this.height = height;
        }
    
        /**Return width*/
        public double getWidth() {
            return width;
        }
    
        /**Set a new width*/
        public void setWidth(double width) {
            this.width = width;
        }
    
        /**Return height*/
        public double getHeight() {
            return height;
        }
    
        /**Set a new width*/
        public void setHeight(double height) {
            this.height=height;
        }   
    
        /**Return area*/
        public double gerArea() {
            return width*height;
        }
    
        /**Return perimeter*/
        public double getPerimeter() {
            return 2*(width+height);
        }
    }

Test.java

public class Test{
        public static void main(String[] args){
            CircleFromSimpleGeometricObject circle = new CircleFromSimpleGeometricObject(1,"red", true);
            System.out.println("A circle "+circle.toString());
            System.out.println("The color is "+circle.getColor());
            System.out.println("The radius is "+circle.getRadius());
            System.out.println("The area is "+circle.getArea());
            System.out.println("The diameter is "+circle.getDiameter());
    
            RectangleFromSimpleGeometricObject rect = new RectangleFromSimpleGeometricObject(2,4);
            System.out.println("\nA rectangle is "+rect.toString());
            System.out.println("The area is "+rect.gerArea());
            System.out.println("The perimeter is "+rect.getPerimeter());
        }
    }

完整的Python代码如下：

import math
    import datetime
    
    class SimpleGeometricObject(object):
        def __init__(self, color, filled):
            self.__color = color
            self.__filled = filled 
            self.__date = datetime.datetime.now()
    
        def getColor(self):
            return self.__color
    
        def setColor(self, color):
            self.__color = color
    
        def isFilled(self):
            return self.__filled
    
        def setFilled(self, filled):
            self.__filled = filled
    
        def getDateCreated(self):
            return self.__date.strftime("%Y/%m/%d/%H:%M")
    
        def __str__(self):
            return  "is created on "+self.getDateCreated()+", color: "+self.__color\
                    +" and filled: "+str(self.__filled)
    
    class CircleFromSimpleGeometricObject(SimpleGeometricObject):
        def __init__(self, color, filled, radius):
            super(CircleFromSimpleGeometricObject, self).__init__(color, filled)
            self.__radius = radius
    
        def getRadius(self):
            return self.__radius
    
        def setRadius(self, radius):
            self.__radius = radius
    
        def getArea(self):
            return self.__radius*self.__radius*math.pi
    
        def getPerimeter(self):
            return 2*self.__radius*math.pi
    
        def getDiameter(self):
            return self.__radius*2
    
        def printCircle(self):
            print(self.__str__()+" and the radius is "+str(self.__radius))
    
    class RectangleFromSimpleGeometricObject(SimpleGeometricObject):
        def __init__(self, color, filled, width, height):
            super(RectangleFromSimpleGeometricObject, self).__init__(color, filled)
            self.__width = width
            self.__height = height
    
        def getWidth(self):
            return self.__width
    
        def setWidth(self, width):
            self.__width = width
    
        def getHeight(self):
            return self.__height
    
        def setHeight(self, height):
            self.__height = height 
    
        def getArea(self):
            return self.__width * self.__height
    
        def getPerimeter(self):
            return 2*(self.__width+self.__height)
    
    def main():
        circle = CircleFromSimpleGeometricObject("red", True, 5)
        print("A circle ", circle)
        print("The color is ", circle.getColor())
        print("The radius is %s"%circle.getRadius())
        print("The area is %s"%circle.getArea())
        print("The diameter is %s"%circle.getDiameter())
    
        rect = RectangleFromSimpleGeometricObject("white", False, 3, 4);
        print("\nA rectangle", rect);
        print("The area is %s"%rect.getArea());
        print("The perimeter is %s"%rect.getPerimeter());
    
    main()

完整的Scala代码如下：

import java.util.Date;
    import scala.math._;
    
    object demo extends App { 
      class SimpleGeometricObject (private var color:String="white", private var filled:Boolean=false){ 
        private var dateCreated:java.util.Date = new Date()
    
        def getColor() = color
    
        def setColor(color:String) = {
       this.color = color}
    
        def isFilled() = filled
    
        def setFilled(filled:Boolean) = {
       this.filled = filled}
    
        def getDateCreated() = dateCreated 
    
        override def toString()= "created on "+dateCreated+"\ncolor: "+color+" and filled: "+filled
      }
    
      class CircleFromSimpleGeometricObject(color:String, filled:Boolean, private var radius:Double) extends SimpleGeometricObject(color,filled){ 
        def this() = this("white", false, 1.0)
    
        def getRadius() = radius
    
        def setRadius(radius:Double) = {
       this.radius = radius}
    
        def getArea() = radius*radius*Pi
    
        def getDiameter() = radius*2
    
        def getPerimeter() = radius*2*Pi
    
        def printCircle() = {println("The circle is created "+getDateCreated+" and the radius is "+radius)}
      }
    
      class RectangleFromSimpleGeometricObject(color:String, filled:Boolean, private var width:Double, private var height:Double) extends SimpleGeometricObject(color, filled) { 
        def this() = this("white", false, 1.0, 1.0)
    
        def getWidth() = width
    
        def setWidth(width:Double) = {
       this.width = width}
    
        def getHeight() = height
    
        def setHeight(height:Double) = {
       this.height = height}
    
        def getArea() = width*height
    
        def getPerimeter() = 2*(width+height)
      }
    
      var circle = new CircleFromSimpleGeometricObject("red", true, 2.0)
      println("A circle is "+circle.toString())
      println("The color is "+circle.getColor())
      println("The radius is "+circle.getRadius())
      println("The area is "+circle.getArea())
      println("The diameter is "+circle.getPerimeter()) 
    
      var rect = new RectangleFromSimpleGeometricObject("green", true, 3.0, 4.0)
      println("\nA rectangle is "+rect.toString())
      println("The area is "+rect.getArea())
      println("The perimeter is "+rect.getPerimeter())
    }

读者可以自己从上述代码中体验三种语言的相同点与不同之处，显然，Python与Scala语言较为简洁~~

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本次分享到此结束，欢迎大家交流~~

[SouthEast]: /images/20220605/67b3ad3e9e4a4924aba3ee3a16ae97b0.png