mysql数据库中求圆的面积_Java 练习(Object 练习二)

例子一

GeometricObject.java

package com.klvchen.exer3;

public class GeometricObject {

protected String color;

protected double weight;

public GeometricObject() {

super();

this.color = "white";

this.weight = 1.0;

}

public GeometricObject(String color, double weight) {

super();

this.color = color;

this.weight = weight;

}

public String getColor() {

return color;

}

public void setColor(String color) {

this.color = color;

}

public double getWeight() {

return weight;

}

public void setWeight(double weight) {

this.weight = weight;

}

}

Circle.java

package com.klvchen.exer3;

public class Circle extends GeometricObject {

private double radius;

public Circle() {

super();

radius = 1.0;

}

public Circle(double radius) {

super();

this.radius = radius;

}

public Circle(double radius, String color, double weight) {

super(color, weight);

this.radius = radius;

}

public double getRadius() {

return radius;

}

public void setRadius(double radius) {

this.radius = radius;

}

//求圆的面积

public double findArea() {

return 3.14 * radius * radius;

}

//比较两个半径是否相等，若相等，返回 true

@Override

public boolean equals(Object obj) {

if(this == obj) {

return true;

}

if(obj instanceof Circle) {

Circle c = (Circle)obj;

return this.radius == c.radius;

}

return false;

}

@Override

public String toString() {

return "Circle [radius=" + radius + "]";

}

}

CircleTest.java

package com.klvchen.exer3;

public class CircleTest {

public static void main(String[] args) {

Circle circle1 = new Circle(2.3);

Circle circle2 = new Circle(2.3, "white", 2.0);

System.out.println("颜色是否相等: " + circle1.getColor().equals(circle2.getColor()));

System.out.println("半径是否相等: " + circle1.equals(circle2));

System.out.println(circle1);

System.out.println(circle2.toString());

}

}

运行结果: