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Requirement
In this Assignment, you should write a class that, given a circle’s radius, has methods that return the circle’s area, diameter, and circumference. In case you have forgotten, the equations for a circle’s area, diameter, and circumference is given below.
代码语言：javascript复制diameter = 2r
circumference = 2πr
Based on Chapter 3, Programming Challenge # 8 Circle class in your textbook. Your output is given below.
代码语言：javascript复制The circle's area is 88.2472631
The circle's diameter is 10.6
The circle's circumference is 33.300854
Write a separate class called CircleDemo with a main method that asks the user for the circle’s radius, creates a Circle object, and then reports the circle’s area, diameter, and circumference using the circle’s getter methods.
Analysis
本题需要的数学背景见Pi，需要实现一个Circle类，以及对应的方法，如setRadius()，getRadius()，getArea()，getDiameter()，getCircumference()。 本题较为简单，注意数据类型，精度以及输入输出格式即可。
Tips
下面是ClicleDemo类的实现
代码语言：javascript复制class CircleDemo {
private double radius;
private static final PI = 3.14159;
public CircleDemo() {}
public void setRadius() {
this.radius = radius;
}
public double getRadius() {
return this.radius;
}
public double getArea() {
return CircleDemo.PI * this.radius * this.radius;
}
public double getDiameter() {
return 2 * this.radius;
}
public double getCircumference() {
return 2 * CircleDemo.PI * this.radius;
}
}
