Question

    public class Driver
    {
        public static void main(String[] args)
        {
            Scanner keyboard = new Scanner(System.in);

            double circumference;
            double radius = 5.5;
            double pi = 3.1415926;
            double area = 0;

            Circle circleobject = new Circle();

            //Get Radius
            System.out.println("Circle's Radius");
            radius = keyboard.nextDouble();

            System.out.println("New Circle Object");

            Circle circle = new Circle();

            System.out.println("Area of Circle: " + Circle.getArea());
            System.out.println("Circumference of Circle: " + Circle.getCircumference());

        }
    }

我不明白如何使圆圈成为彩色圆圈。无论是红色，绿色还是蓝色。我需要添加什么才能使圆圈变成任何颜色？此外，似乎我无法使用Circle circleobject = new Circle（）行创建一个圆形对象; 我究竟做错了什么？这是我的圈子课。

    import java.awt.Color;
    import java.awt.Graphics;
    import java.awt.Graphics2D;

    /**
    * A Circle is a figure that has a radius, a circumference, 
    * and an area. 
    * @author Kelvynn Cayanan 
    * @version 02/09/2014
    */
    public class Circle
    {

        // Constants
        public static final double pi = 3.1415926; 

        // instance variables
        private double circumference;
        private double area; 
        private double radius;
        private Color color;


        /**
        * Constructs a circle of radius aRadius
        * @param aRadius is the radius of the circle
        */
        public Circle(double aRadius, Color type)
        {
             radius = aRadius; // assigns value to radius
             circumference = ( 2 * pi * radius); // arithmetic for circumference
             area = ( pi * radius * radius); // arithmetic for area
             color = type; // displays type of color

        }

        public void draw (Graphics circle)
        {
           circle.setColor (color);
        }

        /**
         */
        public double getRadius()
        {
            return radius;
        }

        public double getCircumference()
        {
            return circumference;
        }

        public double getArea()
        {
            return area;
        }

        public Color getColor()
        {
            return color;
        }
    }

Answer 1

一些事情：

您无法使用new Circle()创建圈子，因为您的Circle类中没有零参数构造函数，因此您必须使用new Circle(radius,color)构造函数。

其次，要绘制彩色圆圈，您需要在绘制方法中创建一个圆形，如下所示：

Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
Ellipse2D.Double cir = new Ellipse2D.Double();
cir.width = 2*radius;
cir.height = 2*radius;
cir.x = <upper left x co-ordinate>;
cir.y = <upper left y co-ordinate>;
g2d.draw(cir);
g2d.setPaint(color); // setting fill color
g2d.fill(cir);

在调用时，您需要在主程序中创建JFrame并在其paint方法中创建new circle并通过传递circle.draw(graphics) paint's graphics方法>

希望这有帮助

如何在驱动程序类中添加颜色到圆圈（java）

1 个答案: