根据Java中的用户输入绘制一个圆

Question

我一遍又一遍地试图找到解决这个问题的方法,但我似乎无法理解如何解决它.

我正在尝试编写一个简单的程序,在程序中绘制一个带有这些规范的圆圈:

1. 使用输入框(JOptionPane)询问用户圆的半径.
2. 在输入框(JOptionPane)中询问用户圆圈的x和y坐标.
3. 计算圆的周长.
4. 计算圆的面积.
5. 圆形图下方的显示区域和周长.

不知何故,它不会绘制圆,并计算周长和面积.能帮我找到解决这个问题的方法吗？

这是我的代码:

-------主要-------

package circleSquarePackage;

import circleSquarePackage.Circle;

import javax.swing.JOptionPane;
import javax.swing.JFrame;

public class CircleTester {

    public static void main(String[] args) 
        {

        JFrame frame = new JFrame();

        // Display Circle in the frame
        frame.setSize(600, 500);
        frame.setTitle("CircleSquare");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        // Create Circle Components
        Circle round = new Circle();
        frame.add(round);

        frame.setVisible(true);

    }

}

--------其他类---------

package circleSquarePackage;

import javax.swing.JComponent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Ellipse2D.Double;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Color;

import javax.swing.JOptionPane;


public class Circle extends JComponent {
    // Member instance field
    private Ellipse2D.Double sphere;
    private int radius;
    double circumference, area;

    String x1; // starting x co-ordinate
    String y1; // starting y co-ordinate
    String r1; // radius for circle
    String draw;

    int x = 0;
    int y = 0;
    int r = 0;


    // Default constructor
    public Circle()
    {
        sphere = new Ellipse2D.Double();
    }

    // User defined constructor
    public Circle(int xAxis, int yAxis, int rad)
    {
        rad = r;
        xAxis = x;
        yAxis = y;
        sphere = new Ellipse2D.Double(xAxis, yAxis, rad, rad);
    }

    // Accessor methods
    public double calcCircumference()
    {
    return circumference = 2 * Math.PI * radius;
    }

    public double calcArea()
    {
        return area = Math.PI * radius * radius;
    }

    // Methods
    public void inputX()
    {
        x1 = JOptionPane.showInputDialog(null, "Input center (x value): ");
        x = Integer.parseInt(x1);
    }

    public void inputY()
    {
        y1 = JOptionPane.showInputDialog(null, "Input center (y value): ");
        y = Integer.parseInt(y1);

    }

    public void inputRadius()
    {
        r1 = JOptionPane.showInputDialog(null, "Input radius: ");
        r = Integer.parseInt(r1);
    }

    public void paintComponent(Graphics g)
    {
        // Cast 1D to 2D graphics
        Graphics2D g2 = (Graphics2D) g;

        g2.setColor(Color.BLUE); // set circle color to blue
        g2.fill(sphere);
        g2.draw(sphere);

        g2.setColor(Color.BLUE);
        g2.drawString("Circumference = " + calcCircumference(), 5, 450);
        g2.drawString("Area = " + calcCircumference(), 200, 450);
    }
}

---

基于PEESKILLET答案的更新

圈级

package circleSquarePackage;

import javax.swing.JComponent;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Ellipse2D.Double;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Color;
import java.awt.Dimension;

import javax.swing.JOptionPane;


public class Circle extends JComponent {
    // Member instance field
    private Ellipse2D.Double sphere;
    private int radius;
    double circumference, area;


    // Default constructor
    public Circle()
    {
        sphere = new Ellipse2D.Double();
    }

    public void setSphere(Ellipse2D.Double sphere) {
        this.sphere = sphere;
        repaint();
    }

    // User defined constructor
    public Circle(int xAxis, int yAxis, int rad)
    {
        sphere = new Ellipse2D.Double(xAxis, yAxis, rad, rad);
    }

    // Accessor methods
    public double calcCircumference()
    {
    return circumference = 2 * Math.PI * radius;
    }

    public double calcArea()
    {
        return area = Math.PI * radius * radius;
    }

    // Methods
    public void inputX()
    {
        int x = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter x"));
        double y = sphere.y; // why is there a double y here when it asks for x?
        Ellipse2D.Double newSphere = new Ellipse2D.Double(x, y, size, size);
        setSphere(newSphere);
    }

    public void inputY()
    {
        int y = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter y"));
        double x = sphere.x; 
        Ellipse2D.Double newSphere = new Ellipse2D.Double(x, y, size, size);
        setSphere(newSphere);
    }

    public void inputRadius() 
    {
        // is this how I do for radius?
        int r = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter radius"));
        int size = r * 2;
        Ellipse2D.Double newSphere = new Ellipse2D.Double(x, y, size, size);
        setSphere(newSphere);
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;

        g2.setColor(Color.BLUE); // set circle color to blue
        g2.fill(sphere);
        g2.draw(sphere);

        g2.drawString("Circumference: " + calcCircumference(), 5, 490);

    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(600, 500);
    }
}

-------- CircleTester类--------

package circleSquarePackage;

import circleSquarePackage.Circle;

import javax.swing.JOptionPane;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Ellipse2D.Double;

public class CircleTester {
    /*
    private static Ellipse2D.Double getCircle() {
        int x = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter integer for x-coordinates:"));
        int y = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter integer for y-coordinates:"));
        int radius = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter radius of circle:"));
        int size = radius * 2;
        return new Ellipse2D.Double(x, y, size, size);
    }*/

    public static void main(String[] args) 
    {
        // Is there a way to call the inputX(), inputY(), and inputRadius() here?

        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new JFrame();


                frame.setTitle("CircleSquare");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                Circle round = new Circle();
                frame.add(round);

                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);

                /*
                Ellipse2D.Double newCircle = getCircle();
                round.setSphere(newCircle);
                */
            }
        });

    }

}

Answer 1

在你的无参数Circle构造函数中,你在获取值之前创建了一个sphere(默认Ellipse2D.Double值).您应该sphere 基于这些值创建,就像您在三个arg构造函数中一样

来自Ellipse2D.Double

Ellipse2D.Double()
构造一个新的Ellipse2D,初始化为位置(0,0)和大小(0,0).

另一种设计可能性

1. setSphere在Circle类中有一个方法,你可以设置椭圆和重绘

   public void setSphere(Ellepse2D.Double sphere) {
       this.sphere = sphere;
       repaint();
   }
   

2. JOptionPane显示框架后,请完成所有静止.看起来是对的.然后当你的价值观,你可以调用setSphere的Circle类,有一个新的Ellipse2D.Double,它会在面板中显示.

其他说明:

• 在进行自定义绘制时,最好覆盖getPreferredSize()绘制的组件,然后调用pack()框架,而不是setSize()

• 请参阅初始线程.应该在Event Dispatch Thread上发布Swing应用程序.

• 此外,您不需要课程中的冗余x, y, etc值Circle.它们已经被Ellipse对象所控制.如果你需要得到一些值,只是从,即得到它sphere.x,sphere.y.等

这是我上面提到的建议的重构.(您还需要进行一些检查,以确保数字实际上是类型.我很懒)

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;

public class CircleTester {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                JFrame frame = new JFrame();

                frame.setTitle("CircleSquare");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

                Circle round = new Circle();
                frame.add(round);

                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);

                Ellipse2D.Double newCircle = getCircle();
                round.setSphere(newCircle);
            }
        });

    }

    private static Ellipse2D.Double getCircle() {
        int x = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter x"));
        int y = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter x"));
        int radius = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter x"));
        int size = radius * 2;
        return new Ellipse2D.Double(x, y, size, size);
    }
}

class Circle extends JComponent {

    private Ellipse2D.Double sphere;

    public Circle() {
        sphere = new Ellipse2D.Double();
    }

    public void setSphere(Ellipse2D.Double sphere) {
        this.sphere = sphere;
        repaint();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;

        g2.setColor(Color.BLUE); // set circle color to blue
        g2.fill(sphere);
        g2.draw(sphere);

    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(300, 300);
    }
}

UPDATE

我想知道如何在公共void inputX(),public void inputY()和public void inputRadius()下的Circle类中放置JOptionPane请求用户输入,然后在CircleTester类的main中调用那些？

你能做的就是在每个方法中调用JOPtionPane.假设你想获得x,然后调用JOptionPane,并根据该值,使用旧值并使用新x从旧椭圆创建一个新的Ellipse.然后打电话setSphere.就像是

public void inputX() {
    int x = Integer.parseInt(JOptionPane.showInputDialog(null, "Enter x"));
    double y = sphere.y;
    double height = sphere.height;
    double width = sphere.width;
    Ellips2D.Double newSpehere = new Ellipse2D.Double(x, y, width, height);
    setSphere(newSphere);
}

你也可以这样做.这样,当您调用方法时,一旦输入,它将只更改一个变量.

您也可以使用一种方法来获取所有变量,就像我在我的示例中所做的那样.