6

我目前在家庭作业方面遇到了一些问题。

这是练习：

（绘制正弦和余弦函数）编写一个程序，将正弦函数绘制为红色，余弦函数绘制为蓝色。

提示： Pi 的 Unicode 是\u03c0。要显示 -2Pi，请使用 g.drawString("-2\u03c0", x, y)。对于像 sin(x) 这样的三角函数，x 的单位是弧度。使用以下循环将点添加到多边形p

for (int x = -170; x <= 170; x++) {
    p.addPoint(x + 200, 100 - (int)(50 * Math.sin((x / 100.0) * 2 * Math.PI)));

-2Pi 在 ( 100, 100 )，轴心在 ( 200, 100 )，2Pi 在 ( 300, 100 ) 使用Graphics类中的 drawPolyline 方法连接点。

好的，所以我的 sin 函数与练习中的函数有点不同，但它可以工作，所以它应该不是问题。另一方面，余弦函数，我很难找到它的代码，所以我的程序中没有它。

我还需要做的是将 -Pi 和 Pi 放在图表上它们可敬的位置。

所以，这里是代码。

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Polygon;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Exercise13_12 extends JFrame {

public Exercise13_12() {
    setLayout(new BorderLayout());
    add(new DrawSine(), BorderLayout.CENTER);
}

public static void main(String[] args) {
    Exercise13_12 frame = new Exercise13_12();
    frame.setSize(400, 300);
    frame.setTitle("Exercise13_12");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);

}

class DrawSine extends JPanel {

    double f(double x) {
        return Math.sin(x);
    }

    double g(double y) {
        return Math.cos(y);
    }

    protected void paintComponent(Graphics g) {
        super.paintComponent(g);

        g.drawLine(10, 100, 380, 100);
        g.drawLine(200, 30, 200, 190);

        g.drawLine(380, 100, 370, 90);
        g.drawLine(380, 100, 370, 110);
        g.drawLine(200, 30, 190, 40);
        g.drawLine(200, 30, 210, 40);

        g.drawString("X", 360, 80);
        g.drawString("Y", 220, 40);

        Polygon p = new Polygon();

        for (int x = -170; x <= 170; x++) {
            p.addPoint(x + 200, 100 - (int) (50 * f((x / 100.0) * 2
                    * Math.PI)));

        }

        g.drawPolyline(p.xpoints, p.ypoints, p.npoints);
        g.drawString("-2\u03c0", 95, 115);
        g.drawString("2\u03c0", 305, 115);
        g.drawString("0", 200, 115);
    }
 }
}

如果有人有时间帮助我，我将不胜感激。

4

4 回答 4

8

尝试这个：

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.Color;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class Exercise13_12 extends JFrame {

public Exercise13_12() {
    setLayout(new BorderLayout());
    add(new DrawSine(), BorderLayout.CENTER);
}

public static void main(String[] args) {
    Exercise13_12 frame = new Exercise13_12();
    frame.setSize(400, 300);
    frame.setTitle("Exercise13_12");
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setLocationRelativeTo(null);
    frame.setVisible(true);

}

class DrawSine extends JPanel {

    double f(double x) {
        return Math.sin(x);
    }

    double gCos(double y) {
        return Math.cos(y);
    }

    protected void paintComponent(Graphics g) 
    {
        super.paintComponent(g);

        g.drawLine(10, 100, 380, 100);
        g.drawLine(200, 30, 200, 190);

        g.drawLine(380, 100, 370, 90);
        g.drawLine(380, 100, 370, 110);
        g.drawLine(200, 30, 190, 40);
        g.drawLine(200, 30, 210, 40);

        g.drawString("X", 360, 80);
        g.drawString("Y", 220, 40);

        Polygon p = new Polygon();
        Polygon p2 = new Polygon();

       for (int x = -170; x <= 170; x++) {
            p.addPoint(x + 200, 100 - (int) (50 * f((x / 100.0) * 2
                    * Math.PI)));

        }

        for (int x = -170; x <= 170; x++) {
            p2.addPoint(x + 200, 100 - (int) (50 * gCos((x / 100.0) * 2
                    * Math.PI)));

        }

        g.setColor(Color.red);
        g.drawPolyline(p.xpoints, p.ypoints, p.npoints);
        g.drawString("-2\u03c0", 95, 115);
        g.drawString("2\u03c0", 305, 115);
        g.drawString("0", 200, 115);

        g.setColor(Color.blue);
        g.drawPolyline(p2.xpoints, p2.ypoints, p2.npoints);

    }
 }
}

在此处输入图像描述

基本上它是相同的代码，但你需要一个新的多边形来绘制它。然后我使用 Graphics 的 setColor() 函数设置颜色。

于 2013-11-11T20:03:04.573 回答
2

您可以将其添加到您的paintComponent方法中：

        //Draw pi and -pi
        g.drawString("-\u03c0", 147, 100);
        g.drawString("\u03c0", 253, 100);   

        //Create a new polygon
        Polygon p2 = new Polygon();

        //Add the points of the cosine
        for (int x = -170; x <= 170; x++) {
            p2.addPoint(x + 200, 100 - (int) (50 * g((x / 100.0) * 2
                    * Math.PI)));
        }
        //Draw the function
        g.drawPolyline(p2.xpoints, p2.ypoints, p2.npoints);

有了它，您可以获得所需的结果。

于 2013-11-11T20:03:37.637 回答
0

好的，既然程序完成了，我就结束了。

import java.awt.BorderLayout;
import java.awt.Graphics;
import java.awt.Polygon;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Exercise13_12 extends JFrame {

public Exercise13_12() {
setLayout(new BorderLayout());
add(new DrawSine(), BorderLayout.CENTER);
}

public static void main(String[] args) {
Exercise13_12 frame = new Exercise13_12();
frame.setSize(400, 300);
frame.setTitle("Exercise13_12");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);

}

class DrawSine extends JPanel {

double f(double x) {
    return Math.sin(x);
}

double gCos(double y) {
    return Math.cos(y);
}

protected void paintComponent(Graphics g) 
{
    super.paintComponent(g);

    g.drawLine(10, 100, 380, 100);
    g.drawLine(200, 30, 200, 190);

    g.drawLine(380, 100, 370, 90);
    g.drawLine(380, 100, 370, 110);
    g.drawLine(200, 30, 190, 40);
    g.drawLine(200, 30, 210, 40);

    g.drawString("X", 360, 80);
    g.drawString("Y", 220, 40);

    Polygon p = new Polygon();
    Polygon p2 = new Polygon();

   for (int x = -170; x <= 170; x++) {
        p.addPoint(x + 200, 100 - (int) (50 * f((x / 100.0) * 2
                * Math.PI)));

    }

    for (int x = -170; x <= 170; x++) {
        p2.addPoint(x + 200, 100 - (int) (50 * gCos((x / 100.0) * 2
                * Math.PI)));

    }

    g.setColor(Color.red);
    g.drawPolyline(p.xpoints, p.ypoints, p.npoints);
    g.drawString("-2\u03c0", 95, 115);
    g.drawString("-\u03c0", 147, 115);
    g.drawString("\u03c0", 253, 115);  
    g.drawString("2\u03c0", 305, 115);
    g.drawString("0", 200, 115);

    g.setColor(Color.blue);
    g.drawPolyline(p2.xpoints, p2.ypoints, p2.npoints);

  }
 }
}

对于以后可能遇到与我相同问题的任何人。

感谢大家帮助我，永远感激。

于 2013-11-11T20:20:51.270 回答
0

一探究竟 .....

public class GuiBasicstest {    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        // TODO code application logic herei
        guiBasics gb = new guiBasics();
        JFrame jf = new JFrame();
        jf.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        jf.setSize(500,500);
        jf.add(gb);            
        jf.setVisible(true);            
    }        
}    

................................................................................
package guibasics;    
import java.awt.Graphics;
import javax.swing.JPanel;

/**
 *
 * @author ALI
 */
public class guiBasics extends JPanel{
    //Graphics g = null;

    public void paintComponent(Graphics g){

        //super.paintComponent(g);
        for(double i = 0; i<200;i++){
            double y= Math.sin(i);
            draw(i,y,g);
        }
    }
    private void draw(double x , double y,Graphics g ){ 
         double x1, y1;
         x+=10;
         y+=10;
         x*=10;
         y*=30;

       x1=x+1;
       y1=y+1;
       Double d = new Double(x);
       int a = d.intValue();
       int b = (new Double(y)).intValue();
       int c = (new Double(x1)).intValue();
       int e = (new Double(y1)).intValue();
       g.drawLine(a, b, c, e);
    }
}
于 2015-03-03T19:11:46.453 回答