我目前在作业方面遇到了一些问题。

这是练习:

(Plot the sine and cosine functions) Write a program that plots the sine function in red and the cosine function in blue.

hint: The Unicode for Pi is \u03c0. To display -2Pi, use g.drawString("-2\u03c0", x, y). For a trigonometric function like sin(x), x is in radians. Use the following loop to add the points to a polygon p

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

-2Pi is at (100, 100), the center of the axis is at (200, 100), and 2Pi is at (300, 100) Use the drawPolyline method in the Graphics class to connect the points.

好的，所以我的 sin 函数与练习中的函数有点不同，但它有效，所以应该不是问题。另一方面，余弦函数，我找不到它的代码，所以我的程序中没有它。

我还需要做的是将 -Pi 和 Pi 放在图表上的适当位置。

所以，这是代码。

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。

最佳答案

试试这个:

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);

    }
 }
}

基本上都是相同的代码，但是您需要一个新的多边形来绘制它。然后我使用图形的 setColor() 函数设置颜色。

关于java - 绘制正弦和余弦函数，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19914476/