Question

基于java图形类实现函数曲线的绘制

原题:利用java编制一个简单得GUI程序得应用,要求在窗体上绘制f(x)=x^2+sin(x)在区间[-3,3]的函数图像.开发平台 eclipse/netbeans/Jbuilder
求高手啊~~~

Answer 1

import javax.swing.*;
import javax.swing.event.*;
import java.awt.*;
import com.bruceeckel.swing.*;// 这个包你要自己去下，此处无法上传，整个程序你还要修改一下，以满足f(x)=x^2+sin(x)在区间[-3,3]的函数图像

class SineDraw extends JPanel {
static final int SCALEFACTOR = 200;
int cycles;
int points;
double[] sines;
int[] pts;
SineDraw() { setCycles(5); }
public void setCycles(int newCycles) {
cycles = newCycles;
points = SCALEFACTOR * cycles * 2;
sines = new double[points];
pts = new int[points];
for(int i = 0; i < points; i++) {
double radians = (Math.PI/SCALEFACTOR) * i;
sines[i] = Math.sin(radians);
}
repaint();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
int maxWidth = getWidth();
double hstep = (double)maxWidth/(double)points;
int maxHeight = getHeight();
for(int i = 0; i < points; i++)
pts[i] = (int)(sines[i] * maxHeight/2 * .95
+ maxHeight/2);
g.setColor(Color.red);
for(int i = 1; i < points; i++) {
int x1 = (int)((i - 1) * hstep);
int x2 = (int)(i * hstep);
int y1 = pts[i-1];
int y2 = pts[i];
g.drawLine(x1, y1, x2, y2);
}
}
}

public class SineWave extends JApplet {
SineDraw sines = new SineDraw();
JSlider cycles = new JSlider(1, 30, 5);
public void init() {
Container cp = getContentPane();
cp.add(sines);
cycles.addChangeListener(new ChangeListener(){
public void stateChanged(ChangeEvent e) {
System.out.println( ((JSlider)e.getSource()).getValue());
sines.setCycles( ((JSlider)e.getSource()).getValue());
}
});
cp.add(BorderLayout.SOUTH, cycles);
}
public static void main(String[] args) {
Console.run(new SineWave(), 700, 400);
}
} ///:~