java 畫sin曲線 java 畫函數曲線

import java.applet.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.Timer;
/*
 * java 畫sin曲線
 */
public class charts extends Applet {

    static int LEN;
    static int Xo, Yo; //座標原點(Xo,Yo)
    static int X2, Y2; //X軸頂點座標(Xo,Yo)
    static final int X1 = 50, Y1 = 30; //Y軸頂點座標(Xo,Yo)
    static int Yunit, Xunit;
    static float Unit;
    static String Xstr, Ystr;  
    static int[] Xval;
    static int[] Yval;
    static float[] Y = new float[5];
    static int Xmax, Xmin;
    static float Ymax, Ymin;
    static int[] Yvalue;
    static int[] Xvalue;
    static float tempy;
    static int here = 0;
    ;
    ActionListener timerActionListener = new ActionListener() {
        public void actionPerformed(ActionEvent evect) {
            Ystr = "";
            here++;
            for (int i = 0 + here; i < 100 + here; i++) {
                Ystr += (int) (Math.sin(Math.PI * i / 25) * 100 + 100) + ",";
            }
            Yvalue = getY(Yunit, tempy, Ymin, Substr(Ystr));
            re();
        }
    };

    public void re() {
        this.repaint();
    }

    public void init() {
        Timer miaobiaoTimer = new Timer(100, timerActionListener);
        miaobiaoTimer.start();
        //setBackground(Color.gray); 
        int width = this.getBounds().width;
        int height = this.getBounds().height;
        setSize(width, height);
        //Xstr = getParameter("xValue");
        Ystr = "100,112,124,136,148,158,168,177,184,190,195,198,199,199,198,195,190,184,177,168,158,148,136,124,112,100,87,75,63,51,41,31,22,15,9,4,1,0,0,1,4,9,15,22,31,41,51,63,75,87,100,112,124,136,148,158,168,177,184,190,195,198,199,199,198,195,190,184,177,168,158,148,136,124,112,100,87,75,63,51,41,31,22,15,9,4,1,0,0,1,4,9,15,22,31,41,51,63,75,87,";
        //Ystr = getParameter("yValue");
        Xstr = "1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50";
        Xval = Substr(Xstr);
        Yval = Substr(Ystr);
        LEN = Xval.length;
        Yvalue = new int[LEN];
        Xvalue = new int[LEN];
        Xo = 50;
        Yo = height - 30;
        X2 = width - 30;
        Y2 = Yo;
        Yunit = (height - 100) / 4;
        Xunit = (width - 100) / LEN;
        Ymax = getMaxVal(Yval);
        Ymin = getMinVal(Yval);
        tempy = ((float) Ymax - (float) Ymin) / 4;
        Y[0] = Ymin; //Y軸座標刻度
        Y[1] = Ymin + tempy;
        Y[2] = Ymin + tempy * 2;
        Y[3] = Ymin + tempy * 3;
        Y[4] = Ymax;
        Unit = (float) (Yunit * 4) / ((float) Ymax - (float) Ymin);
        Yvalue = getY(Yunit, tempy, Ymin, Yval);
    }

    public static int[] getY(int unit, float diff, float ymin, int[] value) {
        int I = 0; //unit=Yunit; diff=temp; ymin=Ymin
        int[] result = new int[LEN];
        for (I = 0; I < LEN; I++) {
            result[I] = (int) (Yo - ((4 * unit) / (diff * 4)) * (value[I] - ymin));
        }
        return result;
    }

    public void paint(Graphics g) {
        g.setColor(Color.red);//座標原點(30,290)
        g.drawLine(Xo, Yo, X1, Y1); //Y軸
        int I;
        for (I = 0; I < 5; I++) {
            g.drawLine(Xo, Yo - Yunit * I, Xo - 5, Yo - Yunit * I); //Y
            g.drawString(Float.toString(Y[I]), Xo - 38, Yo - Yunit * I);
        }
        g.drawLine(X1, Y1, X1 - 5, Y1 + 5); //Y軸左箭頭
        g.drawLine(X1, Y1, X1 + 5, Y1 + 5); //Y軸右箭頭

        g.drawLine(Xo, Yo, X2, Y2); //X軸
        //System.out.PRintln("");
        for (I = 0; I < LEN; I++) {
            g.drawLine(Xo + Xunit * I, Yo, Xo + Xunit * I, Yo + 5); //X
            //System.out.print((Xo+Xunit*I)+" ");
            g.drawString(Integer.toString(Xval[I]), Xo + Xunit * I - 6, Yo + 20);
        }
        g.drawLine(X2, Y2, X2 - 5, Y2 - 5); //X軸左箭頭
        g.drawLine(X2, Y2, X2 - 5, Y2 + 5); //X軸右箭頭

        g.setColor(Color.black);
        g.drawString("Y", X1 - 20, Y1);
        g.drawString("X", X2, Y2 + 20);
        for (I = 0; I < LEN - 1; I++) {
            g.drawLine(Xo + Xunit * I, Yvalue[I], Xo + Xunit * (I + 1), Yvalue[I + 1]);
        }
    }

    public static int[] Substr(String str) {
        int I = 0;
        StringTokenizer st = new StringTokenizer(str, ",");
        int len = st.countTokens();
        int[] val = new int[len];
        while (st.hasMoreTokens()) {
            val[I] = Integer.parseInt(st.nextToken());
            I++;
        }
        return val;
    }

    public static int getMaxVal(int[] Maxval) {
        int I, result;
        result = Maxval[0];
        for (I = 0; I < Maxval.length; I++) {
            if (result < Maxval[I]) {
                result = Maxval[I];
            }
        }
        return result;
    }

    public static int getMinVal(int[] Minval) {
        int I, result;
        result = Minval[0];
        for (I = 0; I < Minval.length; I++) {
            if (result > Minval[I]) {
                result = Minval[I];
            }
        }
        return result;
    }
}