package untitled1;import java.awt.*;import java.awt.event.*;import java.applet.*;import com.borland.jbcl.layout.*;public class math extends Applet {  private double x1[],x2[];  private double y1[],y2[];  boolean isStandalone = false;  XYLayout xYLayout1 = new XYLayout();  Choice choice1 = new Choice();  Label label1 = new Label();  /**Get a parameter value*/  public String getParameter(String key, String def) {    return isStandalone ? System.getProperty(key, def) :      (getParameter(key) != null ? getParameter(key) : def);  }  /**Construct the applet*/  public math() {  }  /**Initialize the applet*/  public void init() {    try {      jbInit();    }    catch(Exception e) {      e.printStackTrace();    }    x1 = new double[360];    y1 = new double[360];    x2 = new double[400];    y2 = new double[400];    for(int i=0;i<360;i++){       x1[i] = 2*Math.PI *i/360;       y1[i] = Math.sin(x1[i]);       x1[i] = x1[i]*20+50;       y1[i] = y1[i]*50+100;    }    for(int i=0;i<400;i++){       x2[i] = -2+0.01*i;       y2[i] = Math.exp(x2[i]);       x2[i] = x2[i]*20+150;       y2[i] = y2[i]*45+20;    }  }  public void paint(Graphics g){    g.clearRect(20,20,300,300);    switch(choice1.getSelectedIndex()){     case 0:       for(int i=0;i<360;i++){          g.drawLine((int)x1[i],(int)y1[i],(int)x1[i+1],(int)y1[i+1]);       }     case 1:       for(int i=0;i<400;i++){          g.drawLine((int)x2[i],(int)y2[i],(int)x2[i+1],(int)y2[i+1]);       }    }  }  /**Component initialization*/  private void jbInit() throws Exception {    this.setLayout(xYLayout1);    label1.setFont(new java.awt.Font("Dialog", 0, 16));    label1.setText("圖形");    choice1.setFont(new java.awt.Font("Dialog", 0, 16));    choice1.addItemListener(new java.awt.event.ItemListener() {      public void itemStateChanged(ItemEvent e) {        choice1_itemStateChanged(e);      }    });    this.add(choice1, new XYConstraints(131, 13, 79, 24));    choice1.addItem("正弦");    choice1.addItem("指數");    this.add(label1,   new XYConstraints(68, 13, 49, 25));  }  /**Get Applet information*/  public String getAppletInfo() {    return "Applet Information";  }  /**Get parameter info*/  public String[][] getParameterInfo() {    return null;  }  void choice1_itemStateChanged(ItemEvent e) {      repaint();  }}