math.java~5~

Jbuilder100个例子 都是经典例子 对大家学习Jbuilder非常有帮助

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]*40+20;
    }
  }
  public void paint(Graphics g){
    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("图形");
    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("指数");
    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) {

  }
}