ifexample.java~22~

使用jbuilder开发工具开发的java十个例子代码

package untitled2;

import java.awt.*;
import java.awt.event.*;
import java.applet.*;
import com.borland.jbcl.layout.*;

public class ifexample extends Applet {
  double result;
  boolean isStandalone = false;
  TextField paratext1 = new TextField();
  TextField paratext2 = new TextField();
  TextField paratext3 = new TextField();
  Label label1 = new Label();
  Label label2 = new Label();
  Label label3 = new Label();
  Button button1 = new Button();
  TextField resulttext1 = new TextField();
  XYLayout xYLayout1 = new XYLayout();
  TextField resulttext2 = new TextField();
  Label label4 = new Label();
  Label label5 = 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 ifexample() {
  }
  /**Initialize the applet*/
  public void init() {
    try {
      jbInit();
    }
    catch(Exception e) {
      e.printStackTrace();
    }
  }
  /**Component initialization*/
  private void jbInit() throws Exception {
    paratext1.setFont(new java.awt.Font("Dialog", 0, 16));
    paratext1.setText("0");
    paratext2.setFont(new java.awt.Font("Dialog", 0, 16));
    paratext2.setText("0");
    paratext3.setFont(new java.awt.Font("Dialog", 0, 16));
    paratext3.setText("0");
    label1.setFont(new java.awt.Font("Dialog", 0, 16));
    label1.setText("a");
    label2.setFont(new java.awt.Font("Dialog", 0, 16));
    label2.setText("b");
    label3.setFont(new java.awt.Font("Dialog", 0, 16));
    label3.setText("c");
    button1.setLabel("计算");
    button1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(ActionEvent e) {
        button1_actionPerformed(e);
      }
    });
    resulttext1.setEditable(false);
    resulttext1.setFont(new java.awt.Font("Dialog", 0, 16));
    this.setLayout(xYLayout1);
    resulttext2.setEditable(false);
    resulttext2.setFont(new java.awt.Font("Dialog", 0, 16));
    label4.setFont(new java.awt.Font("Dialog", 0, 16));
    label4.setText("x1=");
    label5.setFont(new java.awt.Font("Dialog", 0, 16));
    label5.setText("x2=");
    this.add(paratext3,    new XYConstraints(120, 100, 70, -1));
    this.add(button1,    new XYConstraints(120, 140, -1, -1));
    this.add(paratext2,     new XYConstraints(120, 70, 70, -1));
    this.add(paratext1,     new XYConstraints(120, 40, 70, -1));
    this.add(label3,   new XYConstraints(100, 100, -1, -1));
    this.add(resulttext1,  new XYConstraints(120, 178, 120, -1));
    this.add(resulttext2,  new XYConstraints(120, 218, 120, -1));
    this.add(label5,    new XYConstraints(70, 218, 46, 27));
    this.add(label4,    new XYConstraints(70, 178, 46, 28));
    this.add(label1,   new XYConstraints(100, 40, -1, -1));
    this.add(label2,   new XYConstraints(100, 70, -1, -1));
  }
  /**Get Applet information*/
  public String getAppletInfo() {
    return "Applet Information";
  }
  /**Get parameter info*/
  public String[][] getParameterInfo() {
    return null;
  }

  void button1_actionPerformed(ActionEvent e) {
      double a1,b1,c1;
      double sqrt;
      double x1,x2;
      try{
         a1 = Double.parseDouble(paratext1.getText());
         b1 = Double.parseDouble(paratext2.getText());
         c1 = Double.parseDouble(paratext3.getText());
         if ((a1 == 0)&&(b1 != 0)){
             x1 = c1/b1;
             resulttext1.setText(String.valueOf(x1));
         }
         if (a1 != 0){
            if ((b1*b1-4*a1*c1)>=0){
              sqrt = getsqrt(a1,b1,c1);
               x1 = ((-1)*b1+sqrt)/(2*a1);
               x2 = ((-1)*b1-sqrt)/(2*a1);
              resulttext1.setText(String.valueOf(x1));
              resulttext2.setText(String.valueOf(x2));
            }
        if ((b1*b1-4*a1*c1)<0){
               sqrt = getsqrt(a1,b1,c1);
               resulttext1.setText(String.valueOf((-1)*b1/(2*a1))+"+"+String.valueOf(sqrt/(2*a1),4)+"i");
               resulttext2.setText(String.valueOf((-1)*b1/(2*a1))+"-"+String.valueOf(sqrt/(2*a1),4)+"i");
            }
          }
      }catch(Exception ex){}
  }
  public double getsqrt(double x,double y,double z){
       result = Math.sqrt(Math.abs(y*y-4*x*z));
       return result;
   }
}