A Pay Check Program Write a class PayCheck that uses dialog boxes to compute the total gross pay of an hourly wage worker. The program should use input dialog boxes to get the number of hours worked and the hourly pay rate from the user. The program should use a message dialog to display the total gross pay. The pay calculation should assume the worker earns time and a half for overtime (for hours over 40). 以上是題目 我寫的程式碼 /* PayCheck.java Author : cheng-yuh,wu design a payroll system */ import javax.swing.JOptionPane; public class PayCheck { public static void main (String [] args) { String numStr, result ,st ; int again; double mon,num; double a=40.0; do { numStr = JOptionPane.showInputDialog ("Enter number of hours you work: "); st = JOptionPane.showInputDialog ("Enter your rate per hour : "); num = Double.parseDouble(numStr); mon = Double.parseDouble(st); if (num <=a) { result = "your pay check is " num*mon " dollars"; } else{ result = "your pay check is " (mon*a (num-a)*1.5*mon) " dollars";} JOptionPane.showMessageDialog (null, result); again = JOptionPane.showConfirmDialog (null, "try again?"); } while (again == JOptionPane.YES_OPTION); } } 請各位高手提供意見 如果我想要驗證輸入的是不是數字也就是說只能輸入數字該如何做呢 (exception)

參考拙作: http://delphi.ktop.com.tw/topic.php?TOPIC_ID=50354 末尾第二段有略述 你可以用:

try{
   ...
  double dValue= Double.parseDouble(jtext.getText());
   ...
}catch(java.lang.NumberFormatException nfe){
   //alert一下,user您打錯了.
}
或是:如果你可以取得那個輸入物件的Text Filed的話,直接把事件攔截下來處理
  ....
  Jtext.addKeyListener(new myKeyHandler());
  ...
  ...
  class myKeyHandler extends KeyAdapter{
    public void keyTyped(java.awt.event.KeyEvent e){
        if(e.getKeyChar()=='1'.....){
           //看看一下keyChar是不是介於0~9或是-,".',是的話,不用處理
         }else{
             e.consume();//事件取消(大事化小,小事化無)
         }    
    } 
        
  }

或是實作InputVerifier.verify的方法,請參考 http://java.sun.com/j2se/1.4.2/docs/api/javax/swing/InputVerifier.html

請問try{ ... double dValue= Double.parseDouble(jtext.getText()); ... }catch(java.lang.NumberFormatException nfe){ //alert一下,user您打錯了. } 此 (jtext.getText())中的jtext 代表何物

/* PayCheck.java Author : cheng-yuh,wu design a payroll system */ import javax.swing.JPanel; import java.awt.*; import javax.swing.JOptionPane; import java.io.IOException; public class PayCheck1 { public static void main (String [] args) { String numStr, result ,st ; int again; double mon,num; double a=40.0; do { numStr = JOptionPane.showInputDialog ("Enter number of hours you work: "); st = JOptionPane.showInputDialog ("Enter your rate per hour : "); num = Double.parseDouble(numStr); mon = Double.parseDouble(st); try{ double doubleValue= Double.parseDouble(Jtext.getText()); } catch(java.lang.NumberFormatException nfe){ System.out.println("wrong number"); } if (num <=a) { result = "your pay check is " num*mon " dollars"; } else{ result = "your pay check is " (mon*a (num-a)*1.5*mon) " dollars";} JOptionPane.showMessageDialog (null, result); again = JOptionPane.showConfirmDialog (null, "try again?"); } while (again == JOptionPane.YES_OPTION); } } 可否幫我看看try catch 那裡錯了

請把你的:

   .....
    .....
  num = Double.parseDouble(numStr);
  mon = Double.parseDouble(st);
try{      double doubleValue= Double.parseDouble(Jtext.getText());    }catch(java.lang.NumberFormatException nfe){
   System.out.println("wrong number");
}
   ...
   ...
------------------------------------------------
改成:
  ......
   ......
dobule  num = 0;
double  mon = 0;    try{
  num = Double.parseDouble(numStr);
  mon = Double.parseDouble(st);    }catch(java.lang.NumberFormatException nfe){
   System.out.println("wrong number");
}
   .....

改過後可以complier 和 run 但我試著輸入英文字母 但確沒抓到catch 而是重覆之前run 過的值

對不起 我的意思市說 如何把錯勿訊息秀在對話框給user知道呢 謝謝

try{
   ....
  ....
}catch(java.lang.NumberFormatException nfe){
   //System.out.println("wrong number");
      JOptionPane.showMessageDialog(
        null,"Your Message","Message Title",JOptionPane.WARNING_MESSAGE
      );
 return;
 //or...return the flag of fail,notify system to re-do this process    }

謝謝妳的教導受益良多

請問重那裡給答題者分數啊