prekey = key = 2; 
    } 
//'/'操作 
    if (temp == buttonDiv) { 
         switch (prekey) { 
             case 0: 
                 answerd += Double.parseDouble(textAnswer.getText()); 
                 break; 
             case 1: 
                 answerd -= Double.parseDouble(textAnswer.getText()); 
                 break; 
             case 2: 
                 answerd *= Double.parseDouble(textAnswer.getText()); 
                 break; 
             case 3: 
                 if (Double.parseDouble(textAnswer.getText()) == 0) { 
                      textAnswer.setText("除數不能為零"); 
                      clickable = false; 
                 } 
                 else 
                      answerd /= Double.parseDouble(textAnswer.getText()); 
                 break; 
            default: 
                      answerd = Double.parseDouble(textAnswer.getText()); 
         } 
         textAnswer.setText(""); 
         prekey = key = 3; 
      } 
   } 
//'='操作 
   if (temp == buttonEqual && clickable == true) { 
//如果連續按'=',則進行連續運算 
       if (prekey == 5) { 
           if (key == 0) { 
               answerd += vard; 
               textAnswer.setText(df.format(answerd)); 
           } 
           if (key == 1) { 
               answerd -= vard; 
               textAnswer.setText(df.format(answerd)); 
           } 
           if (key == 2) { 
               answerd *= vard; 
               textAnswer.setText(df.format(answerd)); 
           } 
           if (key == 3) { 
               if (Double.parseDouble(textAnswer.getText()) == 0) { 
                    textAnswer.setText("除數不能為零"); 
                    clickable = false; 
               } 
               else { 
                    answerd /= vard; 
                    textAnswer.setText(df.format(answerd)); 
               } 
       } 
    } 
    else { 
         vard = Double.parseDouble(textAnswer.getText()); 
         if (key == 0) { 
              prekey = -1; 
              answerd += Double.parseDouble(textAnswer.getText()); 
              textAnswer.setText(df.format(answerd)); 
         } 
         if (key == 1) { 
              prekey = -1; 
              answerd -= Double.parseDouble(textAnswer.getText()); 
              textAnswer.setText(df.format(answerd)); 
         } 
         if (key == 2) { 
              prekey = -1; 
              answerd *= Double.parseDouble(textAnswer.getText()); 
              textAnswer.setText(df.format(answerd)); 
         } 
         if (key == 3) { 
             prekey = -1; 
             if (Double.parseDouble(textAnswer.getText()) == 0) { 
                  textAnswer.setText("除數不能為零"); 
                  clickable = false; 
             } 
             else { 
                  answerd /= Double.parseDouble(textAnswer.getText()); 
                  textAnswer.setText(df.format(answerd)); 
             } 
         } 
     } 
     prekey = 5; 
  } 
//'%'操作，對第二個操作數除以100 
   if (temp == buttonMod && clickable == true) { 
        if (answerd == 0) { 
             String s = textAnswer.getText(); 
             textAnswer.setText(s); 
        } 
        else { 
             boolean isDot = false; 
             for (int i = 0; i < textAnswer.getText().length(); i++) 
                  if ('.' == textAnswer.getText().charAt(i)) { 
                        isDot = true; 
                        break; 
                  } 
//如果是double數，除100 
             if (isDot == true) { 
                  double dtemp = Double.parseDouble(textAnswer.getText()); 
                  dtemp = dtemp / 100.0; 
                  textAnswer.setText(Double.toString(dtemp)); 
             } 
             else { 
//如果是int數但能被100整除，則去掉末尾兩個零 
                  if (Integer.parseInt(textAnswer.getText()) % 100 == 0) { 
                       int itemp = Integer.parseInt(textAnswer.getText()); 
                       itemp /= 100; 
                       textAnswer.setText(Integer.toString(itemp)); 
                  } 
//如果是int數，但不能被100整除，則按double數處理 
                  else { 
                        double dtemp = Double.parseDouble(textAnswer.getText()); 
                        dtemp = dtemp / 100.0; 
                        textAnswer.setText(Double.toString(dtemp)); 
                  } 
            } 
       } 
    } 
//開根號運算 
    if (temp == buttonSqrt && clickable == true) { 
         String s = textAnswer.getText(); 
         if (s.charAt(0) == '-') { 
              textAnswer.setText("負數不能開根號"); 
              clickable = false; 
         } 
         else 
              textAnswer.setText(Double.toString(java.lang.Math.sqrt(Double. 
         parseDouble(textAnswer.getText())))); 
    }  
//倒數運算 
    if (temp == buttonDao && clickable == true) { 
         if (textAnswer.getText().charAt(0) == '0' && 
              textAnswer.getText().length() == 1) { 
              textAnswer.setText("零不能求倒數"); 
              clickable = false; 
         } 
         else { 
              boolean isDec = true; 
              int i, j, k; 
              String s = Double.toString(1 / Double.parseDouble(textAnswer.getText())); 
              for (i = 0; i < s.length(); i++) 
                    if (s.charAt(i) == '.') 
                         break; 
              for (j = i + 1; j < s.length(); j++) 
                    if (s.charAt(j) != '0') { 
                         isDec = false; 
                    break; 
        } 
        if (isDec == true) { 
             String stemp = ""; 
             for (k = 0; k < i; k++) 
                   stemp += s.charAt(k); 
             textAnswer.setText(stemp); 
        } 
        else 
             textAnswer.setText(s); 
    } 
 } 
//按下'+/-'按鈕時處理 
    if (temp == buttonAddAndSub && clickable == true) { 
         boolean isNumber = true; 
         String s = textAnswer.getText(); 
         for (int i = 0; i < s.length(); i++) 
               if (! (s.charAt(i) >= '0' && s.charAt(i) <= '9' || s.charAt(i) == '.' || 
                      s.charAt(i) == '-')) { 
                    isNumber = false; 
                    break; 
               } 
         if (isNumber == true) { 
//如果當前字符串首字母有'-'號,代表現在是個負數,再按下時,則將首符號去掉 
              if (s.charAt(0) == '-') { 
                   textAnswer.setText(""); 
              for (int i = 1; i < s.length(); i++) { 
                    char a = s.charAt(i); 
                    textAnswer.setText(textAnswer.getText() + a); 
              } 
          } 
//如果當前字符串第一個字符不是符號，則添加一個符號在首字母處 
          else 
              textAnswer.setText('-' + s); 
    } 
    } 
//計算器有關內存操作 
//'MC'的操作，將內存清0 
    if (temp == buttonMC && clickable == true) { 
         memoryd = memoryi = 0; 
         textMemory.setText(""); 
    } 
//'MS'的操作，將當前文本框內容保存入內存，顯示'M' 
    if (temp == buttonMS && clickable == true) { 
         boolean isDot = false; 
         textMemory.setText(" M"); 
         for (int i = 0; i < textAnswer.getText().length(); i++) 
               if ('.' == textAnswer.getText().charAt(i)) { 
                    isDot = true; 
                    break; 
               } 
//如果是double,則存入memoryd(double存儲器) 
         if (isDot == true) { 
              memoryd = Double.parseDouble(textAnswer.getText()); 
              memoryi = 0; //保證存儲器中存放最新的值 
         } 
//如果是int,則存入memoryi(int存儲器) 
         else { 
              memoryi = Integer.parseInt(textAnswer.getText()); 
              memoryd = 0; //保證存儲器中存放最新的值 
         } 
    } 
//'MR'的操作，將存儲器中的信息輸出 
    if (temp == buttonMR && clickable == true) { 
         if (memoryd != 0) 
              textAnswer.setText(Double.toString(memoryd)); 
         if (memoryi != 0) 
              textAnswer.setText(Integer.toString(memoryi)); 
    } 
//'M+'的功能，將當前文本框里的數據和存儲器中數據相加后，再存入存儲器 
    if (temp == buttonMAdd && clickable == true) { 
         boolean isDot = false; 
         for (int i = 0; i < textAnswer.getText().length(); i++) 
               if ('.' == textAnswer.getText().charAt(i)) { 
                     isDot = true; 
                     break; 
               } 
         if (memoryi != 0) { //存儲中是一個int型數 
              if (isDot == false) //被加數是一個int型數 
                   memoryi += Integer.parseInt(textAnswer.getText()); 
              else { //被加數是一個double型數，則將int存儲器中數傳入double存儲器與當前數相加，int存儲器清零 
                   memoryd = memoryi + Double.parseDouble(textAnswer.getText()); 
                   memoryi = 0; 
         } 
    } 
    else 
         memoryd += Double.parseDouble(textAnswer.getText()); 
    } 
//按下'Backspace'鍵，利用循環將當前字符串中的最后一個字母刪除 
    if (temp == buttonBk && clickable == true) { 
         String s = textAnswer.getText(); 
         textAnswer.setText(""); 
         for (int i = 0; i < s.length() - 1; i++) { 
               char a = s.charAt(i); 
               textAnswer.setText(textAnswer.getText() + a); 
         } 
    } 
//按下'CE'按鈕，將當前文本框內數據清除 
    if (temp == buttonCe) { 
         textAnswer.setText(""); 
         clickable = true; 
    } 
//按下'C'按鈕，文本框內數據清除，同時var,answer清0 
    if (temp == buttonC) { 
         vard = answerd = 0; 
         textAnswer.setText(""); 
         clickable = true; 
    } 
//按下'復制'菜單欄 
    if (temp == copyItem) { 
         copy = textAnswer.getText(); 
    } 
//按下'粘貼'菜單欄 
    if (temp == pasteItem) { 
         textAnswer.setText(copy); 
    } 
    if (temp == sItem) { 
         JOptionPane.showMessageDialog(panel, "當前是標準型計算器，\n科學型計算器有待更新。"); 
    } 
//按下'幫助主題'菜單欄 
    if (temp == topHelp) { 
         JOptionPane.showMessageDialog(panel, scrollHelp); 
    } 
//按下'數字分組'菜單欄 
    if (temp == numberGroup) { 
         if (numberGroup.getText().compareTo(" 數字分組(I)") == 0) 
              numberGroup.setText("√數字分組(I)"); 
         else 
              numberGroup.setText(" 數字分組(I)"); 
    } 
//按下'關于'菜單欄 
    if (temp == aboutCal) { 
         JOptionPane.showMessageDialog(panel, "計算器1.00版\n開發者：樓競"); 
    } 
    } 
//輸入中如果有操作非法，比如按下兩次'+'，捕獲異常 
    catch (Exception e) { 
            textAnswer.setText("操作非法"); 
            clickable = false; 
    } 
} 
//主函數 
    public static void main(String args[]) { 
           new Calculator(); 
    } 
}