优化

CalculatorController.java

@@ -71,9 +71,9 @@ public class CalculatorController {
         }
         String firstNumberText = (firstNumber % 1 == 0) ? String.valueOf((int) firstNumber) : String.valueOf(firstNumber);
         operator = op;
-        currentInput.setLength(0); // 清空当前输入以便输入下一个数字
         isOperationClicked = true;
-        inputField.setText(firstNumberText + " " + operator); // 显示当前操作
+        currentInput.append(operator);
+        inputField.setText(firstNumberText + " " + operator + " "); // 显示当前操作
     }
 
     @FXML
@@ -140,7 +140,6 @@ public class CalculatorController {
         if (currentInput.length() > 0) {
             // 移除最后一个字符
             currentInput.deleteCharAt(currentInput.length() - 1);
-
             // 如果最后一个字符是空格且还有字符，继续删除空格（用于清理运算符后面的空格）
             while (currentInput.length() > 0 && currentInput.charAt(currentInput.length() - 1) == ' ') {
                 currentInput.deleteCharAt(currentInput.length() - 1);