GUI_对四则运算案例加入校验和提示

怼烎@ 2022-06-18 12:44 95阅读 0赞

private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {                                         
            //获取第一个操作数
            String firstNumberString = this.firstNumber.getText().trim();
            //获取运算符
            String selectOperator = this.selectOperator.getSelectedItem().toString();
            //获取第二个操作数
            String secondNumberString = this.secondNumber.getText().trim();
    
            //校验第一个操作数
            String regex = "\\d+";
            if (!firstNumberString.matches(regex)) {
                JOptionPane.showMessageDialog(this, "第一个操作数不满足要求必须是数字!");
                this.firstNumber.setText("");
                this.firstNumber.requestFocus();
                return;//回去吧
            }
    
            //样验第二个操作数
            if (!secondNumberString.matches(regex)) {
                JOptionPane.showMessageDialog(this, "第二个操作不满足要求必须是数字!");
                this.secondNumber.setText("");
                this.secondNumber.requestFocus();
                return;//回去吧
            }
    
            //把字符串转换成整数
            int firstNumber = Integer.parseInt(firstNumberString);
            int secondNumber = Integer.parseInt(secondNumberString);
    
            //定义变量接收结果
            int resultNumber = 0;
    
            switch (selectOperator) {
                case "+":
                    resultNumber = firstNumber + secondNumber;
                    break;
                case "-":
                    resultNumber = firstNumber - secondNumber;
                    break;
                case "*":
                    resultNumber = firstNumber * secondNumber;
                    break;
                case "/":
                    resultNumber = firstNumber / secondNumber;
                    break;
            }
    
            //把结果赋值给结果框
            this.resultNumber.setText(String.valueOf(resultNumber));
        }