使用“if”、“while”和“loop”方法时出现java非法表达式

Question

我尝试使用“If”和“While”方法，以及这个程序的“loop”，在这个程序中，你可以输入分数，程序计算这些分数的平均值，并给出一个字母值。该程序在计算平均值时运行良好，但当我尝试使用if和while方法生成字母等级时，它开始给出错误，指出clear和close方法的非法表达式。请帮忙。我正在粘贴主方法。错误是指向了接近结尾的清晰和接近的方法

    public static void main(String[] args)
     {
         GradeCalculator application = new GradeCalculator();
         application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     }

        public void enterJButtonActionPerformed(ActionEvent event)
     {
          getAverageGrade();
     }

      public void getAverageGrade()
        {
            scoreAmount = JOptionPane.showInputDialog("Enter Number of scores to be entered?:");
            numberOfScores = Integer.parseInt(scoreAmount);
            getFillupGrades();
        }

      public void getFillupGrades()
       {
         for(counter = 0; counter < numberOfScores; counter++)
       {
         scoreAmount = JOptionPane.showInputDialog("Enter Score:");
         gradeValues = Integer.parseInt(scoreAmount);
         gradeAccumulator += gradeValues;
        }

        calculateAverage();
        }

        public void calculateAverage()
        {
            averageGrade = gradeAccumulator / numberOfScores;

        if (averageGrade > 89)
         {
           averageGradeJTextField.setText("A");

        if (averageGrade > 79)
         {
           averageGradeJTextField.setText("B");

       if (averageGrade > 69)
        {
         averageGradeJTextField.setText("C");

       if (averageGrade > 64)
        {
        averageGradeJTextField.setText("D");
        }
     else
       {
     averageGradeJTextField.setText("F");
        }

      public void clearJButtonActionPerformed(ActionEvent event)
       {
        averageGradeJTextField.setText("");
       }

      public void closeJButtonActionPerformed(ActionEvent event)
      {
         GradeCalculator.this.dispose();
  }
  }

错误状态为：

 ----jGRASP exec: javac -g GradeCalculator.java

GradeCalculator.java:179: error: illegal start of expression
    public void clearJButtonActionPerformed(ActionEvent event)
    ^
GradeCalculator.java:179: error: illegal start of expression
    public void clearJButtonActionPerformed(ActionEvent event)
           ^
GradeCalculator.java:179: error: ';' expected
    public void clearJButtonActionPerformed(ActionEvent event)
                                           ^
GradeCalculator.java:179: error: ';' expected
    public void clearJButtonActionPerformed(ActionEvent event)
                                                             ^
GradeCalculator.java:184: error: illegal start of expression
    public void closeJButtonActionPerformed(ActionEvent event)
    ^
GradeCalculator.java:184: error: illegal start of expression
    public void closeJButtonActionPerformed(ActionEvent event)
           ^
GradeCalculator.java:184: error: ';' expected
    public void closeJButtonActionPerformed(ActionEvent event)
                                           ^
GradeCalculator.java:184: error: ';' expected
    public void closeJButtonActionPerformed(ActionEvent event)
                                                             ^
GradeCalculator.java:188: error: reached end of file while parsing
}
 ^
9 errors

Answer 1

您打开了许多if块，但没有关闭它们（代码正确缩进）：

public void calculateAverage() {
    averageGrade = gradeAccumulator / numberOfScores;
    if (averageGrade > 89) {
        averageGradeJTextField.setText("A");

        if (averageGrade > 79) {
            averageGradeJTextField.setText("B");

            if (averageGrade > 69) {
                averageGradeJTextField.setText("C");

                if (averageGrade > 64) {
                    averageGradeJTextField.setText("D");
                }
                else {
                    averageGradeJTextField.setText("F");
                }

按如下方式更改该方法（包括缺少大括号并使用else if而不是if）：

public void calculateAverage() {
    averageGrade = gradeAccumulator / numberOfScores;
    if (averageGrade > 89) {
        averageGradeJTextField.setText("A");
    } // was missing
    else if (averageGrade > 79) {
        averageGradeJTextField.setText("B");
    } // was missing
    else if (averageGrade > 69) {
        averageGradeJTextField.setText("C");
    } // was missing
    else if (averageGrade > 64) {
        averageGradeJTextField.setText("D");
    } // was missing
    else {
        averageGradeJTextField.setText("F");
    } // was missing
}