我的if塊有什麼問題？

Question

我的計劃中的一切工作除此之外的工作。我看不出有什麼問題。如果用戶輸入超過25個等級，我需要該程序吐出一條錯誤消息。這裏是我的代碼

package my.meancalculator; 

import javax.swing.JOptionPane; 
import javax.swing.JFrame; 
import java.text.DecimalFormat; 


public class MeanCalcUI extends javax.swing.JFrame { 

private final DecimalFormat formatter = new DecimalFormat("#0.0"); 
private double gradeAverage; 
private double standardDeviation; 
JFrame frame = new JFrame(); 
private double[] gradeArray = new double[25]; 
private int numberOfGradesInput = 0; 


public MeanCalcUI() { 
    initComponents(); 
    setLocationRelativeTo(null); 
} 

public double getAverage(double[] gradeArray, int numberOfGradesInput) { 

    double sum = 0; 

    for (int i = 0; i < numberOfGradesInput; i++) { 
     sum = sum + gradeArray[i]; 
    } 

    return (sum/numberOfGradesInput); 
} 

public double getStdDev(double[] gradeArray, int numberOfGradesInput, double average) { 

    double sum = 0; 

    for (int i = 0; i < numberOfGradesInput; i++) { 
     sum = sum + Math.pow((gradeArray[i] - average), 2); 
    } 

    return Math.sqrt(sum/numberOfGradesInput); 
} 


private void btnExitActionPerformed(java.awt.event.ActionEvent evt) {           
    System.exit(0); 
}          

private void btnEnterGradesActionPerformed(java.awt.event.ActionEvent evt) {            

    if (numberOfGradesInput > 25) { 
     // We've already finished entering the max # of grades 
     JOptionPane.showMessageDialog(frame, 
       "You can only input 25 grades!", 
       "Too much data!", 
       JOptionPane.ERROR_MESSAGE); 
     return;   
    } 
    do { 
     String gradeInput = JOptionPane.showInputDialog(frame, 
       "Enter Grade", 
       "Enter Grade", 
       JOptionPane.PLAIN_MESSAGE); 

     // When we receive empty/null input, we're done entering grades 
     if (gradeInput == null || gradeInput.length() == 0) { 
      break; 
     } 

     double gradeValue = 0; // Set to avoid 'may be unset' compiler error 
     try { 
      gradeValue = Double.parseDouble(gradeInput); 
     } catch (NumberFormatException e) { 
      JOptionPane.showMessageDialog(frame, 
        "Your input must be numeric!", 
        "Bad Data!", 
        JOptionPane.ERROR_MESSAGE); 
      continue; // start over again 
     } 

     // Put the grade into the array and update the number of grades entered 
     gradeArray[numberOfGradesInput] = gradeValue; 
     numberOfGradesInput++; 

     // Add to the grade total 
     txtNumGrades.setText(formatter.format(numberOfGradesInput)); 

     //use the getAverage method to get the average of the grades 
     gradeAverage = getAverage(gradeArray, numberOfGradesInput); 
     txtMean.setText(formatter.format(gradeAverage)); 

     //use the getStdDev method to get the standard deviation 
     standardDeviation = getStdDev(gradeArray, numberOfGradesInput, gradeAverage); 
     txtStdDeviation.setText(formatter.format(standardDeviation)); 
    } while (numberOfGradesInput < 25); 



} 

我用我的整個代碼，以防萬一它是如果這是造成這種情況。每次運行程序時，我都會輸入一個超過25倍的窗口號，並要求用戶輸入關閉，並且不會彈出錯誤消息。有什麼我在這裏做錯了嗎？

Answer 1

我認爲你需要改變你的條件>=，爲您做/而25分的成績要求，之後你的病情仍然會是假的，你會再次進入循環，將獲得出界異常

if (numberOfGradesInput >= 25) 

Answer 2

認爲你需要改變你的條件> =，爲您做/而25分的成績要求，之後你的病情仍然會是假的，你會再次進入循環，將獲得出界異常

if (numberOfGradesInput >= 25) 

當您的按鈕操作被觸發它應該檢查它是否大於或等於25.在你的if語句和你的while循環之間你有一個沒有被覆蓋的用例。

如果等級數爲25，該怎麼辦？用你編寫的代碼將跳過你的if語句，並輸入你的do-while循環並添加「26年級」（實際上會導致IndexOutOfBoundsException而不是打印出錯誤對話框）

Answer 3

問題出在您的病情，做一段時間。我試圖做最少的修改代碼，使其工作。

 do { 
      if (numberOfGradesInput >= 25) { 
       // We've already finished entering the max # of grades 
       JOptionPane.showMessageDialog(frame, 
         "You can only input 25 grades!", 
         "Too much data!", 
         JOptionPane.ERROR_MESSAGE); 
       return; 
      } 
      else{ 
       //.... 
      } 
     } while (numberOfGradesInput < 26);