InputDialogue Joptionpane 有 -1

Question

我的程序工作正常，但是当它打开 JOptionPane.showInputDialog 输入成绩时，框的文本字段中有一个突出显示的 -1。我很无能，搜索结果一无所获。感谢您的宝贵时间！

import javax.swing.JOptionPane;

public class MeanDeviCalc extends javax.swing.JFrame {

//set array size
private double[] gradeArray = new double[25];
//intialize number of grades
private int GradeTotal = 0;

    /**
     * Creates new form MeanDeviCalc
     */
    public MeanDeviCalc() {
        initComponents();
    }

//get function for mean
public double getAverage(double[] gradeArray, int numElem) {
//intialize total with 0
    double total = 0;
    for (int i = 0; i < numElem; i++) 
    {
        //add one for total when grade inputed
        total=total+gradeArray[i];
    }
//divide for mean
    return (total/numElem);
}
//get function for standard deviation
public double getstddev(double[] gradeArray, int numElem, double average) {
//intialize total with 0
    double total = 0;
    for (int i = 0; i < numElem; i++) 
    {
        //standard deviation 
        total = total + Math.pow((gradeArray[i] - average), 2);
    }
    return Math.sqrt(total / numElem);
}

boolean exitloop = false;

do {
    String gradeInput = JOptionPane.showInputDialog(
            "Enter Grade",
            JOptionPane.PLAIN_MESSAGE);

    // When we receive empty/null input, we're done entering grades
    if (gradeInput == null || gradeInput.length() == 0) 
        exitloop=true;
    if(!exitloop){
    double gradeValue = 0; 

    if (GradeTotal == 25) {
        // max array size check
        JOptionPane.showMessageDialog(this,
        "You've already entered the maximum of 25 grades.",
        "Error",
        JOptionPane.ERROR_MESSAGE);
        return; 
    }

    try {
        gradeValue = Double.parseDouble(gradeInput);

    } catch (NumberFormatException e) {
        JOptionPane.showMessageDialog(this,
        "Your input must be numeric!","Bad Data!",JOptionPane.ERROR_MESSAGE);

    }
    // Put grade in the array update total
    gradeArray[GradeTotal] = gradeValue;
    GradeTotal++;
    // Add to grade total
    txtGradeNumber.setText(Integer.toString(GradeTotal));

    double gradeAverage = getAverage(gradeArray, GradeTotal);
    txtMean.setText(Double.toString(gradeAverage));

    double standardDeviation = getstddev(gradeArray, GradeTotal, gradeAverage);
    txtStdDev.setText(Double.toString(standardDeviation));}
} while (GradeTotal < 25 && !exitloop) ;

Answer 1

因为您使用的是 public static String showInputDialog(Component parentComponent, Object message, Object initialSelectionValue) 并且 JOptionPane.PLAIN_MESSAGE 设置为 -1 (public static final int PLAIN_MESSAGE = -1;)

我想你是想使用 public static String showInputDialog(Component parentComponent, Object message, String title, int messageType)

改为

InputDialogue Joptionpane 有 -1

InputDialogue Joptionpane has -1

java

swing

joptionpane