如何对数组进行排序和显示？ [重复]

Question

此问题已经在这里有了答案：

• What causes a java.lang.ArrayIndexOutOfBoundsException and how do I prevent it?25个答案

这是我的代码：包project4;

import java.util.Scanner;

公共类ScoreAnalyzer {

//#OfScores is the length of the scores array
public static int numberOfScores = 0;
public static double[] scores = new double[numberOfScores];
public static double sum = 0.0;
public static double place = 0.0;
//Of sorted list
public static double[] sortedList = new double[numberOfScores];

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    System.out.print("Enter the number of scores you'd like to average: ");
    numberOfScores = input.nextInt();
    scores = new double[numberOfScores];

    for (int count = 0; count < scores.length; count++) {
        System.out.print("Enter score #" + count + ": ");
        place = input.nextDouble();
        scores[count] = place;
        System.out.println("The score of " + scores[count] + " is " + getGrade(count));
    }

    sumOfScores();

    System.out.println("The average of these scores is: " + averageOfScores());

    sort();

    System.out.println("The sorted list of scores (above average scores are "
            + "marked with an\n" + "asterisk '*'): " + sortedList[numberOfScores]);
}

public static char getGrade(int i) {
    //this 
    if (scores[i] >= 90.0) {
        return 'A';
    }
    if (scores[i] >= 80.0) {
        return 'B';
    }
    if (scores[i] >= 70.0) {
        return 'C';
    } 
    if (scores[i] >= 60.0) {
        return 'D';
    } 
    else {
        return 'F';
    }
}

public static double sumOfScores() {
    //sum = 0.0;
    for (int i = 0; i < numberOfScores; i++) {
        sum += scores[i];
    }
    return sum;
}

public static double averageOfScores() {
    double average = sum / numberOfScores;
    return average;
}

public static void sort() {
    for (int i = 0; i < scores.length - 1; i++) {
        // Find the minimum in the list[i..list.length-1]
        double currentMin = scores[i];
        int currentMinIndex;
        currentMinIndex = i;

        for (int j = i + 1; j < scores.length; j++) {
            if (currentMin > scores[j]) {
                currentMin = scores[j];
                currentMinIndex = j;
            }
        }

        // Swap list[i] with list[currentMinIndex] if necessary;
        if (currentMinIndex != i) {
            sortedList[currentMinIndex] = scores[i];
            scores[i] = currentMin;
        }
    }
}

}

该程序的目的是提示用户输入首先要输入的分数，然后允许用户输入该分数。输入每个分数后，程序应为他们输入的每个分数给一个分数。然后，程序应使用一种方法来求和，并将该和传递到一种方法中以求平均值，并对方法中的数组进行排序。应将排序后的数组与平均值一起显示，并且每个高于平均值的分数都应显示注意旁边带有星号。

[运行程序时，我可以输入要平均的分数数量，输入这些分数，获得总和和平均数，但是在对它进行排序以使星号高于平均数时遇到了问题：

输入您想要平均的分数数量：3

输入得分＃0：90

90.0的分数是A

输入得分＃1：80

[80.0分是B

输入得分＃2：70

[70.0分是C

这些分数的平均值是：80.0

线程“主”中的异常java.lang.ArrayIndexOutOfBoundsException：2

at project4.ScoreAnalyzer.sort(ScoreAnalyzer.java:86)

at project4.ScoreAnalyzer.main(ScoreAnalyzer.java:32)

Answer 1

问题出在您的for循环上。由于数组索引以0开头，因此对于大小为3的数组，最高索引将上升为2。但是，按照您的for循环，它的索引将上升为3，这就是ArrayOutOfBoundsException的原因。如下使用它：

for (int count = 0; count < scores.length ; count++)