Question

情景：

我需要从标准输入流中读取一个整数数组，对其进行重新排序，使得素数始终跟随两个偶数，确保从数组中按顺序拾取素数和偶数。它们存在于构建prime-2even集合。任何不能成为该集的一部分的剩余数字都可以按照它们出现的顺序放置在数组的末尾。输入（多行）和预期输出（多行）如下：

输入：

8 5 9 7 8 5 4 6 8

预期输出：

5 8 4 7 6 8 9 5

尝试：

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    int totalElements = Integer.parseInt(scanner.nextLine());

    Integer[] integers = new Integer[totalElements];
    Integer[] primeTwoEvens = new Integer[totalElements];
    Integer[] leftOvers = new Integer[totalElements];

    for (int i = 0; i < integers.length; i++) {
        integers[i] = scanner.nextInt();
    }

    // LOGIC
    int notNullCounter = 0; // Variable to track how many elements of integers array has been set to null.
    while (notNullCounter != integers.length) { // Repeat this process until all the elements of the integers array are null.
        for (int i = 0; i < integers.length; i++) { // Iterate the integers array and check for primeTwoEvens and populate the primeTwoEvens array.
            if (integers[i] != null) { // Is the element of integers array to be processed null? If no, proceed.
                if (isPrime(integers[i])) { // Is the element of integers array prime? If yes, proceed.
                    System.out.println(integers[i] + " is prime..."); // Print statement for debugging purpose.
                    primeTwoEvens[i] = integers[i]; // Since the element of integers array is prime, add it to the primeTwoEvens array.
                    integers[i] = null; // Set this index of integers array to null.
                    notNullCounter++;   // As one element of integers array has been set to null, increment the null counter.


                    int evenCounter = 0; // Variable to track even number occurrences.
                    while (evenCounter != 2) { // Repeat this process until 2 even numbers are not found.
                        for (int j = ++i; j <= integers.length; j++) { // Iterate the remaining elements of integers array and check for next two even numbers.
                            if (isEven(integers[j])) { // Is the element of integers array even? If yes, proceed.
                                System.out.println(integers[j] + " is even..."); // Print statement for debugging purpose.
                                evenCounter++; // Since the element of integers array is even, increment the even counter.
                                primeTwoEvens[++i] = integers[j]; // Since the element of integers array is even, add it to the primeTwoEvens array as well.
                                integers[j] = null; // Set this index of integers array to null.
                                notNullCounter++; // As one element of integers array has been set to null, increment the null counter.
                            }
                        }
                    }
                } /*else { // Element is not prime.

                }*/
            }
        }
        //break;
    }// End of while

    /*System.out.println("@@@@@@@@@@@@ PRINTING THE FINAL SORTED ARRAY  @@@@@@@@@@@@");
    for (Integer integer : integers) {
    System.out.println(integer);
    }*/
}

给我一个java.lang.ArrayIndexOutOfBoundsException

输出：

5 is prime...
8 is even...
4 is even...
6 is even...
8 is even...
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 8
    at Ideone.main(Ideone.java:125)

第125行：

if (isEven(integers[j]))

注意：我只能使用Java标准API和JDK 7。

如何解决问题和最终任务？

Answer 1

我认为前一行（在行125之前）应为

for (int j = ++i; j < integers.length; j++)

不是<=

Answer 2

你可以试试这个：

public static void main(String[] args) {
    // Read your file (I just copy your example to an array)
    Integer[] integers = new Integer[] { 8, 5, 9, 7, 8, 5, 4, 6, 8 };

    List<Integer> prime = new ArrayList<Integer>(), even = new ArrayList<Integer>();
    List<Integer> other = new ArrayList<Integer>(), ordered = new ArrayList<Integer>();

    // Start adding until 1st prime appear
    boolean firstPrime = false;

    for (Integer number : integers) {
        if (isPrime(number)) {
            prime.add(number);
            firstPrime = true;
        } else if (firstPrime && isEven(number)) {
            even.add(number);
        }

        // To have control of the order of appearance
        if (firstPrime) other.add(number);

        // If I have at least 1 prime and 2 even, then add them
        // to my ordered list and remove them from all my other lists
        if(prime.size() >= 1 && even.size() >= 2){
            ordered.add(prime.get(0));
            ordered.add(even.get(0));
            ordered.add(even.get(1));

            other.remove(prime.get(0));
            other.remove(even.get(0));
            other.remove(even.get(1));

            even.remove(1);
            even.remove(0);
            prime.remove(0);
        }
    }

    ordered.addAll(other);

    System.out.println(ordered);
}

如果你运行这个例子，你将有

[5, 8, 4, 7, 6, 8, 9, 5]

排序整数数组时出现java.lang.ArrayIndexOutOfBoundsException

情景：

输入：

预期输出：

尝试：

输出：

第125行：

2 个答案: