列出java抛出异常java。lang.IndexOutOfBoundsException：

Question

我正在创建一个程序，它接受一系列数字，并将这些数字的最小对相加。失败的代码如下所示：

import java.util.*;

public class Library {

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        String answer;
        int count;
        int books;
        int writers;
        List<Integer> booksList = new LinkedList<>();
        System.out.printf("Numbers: ");

        answer = input.nextLine();
        String[] arr = answer.split(" ");

        for (String num : arr) {
            booksList.add(Integer.parseInt(num));
        }

        books = booksList.remove(0);
        writers = booksList.remove(0);

        while (booksList.size() > writers) {
            mergeMinimalPair(booksList);
        }
    }

    public static void mergeMinimalPair(List<Integer> books) {  
        int index = 0;
        int minValue = books.get(0) + books.get(1);

        for (int i = 1; i <= books.size() - 1; i++){
            if ((books.get(i) + books.get(i + 1)) < minValue){
                index = i;
                minValue = books.get(i) + books.get(i + 1);
            }
        }
        //combine(books, index, index + 1);
    }

联合方法尚未实现。我使用调试器进行了检查，当调试器即将执行mergeMinimalPair方法时，它抛出以下异常：

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 7, Size: 7
    at java.util.LinkedList.checkElementIndex(LinkedList.java:553)
    at java.util.LinkedList.get(LinkedList.java:474)
    at Library.mergeMinimalPair(Library.java:40)
    at Library.main(Library.java:29)
Java Result: 1

如何避免此异常

Answer 1

问题在于：

for (int i = 1; i <= books.size() - 1; i++){
    if ((books.get(i) + books.get(i + 1)) < minValue){
        index = i;
        minValue = books.get(i) + books.get(i + 1);
    }
}

您正在迭代到books.size() - 1。当i正好等于books.size() - 1时，i + 1等于books.size()，当您执行books.get(i + 1)时，这被认为是超出范围的。修正：

for (int i = 1; i < books.size() - 1; i++){
    if ((books.get(i) + books.get(i + 1)) < minValue){
        index = i;
        minValue = books.get(i) + books.get(i + 1);
    }
}

Answer 2

在代码中

for (int i = 1; i <= books.size() - 1; i++){
    if ((books.get(i) + books.get(i + 1)

i的最大值为book.size() - 1，但对于books.get(i + 1)，此索引太大

最简单的改变是

for (int i = 1; i < books.size() - 1; i++){

Answer 3

循环从1到books.size() - 1，而不是从0到books.size() - 2。在Java中，数组和集合索引总是从0（包含）到大小（排除）