java - 在长 `String`中查找单词的排列

Question

我试图在第二个字符串中找到单词(本例中为“abc”)的所有排列。但我收到了StringOutOFBoundException。代码有什么问题？

public class StringPermutations {

    public static void main(String[] args){

        int count = findPermutations("abc", "Helloabcwwwabcwwqqqqqqaawwbcwwwwabcabc");
        System.out.println("The number of the permutations of abc is " + count);
    }

    public static int findPermutations(String word, String longString){
        int count = 0;
        int length = word.length();

        String myString = "";
        for(int i = 0; i < longString.length() - length; i++){
            if(longString.substring(i, longString.length() - length - i).equals(word)){
                count++;
            }
        }
        return count;
    }
}

Answer 1

在循环中，子字符串的第二个参数有时为负数。您希望它是 longString.substring(i, i + length)