Question

我正在尝试在第二个字符串中找到word（在这种情况下为"abc"）的所有排列。但我得到了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

在你的循环中，substring的第二个参数有时是负数。您希望它为longString.substring(i, i + length)

Answer 2

String.substring方法的参数不能为负数。你应该改变de loop条件。

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

Answer 3

  for(int i = 0; i < longString.length() - length + 1; i++){
        if(longString.substring(i, length + i).equals(word)){
            count++;
        }
  }

循环长度应为longString.length() - length + 1，

和substring (i, length + i)。

在一个长的`String`中找到一个单词的permuatitions

3 个答案: