求字符串中指定开始和结束字符串的子串数量

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例如：String s = abababab；String sFrom = a；String sTo = b；那么结果为4；

例如：S = aba; sFrom = ab; sTo = ba；那么结果为1；

例如：S = round; sFrom = ro;sTo = on；那么结果为0。

上代码：

import java.util.Scanner;public class test {public static void main(String[] args) {// TODO Auto-generated method stubScanner sc = new Scanner(System.in);  String s = sc.nextLine(); String sFrom = sc.nextLine();String sTo = sc.nextLine();System.out.println(findNumOfSubstring(s,sFrom,sTo));}public static int findNumOfSubstring(String s,String sFrom,String sTo){if(s == null || s.length() == 0){return 0;}int fromIndex = 0;int toIndex = s.length()-1;int count = 0;while(fromIndex < toIndex){while(s.indexOf(sFrom,fromIndex) == -1 && fromIndex < toIndex){fromIndex++;}            while(s.indexOf(sTo, toIndex) == -1 && fromIndex < toIndex){            toIndex--;            }            if(fromIndex < toIndex){            count++;            }            fromIndex++;            toIndex--;}return count;}}

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