获取itcast字符串在整个字符串中出现的次数

"gzitcastabcgzabcitcastabcjavaabcandroiditcast"

public class TestReadStringItcast

{

public static void main(String[] args) {

  String a = "gzitcastabcgzabcitcastabcjavaabcandroiditcast";

  String b = "itcast";

  System.out.println(getSubNum(a, b));

}

public static int getSubNum(String a, String b) {

  int num = 0;

  String str = a;

  int index = a.indexOf(b);

  while (index != -1) {

   num++;

   str = str.substring(index + b.length() - 1);

   index = str.indexOf(b);

  }

  return num;

}

}

输出：出现次数:3

str=str.substring(index+b.length()-1);
index=str.indexOf(b);


代码改成这样一句。   整个方法 用  indexOf就行了
index = str.indexOf(b,index+b.length());

多谢兄弟指点