总结:indexOf(String str,int index)方法.从参数指定位置开始,如果index值超过了字符串长度,则返回-1
package com.a.b; import java.io.*; public class Chen { public static void main(String[] args) throws IOException { //线程。继承。抽象 String test="After learning the material"; String theStr="arn"; int index=0,theCount=0; index=test.indexOf(theStr); while(index>=0){ theCount=theCount+1; index=index+theStr.length(); index=test.indexOf("arn",index); } System.out.println(index); // System.out.println("the are "+theCount+" 'arn' in testStr."); } }