找单词问题

找一个特定的单词下面是一个对单词"cat"出现在输入字符串中出现次数进行计数的例子：

import java.util.regex.Matcher;import java.util.regex.Pattern;public class RegexMatches{    private static final String REGEX = "\\bcat\\b";    private static final String INPUT =                                    "cat cat cat cattie cat";    public static void main( String args[] ){       Pattern p = Pattern.compile(REGEX);       Matcher m = p.matcher(INPUT); // 获取 matcher 对象       int count = 0;       while(m.find()) {         count++;         System.out.println("Match number "+count);         System.out.println("start(): "+m.start());         System.out.println("end(): "+m.end());      }   }}

"\\bcat\\b" 是找cat独立的单词，无前后缀
 "\\bcat"找以cat开头的单词
 "cat\\b"找以cat结尾的单词