java 正则表达式查找某段字符串中所有小写字母开头的单词并统计次数，按出现次数排序

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import java.util.LinkedHashMap;

import java.util.Map;

import java.util.Map.Entry;

import java.util.concurrent.ConcurrentHashMap;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

public class Groups {

    static public final String POEM=

        "Twas brilling,and the slithy toves\n"+

        "Did gyre and gimble in the wabe.\n"+

        "All mimsy were the borogoves,\n"+

        "And the mome raths outgrabe.\n\n"+

        "Beware the Jabberwock,my sin,\n"+

        "The jaws that bite,the claws that catch.\n"+

        "Beware the Jubjub bird,and shun\n"+

        "The frumious Bandersnatch.";

    public static void  main(String[] args){

        Matcher m=

//                Pattern.compile("(?m)(\\S+)\\s+((\\S+)\\s+(\\S+))$").matcher(POEM);//取后三个单词

//                Pattern.compile("\\b[A-Z]\\w+").matcher(POEM);//所有大写单词

//                Pattern.compile("\\b\\p{Upper}\\w+").matcher(POEM);//所有大写单词

//                Pattern.compile("\\b\\p{Lower}\\w+").matcher(POEM);//所有小写单词

                Pattern.compile("\\b[a-z]\\w+").matcher(POEM);//所有小写单词

        Map<String,Integer> strMap=new ConcurrentHashMap<String, Integer>();

        while(m.find()){

            if(strMap.get(m.group())==null)

                strMap.put(m.group(), 1);

            else

                strMap.put(m.group(), strMap.get(m.group())+1);

        }

        strMap=sortMap(strMap);

        for(String danci:strMap.keySet())

            System.out.println(danci+"="+strMap.get(danci));

    }

     public static Map sortMap(Map oldMap) {  

            ArrayList<Map.Entry<Character, Integer>> list = new ArrayList<Map.Entry<Character, Integer>>(oldMap.entrySet());  

            Collections.sort(list, new Comparator<Map.Entry<Character, Integer>>() { 

                public int compare(Entry<java.lang.Character, Integer> arg0,  

                        Entry<java.lang.Character, Integer> arg1) {  

                    return arg1.getValue() - arg0.getValue();  

                }  

            });  

            Map newMap = new LinkedHashMap();  

            for (int i = 0; i < list.size(); i++) {  

                newMap.put(list.get(i).getKey(), list.get(i).getValue());  

            }  

            return newMap;  

      } 

}

运行结果：

the=7

and=3

that=2

slithy=1

bite=1

in=1

frumious=1

catch=1

mome=1

sin=1

mimsy=1

my=1

bird=1

toves=1

shun=1

raths=1

jaws=1

wabe=1

brilling=1

were=1

outgrabe=1

gimble=1

borogoves=1

gyre=1

claws=1