要求：统计文本中出现的单词数，并按数量降序、单词升序输出
在一个名为word.txt中放入

after a minute or two and said to his friend he opened them again
a minute or two and said to
friend he opened them again
and closed and to his

源代码

public static void main(String[] args) throws IOException {StringBuffer sb = readFile();   //读取文本文件中的内容Map<String,Integer> map = getWord(sb);  //取出单词和单词出现的次数存入map中List<Map.Entry<String,Integer>> list = sortValue(map); //根据value对map进行排序for(Map.Entry<String,Integer> entry:list){System.out.println(entry.getKey()+":"+entry.getValue());}}/*** 根据map的value对map进行排序* @param map   key：单词；value：出现的次数* @return      按倒叙方式排好序的list*/private static List<Map.Entry<String, Integer>> sortValue(Map<String, Integer> map) {List<Map.Entry<String,Integer>> list = new ArrayList<>(map.entrySet());/*** Comparator（接口）是匿名内部类，compare是创建匿名内部类要实现的抽象方法* Comparator可看作一个排序器*/Collections.sort(list, new Comparator<Map.Entry<String, Integer>>() {/*** 对list进行排序；o1和o2谁在compareTo之前，谁就从list第一位开始取，在compateTo之后的从第二位开始取* 当o2小于o1时（也就是返回值为-1时），交换o2和o1的位置* @param o1    list从第二位开始取* @param o2    list从第一位开始取* @return      返回0和1时位置不变，返回-1时交换当前o1和o2的位置*/@Overridepublic int compare(Map.Entry<String, Integer> o1, Map.Entry<String, Integer> o2) {return o2.getValue().compareTo(o1.getValue());  //compareTo是Comparable接口的的方法，返回值为1，0，-1}});return list;}/*** 将StringBuffer中的单词单个取出存入map中，单词作为key，出现的次数作为value* @param sb 文本中取出来的内容* @return  将内容中的单词作为key，出现次数作为value存好的map*/private static Map<String, Integer> getWord(StringBuffer sb) {Map<String,Integer> map = new TreeMap<>();//用TreeMap,存入后key就是有序的StringBuffer word = new StringBuffer();/*String word = String.valueOf(new StringBuffer());String[] str = word.split(" ");     //使用split将字符串分隔，" "分隔条件为空格*/for (int i=0;i<sb.length();i++){char c = sb.charAt(i);if(c != ' '){word.append(c);}else {String str = word.toString();if(map.containsKey(str)){Integer value = map.get(str);map.put(str,++value);}else {Integer value = 1;map.put(str,value);}word = new StringBuffer();}}return map;}/*** 从文件中读内容，存入StringBuffer* @return 存好内容的StringBuffer* @throws IOException*/private static StringBuffer readFile() throws IOException {FileReader fis = new FileReader("E:/Code/wordCount/word.txt");BufferedReader br = new BufferedReader(fis);StringBuffer sb = new StringBuffer();String it = br.readLine();while (it != null){sb.append(it);sb.append(" ");it = br.readLine();}return sb;}

运行结果