freq.java

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import java.util.*;

public class Freq {
 
     public static void main(String args[]) {
        String[] words={"if","it","is", "to", "be", "it", "is", "up", 
        					"to", "me", "to", "delegate"};
        Integer freq ;
        Map m = new TreeMap();

        // 构造字符串数组words的单词频率表.以单词为key,以词频为value。
        for (int i=0; i<words.length; i++) {
        	freq = (Integer) m.get(words[i]); //获取指定单词的词频。
        	
 			//词频递增
            if (freq==null){
            	freq = new Integer(1);
            }else{
            	freq = new Integer(freq.intValue() + 1);
            }
            m.put(words[i], freq); //在Map中更改词频。
        }

        System.out.println(m.size() + " distinct words detected:");
        System.out.println(m);
    }
}