(利用键值对)java中打印集合中字符出现次数

自动拆装箱

import java.util.*; public class BoxingTest { private static final int ONE=1; public BoxingTest() { } public static void main (String[] args) { Map hash=new HashMap(); for(int i=0;i<args.length;i++){ int freq=(Integer)hash.get(args[i])== null ? 0 : (Integer)hash.get(args[i]); hash.put(args[i],freq==0 ? ONE : freq+1); } for(int i=0;i<hash.size();i++){ System.out.println (args[i]+"出现:"+hash.get(args[i])+"次"); } // System.out.println (hash); } }

 

Map 加上泛型

import java.util.*; public class BoxingTest{ private static final int ONE=1; public BoxingTest(){ } public static void main (String[] args) { Map<String,Integer> map=new HashMap<String,Integer>(); for(int i=0;i<args.length;i++){ if(!map.containsKey(args[i])){ map.put(args[i],ONE); } else{ int freq=map.get(args[i]); map.put(args[i],freq+1); } } System.out.println (map.size()+"distinct words detected"); System.out.println (map); } }