HashMap 应用小例子

 

Today, write a little program about HashMap:

 

HashMap is unsyc map, key and value can be null.   Note: the HashMap  traverse function.

 

 

 

import java.util.*;public class CharNum{public static void main(String args[]){ String test="aaabbbbbccccccda"; CharNum cn = new CharNum(); HashMap map = cn.string2map(test); Iterator it = map.entrySet().iterator(); while(it.hasNext()) { Map.Entry entry = (Map.Entry)it.next(); System.out.println(entry.getKey()+": "+entry.getValue()); }}public HashMap string2map(String str){ HashMap<String, Integer> hm = new HashMap<String, Integer>(); String c = null; int var = 0; for(int i =0; i< str.length(); i++) { c = str.substring(i,i+1); if(hm.containsKey(c)) { var = hm.get(c); hm.put(c, ++var); }else { hm.put(c, 1); } } return hm;}}