使用Map集合求出一個字符竄中各個字符的個數

使用Map利用key值的唯一性可以很好的計算出每個key的個數，只要在put之前判斷key是否存在，存在則value+1,否則put（key，1）；注意++value，value++的區別，這是個坑；

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;


public class MapCountString {
	public static void main(String[] args) {
		String str="asdfasdfqwertyuiopasdfghjklzxcvbnm,.dsa.habsdfbasdfkasdnzbxcvlasgdfbasdfb" +
				"khasbdfgahsbdhfhsasdfhjhjsadhfbasddfsasdfasdfasdfasdfasdfxzcvzxcbvbnvbndghjfgjgwertdfgsdf";
		Map<String, Integer> map = MapCountString.map(str);
		@SuppressWarnings("rawtypes")
		Set set = map.entrySet();
		@SuppressWarnings("rawtypes")
		Iterator it =  set.iterator();
		
		while ( it.hasNext()) {
			@SuppressWarnings("unchecked")
			Map.Entry<Character, Integer> entry = (Entry<Character, Integer>) it.next(); 
			System.out.println(entry.getKey()+":"+entry.getValue());
		}
		
	}
	
	public static Map<String,Integer> map(String str){
		str.replace(",", "").replace(".","");
		char[] ch = str.toCharArray();
		
		Map<String,Integer> map = new HashMap<String, Integer>();
		
		String  key = null;
		Integer value = 0;
		for (int i = 0; i < ch.length; i++) {
			key = ch[i]+"";
			if(!map.containsKey(key)){
				map.put(key, 1);
			}else{
				value =map.get(key); 
				map.put(key, ++value);
			}
		}
		
		return map;
	}
}