java练习题获得每个字母出现的次数

package com.webkfa.test;

import java.io.IOException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
public class Test {
	public static void main(String[] args) throws IOException{
		String webkfastr=jscharsum("Adfdafdsafsafdsafdsafdsafdsa");
		System.out.println("运行结果:"+webkfastr);
		//运行结果:f(7)d(7)s(6)A(1)a(7)
	}
	/**
	 * java获得字母出现的次数
	 * @param str
	 * @return a(3)c(2)...
	 */
	public static String jscharsum(String str){
		if(str==null || "".equals(str)){
			return "你传的参数为空";
		}
		StringBuffer sb=new StringBuffer();
		//用java里面的set去重
		Set<String> set=new HashSet<String>();
		for (int i = 0; i < str.length(); i++) {
			char c=str.charAt(i);
			set.add(String.valueOf(c));
		}
		Iterator<String> it =set.iterator();
		while (it.hasNext()) {
			String s =  it.next();
			int csum=0;
			for (int i = 0; i < str.length(); i++) {
				char c=str.charAt(i);
				if(s.equals(String.valueOf(c))){
					csum++;
				}
			}
			sb.append(s+"("+csum+")");
		}
		
		return sb.toString();
	}
}