统计字符串中出现次数最多的字母的次数，如果有多个重复的，都求出

package javastudy;

import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.TreeSet;

public class Test1 {
	public static void main(String [] args){
		String str = "aacdggdhrdhgsjrsovoiwimtcpiq";
		new Test1().doString(str) ;
	}
	public void doString (String str){
		char [] chars = str.toCharArray() ;
		ArrayList<String> lists = new ArrayList<String>() ;
		TreeSet<String> set = new TreeSet<String>();
		for (int i=0;i<chars.length;i++){
			lists.add(String.valueOf(chars[i]));
			set.add(String.valueOf(chars[i]));
		}
		//有序且无重复,找到所有出现的
		System.out.println("set:"+set); 
		//有序可以有重复，arraylist可以快速排序 
		Collections.sort(lists) ;       
		System.out.println("lists:"+lists) ;
		
		//得到排序后的字符串
		StringBuffer sb = new StringBuffer() ;
		for (int i=0;i<lists.size();i++){
			sb.append(lists.get(i)) ;
		}
		str = sb.toString();
		System.out.println("str after sorted:"+str) ;
		
		//统计了第一个出现最多的char的次数 ，记下出现最多的次数 为max,对应的char为maxString
		int max =0;
		String maxString ="";
		ArrayList<String> maxList = new ArrayList<String>();
		Iterator itr = set.iterator() ;
		while (itr.hasNext()) {
			String os= (String)itr.next() ;
			int begin = str.indexOf(os) ;
			int end = str.lastIndexOf(os) ;
			int value = end-begin+1;
			if (value>max){
				max= value ;
				maxString = os ;
				maxList.add(os) ;
			}else if (value == max) {
				maxList.add(os); 
			}
		}
		
		//找到最大的位置
		int index = 0;
		for (int i=0;i<maxList.size();i++){
			if (maxList.get(i).equals(maxString)){
				index =i;
				break ;
			}
		}
		System.out.println("max data");
		for (int i=index;i<maxList.size();i++){
			System.out.println(maxList.get(i)+"");
		}
		System.out.println() ;
		System.out.println("max:"+ max) ;
		
	}
}

输出结果为

set:[a, c, d, g, h, i, j, m, o, p, q, r, s, t, v, w]
lists:[a, a, c, c, d, d, d, g, g, g, h, h, i, i, i, j, m, o, o, p, q, r, r, s, s, t, v, w]
str after sorted:aaccdddggghhiiijmoopqrrsstvw
max data
d
g
i