一个字符串中可能包含a~z中的多个字符，如有重复，如String data = “aavzcadfdafshdjkahskdhaskdhkas”，求出现次数最多的那个字母及次数，如有多个重复的则都求出。

package MonthSep.HWday04;

import MonthSep.TestPackage.Test;

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

public class HW03 {
    public static void main(String[] args) {
        String input = "aajashdkhkuoicxmnasoipfasdjionasudioasu";
        doString(input);
    }
    public static void doString(String input){
        char[] chars = input.toCharArray();
        ArrayList lists = new ArrayList();
        TreeSet set = new TreeSet();
        for(int i = 0; i < chars.length; i++){
            lists.add(String.valueOf(chars[i]));
            set.add(String.valueOf(chars[i]));
        }
        System.out.println(set);
        Collections.sort(lists);
        System.out.println(lists);

        StringBuffer sb = new StringBuffer();
        for(int i = 0; i < lists.size(); i++){
            sb.append(lists.get(i));
        }
        input = sb.toString();
        System.out.println(input);
        int max = 0;
        String maxStr = "";
        ArrayList maxList = new ArrayList();
        Iterator its = set.iterator();
        while (its.hasNext()){
            String os = (String) its.next();
            int begin = input.indexOf(os);
            int end = input.lastIndexOf(os);
            int value = end - begin + 1;
             if(value > max){
                max = value;
                maxStr = os;
                maxList.add(os);
            }else if(max == value){
                maxList.add(os);
            }
        }
        int index = 0;
        for(int i = 0; i < maxList.size(); i++){
            if(maxList.get(i).equals(maxStr)){
                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);
    }
}