给定一个字符串找出出现次数最多的字符

public static Map getMaxCountChar(String input){
		Map result = new HashMap();
		
		

		char[] charArray = input.toCharArray();
		
		List linkedList = new LinkedList();
		Set treeSet = new TreeSet();
		
		for(int i = 0; i < charArray.length; i++){
			linkedList.add(String.valueOf(charArray[i]));
			treeSet.add(String.valueOf(charArray[i]));
		}
		Collections.sort(linkedList);
		System.out.println("排序后的字符串是：" + linkedList);
		
		StringBuffer sb = new StringBuffer();
		for (String s : linkedList) {
			sb.append(s);
		}
		input = sb.toString();
		
		List maxList = new ArrayList();//存放出现次数比当前次数（即：maxCount）多的字符，有多少存多少，且按字典顺序存放
		int maxCount = 0;//保存出现最多的次数
		String maxString = "";//保存出现次数最多的字符，如果t和y都是出现次数最多的字符则按字典顺序保存t
		
		
		
		Iterator it = treeSet.iterator();
		while(it.hasNext()){
			String temp = it.next();
			int start = input.indexOf(temp);
			int end = input.lastIndexOf(temp);
			int value = end - start + 1;
			if(value > maxCount){
				maxCount = value;
				maxString = temp;
				maxList.add(temp);
			}else if(value == maxCount){
				maxList.add(temp);
			}
		}
		int index = 0;
		for (int i = 0; i < maxList.size(); i++) {
			//如果第i个元素和最先达到最多次数的字符相等那么i之后的所有元素必定也都出现了maxCount次   ①
			if(maxList.get(i).equals(maxString)){
				index = i;
				break;
			}
		}
		
		//由①可知
		for(int i = index; i < maxList.size(); i++){
			System.out.println("出现次数最多的元素是：" + maxList.get(i));
			result.put(maxList.get(i), maxCount);
		}
		
		System.out.println("最多出现的次数是：" + maxCount);
	
		return result;
		
	}