找到第一次不重复的字符

public static Character remove(String str) {
	HashMap<Character, Integer> hashMap = new LinkedHashMap<Character, Integer>();
	int i,length;
	Character c;
	length = str.length();
	for(i=0;i<length;i++) {
		c = str.charAt(i);
		//	进行判断
		if(hashMap.containsKey(c)) {
			hashMap.put(c, hashMap.get(c)+1);
		}else {
			hashMap.put(c, 1);
		}
	}
	//	遍历元素，找到第一个不重复并返回
	for(i=0;i<length;i++) {
		c = str.charAt(i);
		if(hashMap.get(c)==1) {
			return c;
		}
	}
	return null;
}