Leetcode First Unique Character in a String JAVA

class Solution {
    public int firstUniqChar(String s) {
        char[] allChar = s.toCharArray();
        Map<Character,Integer> map = new HashMap<>();
        char uniqueChar;
        int answer=-1;
        if(allChar.length==1){
            return 0;
        }
        for(int i=0;i<allChar.length;i++){
            uniqueChar=allChar[i];
            answer = i;
            if(map.get(uniqueChar)!=null){
                answer = -1;
                continue;
            }
            for(int j=i+1;j<allChar.length;j++){
                if(uniqueChar==allChar[j]){
                    map.put(uniqueChar,1);
                    answer=-1;
                    break;
                }
            }
            if(answer!=-1){
                break;
            }
        }
        return answer;
    }
}