数组中重复的数字---java版做的么啥意思

   public boolean duplicate(int numbers[],int length,int [] duplication) {
         if (numbers==null||numbers.length<2){
            return false;
        }
        Map<Integer,Integer> map=new HashMap<>();
        for(int i=0;i<=numbers.length-1;i++){
            map.put(numbers[i],map.get(numbers[i])==null?1:map.get(numbers[i])+1);
        }
        for(int i=0;i<numbers.length-1;i++){
            if (map.get(numbers[i])>1){
                duplication[0]=numbers[i];
                return true;
            }
        }
        return false;
    }