Time O(n) Space O(n) Comments and advices are welcome! Thanks!

Products

public long[] products(long[] a){
  	if (a==null || a.length == 0 || a.length == 1) return a;
		long[] ret = new long[a.length];
		long product = 1;
		int zeros = 0;
		int zeropos = 0;
		for (int i = 0; i<a.length;i++){
			if (a[i] == 0){
				zeros++;
				zeropos = i;
			} else 
				product*=a[i];
		}
		if (zeros > 1) return ret;
		if (zeros == 1){
			ret[zeropos] = product;
			return ret;
		}
		for (int i = 0; i<a.length;i++){
			ret[i] = product/a[i];
		}
		return ret;	
	}