Sep 9 2011

Remove Multiple Null Values From A List in Java

I’ve had situations where I’ve needed a list of foreign keys (fks) that I get from a result set and from that list make additional queries. Sometimes for whatever reason there are null values in the list and I have to remove them. You might had a similar problem where you needed to remove multiple occurring value from a lists in java. There are a few ways you can approach this problem. You you can remove each occurrence of a list element one at a time. The example below removes any null element in the list one at a time.

while(ids.contains(null)) {
	ids.remove(null);
}

There is another approach you can use to remove all instances of a given value from a list in one go. Instead of the remove method you can use the removeAll as in the following code sample.

ids.removeAll(Collections.singleton(null));

Of course, instead of null values you can remove all instances of any given value from a list based on your business needs.