Is there a better way to combine two string sets in java?

java set
FooBar picture FooBar · Jan 30, 2012 · Viewed 82.1k times · Source

I need to combine two string sets while filtering out redundant information, this is the solution I came up with, is there a better way that anyone can suggest? Perhaps something built in that I overlooked? Didn't have any luck with google.

Set<String> oldStringSet = getOldStringSet();
Set<String> newStringSet = getNewStringSet();

for(String currentString : oldStringSet)
{
    if (!newStringSet.contains(currentString))
    {
        newStringSet.add(currentString);
    }
}

Answer

dacwe picture dacwe · Jan 30, 2012

Since a Set does not contain duplicate entries, you can therefore combine the two by:

newStringSet.addAll(oldStringSet);

It does not matter if you add things twice, the set will only contain the element once... e.g it's no need to check using contains method.

Related questions

Convert Set to List without creating new List

I am using this code to convert a Set to a List: Map<String, List<String>> mainMap = new HashMap<>(); for (int i=0; i < something.size(); i++) { Set<String> set = getSet(...); //returns …

Read More
How to Iterate over a Set/HashSet without an Iterator?

How can I iterate over a Set/HashSet without the following? Iterator iter = set.iterator(); while (iter.hasNext()) { System.out.println(iter.next()); }

Read More
How to convert an Array to a Set in Java

I would like to convert an array to a Set in Java. There are some obvious ways of doing this (i.e. with a loop) but I would like something a bit neater, something like: java.util.Arrays.asList(Object[] …

Read More