eze eze - 2 years ago 219
Java Question

Concatenate string values with delimiter handling null and empty strings in java 8?

In Java 8 I have some number of String values and I want to end up with a comma delimited list of valid values. If a String is null or empty I want to ignore it. I know this seems common and is a lot like this old question; however, that discussion does not address nulls AND spaces (I also don't like the accepted answer).

I've looked at Java 8 StringJoiner, commons StringUtils (join) and trusty guava (Joiner) but none seems like a full solution. The vision:

where: val1="a", val2=null, val3="", val4="b"

String niceString = StringJoiner.use(",").ignoreBlanks().ignoreNulls()

would result in niceString = "a,b"

Isn't there a nice way to do this (that doesn't involve for loops, loading strings into a list, and/or regex replaces to remove bad entries)?

Answer Source
String joined = 
    Stream.of(val1, val2, val3, val4)
          .filter(s -> s != null && !s.isEmpty())
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