Menu
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() .add(val1).add(val2).add(val3).add(val4).toString(); ...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)?
815
Using the String.concat() method is a good choice when we want to concatenate String objects. The empty String returned by the getNonNullString() method gets concatenated to the result, thus ignoring the null objects.
When SET CONCAT_NULL_YIELDS_NULL is ON, concatenating a null value with a string yields a NULL result. For example, SELECT 'abc' + NULL yields NULL . When SET CONCAT_NULL_YIELDS_NULL is OFF, concatenating a null value with a string yields the string itself (the null value is treated as an empty string).
To concatenate null to a string, use the + operator.
There are two ways to concatenate strings in Java: By + (String concatenation) operator. By concat() method.
String joined = Stream.of(val1, val2, val3, val4) .filter(s -> s != null && !s.isEmpty()) .collect(Collectors.joining(",")); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
