How do I check that a Java String is not all whitespaces?
I would use the Apache Commons Lang library. It has a class called StringUtils that is useful for all sorts of String operations. For checking if a String is not all whitespaces, you can use the following:
StringUtils.isBlank(<your string>)
Here is the reference: StringUtils.isBlank
StringUtils.isBlank(CharSequence)
https://commons.apache.org/proper/commons-lang/javadocs/api-release/org/apache/commons/lang3/StringUtils.html#isBlank-java.lang.CharSequence-
Slightly shorter than what was mentioned by Carl Smotricz:
!string.trim().isEmpty();
Shortest solution I can think of:
if (string.trim().length() > 0) ...
This only checks for (non) white space. If you want to check for particular character classes, you need to use the mighty match()
with a regexp such as:
if (string.matches(".*\\w.*")) ...
...which checks for at least one (ASCII) alphanumeric character.