Checking for a not null, not blank String in Java

Question

I am trying to check if a Java String is not null, not empty and not whitespace.

In my mind, this code should have been quite up for the job.

Answer 1

The purpose of the two standard methods is to distinguish between this two cases:

org.apache.common.lang.StringUtils.isBlank(" ") (will return true).

org.apache.common.lang.StringUtils.isEmpty(" ") (will return false).

Your custom implementation of isEmpty() will return true.

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UPDATE:

• org.apache.common.lang.StringUtils.isEmpty() is used to find if the String is length 0 or null.

• org.apache.common.lang.StringUtils.isBlank() takes it a step forward. It not only checks if the String is length 0 or null, but also checks if it is only a whitespace string.

In your case, you're trimming the String in your isEmpty method. The only difference that can occur now can't occur (the case you gives it " ") because you're trimming it (Removing the trailing whitespace - which is in this case is like removing all spaces).