String isNullOrEmpty in Java? [duplicate]

• StringUtils.isEmpty(str) or StringUtils.isNotEmpty(str)
• StringUtils.isBlank(str) or StringUtils.isNotBlank(str)

from Apache commons-lang.

The difference between empty and blank is : a string consisted of whitespaces only is blank but isn’t empty.

I generally prefer using apache-commons if possible, instead of writing my own utility methods, although that is also plausible for simple ones like these.