Understanding Apache Commons Lang StringUtils: isEmpty, isBlank and Related Utility Methods

New developers often confuse the many StringUtils methods provided by Apache Commons Lang; this guide clarifies the purpose and behavior of each method in the isEmpty and isBlank families.

isEmpty series

StringUtils.isEmpty()

Returns true if the CharSequence is null or has length zero; a single space character is considered non‑empty.

StringUtils.isEmpty(null) = true
StringUtils.isEmpty("") = true
StringUtils.isEmpty(" ") = false
StringUtils.isEmpty("bob") = false
StringUtils.isEmpty(" bob ") = false

StringUtils.isNotEmpty()

Simply the negation of isEmpty() .

public static boolean isNotEmpty(final CharSequence cs) {
    return !isEmpty(cs);
}

StringUtils.isAnyEmpty()

Returns true if any of the supplied CharSequences is null or empty.

StringUtils.isAnyEmpty(null) = true
StringUtils.isAnyEmpty(null, "foo") = true
StringUtils.isAnyEmpty("", "bar") = true
StringUtils.isAnyEmpty("bob", "") = true
StringUtils.isAnyEmpty(" bob ", null) = true
StringUtils.isAnyEmpty(" ", "bar") = false
StringUtils.isAnyEmpty("foo", "bar") = false

StringUtils.isNoneEmpty()

Returns true only when all supplied CharSequences are non‑empty (equivalent to !isAnyEmpty(css) ).

public static boolean isNoneEmpty(final CharSequence... css) {
    return !isAnyEmpty(css);
}

isBlank series

StringUtils.isBlank()

Considers null , empty string, or a string consisting solely of whitespace as blank.

StringUtils.isBlank(null) = true
StringUtils.isBlank("") = true
StringUtils.isBlank(" ") = true
StringUtils.isBlank("bob") = false
StringUtils.isBlank(" bob ") = false

StringUtils.isNotBlank()

Negates isBlank() .

public static boolean isNotBlank(final CharSequence cs) {
    return !isBlank(cs);
}

StringUtils.isAnyBlank()

Returns true if any supplied CharSequence is blank (null, empty, or whitespace only).

StringUtils.isAnyBlank(null) = true
StringUtils.isAnyBlank(null, "foo") = true
StringUtils.isAnyBlank(null, null) = true
StringUtils.isAnyBlank("", "bar") = true
StringUtils.isAnyBlank("bob", "") = true
StringUtils.isAnyBlank(" bob ", null) = true
StringUtils.isAnyBlank(" ", "bar") = true
StringUtils.isAnyBlank("foo", "bar") = false

StringUtils.isNoneBlank()

Returns true only when none of the supplied CharSequences are blank.

public static boolean isNoneBlank(final CharSequence... css) {
    return !isAnyBlank(css);
}

Other StringUtils Methods

For a complete list of utilities, refer to the official Apache Commons Lang documentation.

https://commons.apache.org/proper/commons-lang/apidocs/org/apache/commons/lang3/StringUtils.html

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