isBlankCharSequence

isBlankCharSequence is a function name used in various codebases to determine whether a given CharSequence is “blank.” In typical usage, it returns a boolean value: true if the input is null or consists only of whitespace, and false otherwise. It is not part of the standard Java API, but many libraries or projects provide an equivalent utility under this or a similar name.

Definition and behavior

The common definition treats a CharSequence as blank when every character is whitespace, according to Unicode rules. This usually means spaces, tabs, newlines, and other whitespace characters. A null input is often considered blank, as is an empty sequence. If any character is non-whitespace, the function returns false.

Unicode and edge cases

Because whitespace classification is Unicode-aware, the function handles a wide range of whitespace characters beyond the ASCII space. Implementations typically analyze each code unit via Character.isWhitespace. For surrogate pairs or supplementary characters, behavior depends on the specific implementation, but the standard approach evaluates each code point in the sequence for whitespace.

Typical implementations

A common Java implementation uses a straightforward loop:

public static boolean isBlankCharSequence(CharSequence cs) {

if (cs == null) return true;

for (int i = 0; i < cs.length(); i++) {

if (!Character.isWhitespace(cs.charAt(i))) return false;

}

return true;

}

Alternatively, a stream-based approach may be used:

return cs == null || cs.chars().allMatch(Character::isWhitespace);

See also

Java 11 introduced String.isBlank(), but that method applies to String rather than CharSequence. Libraries like Apache Commons Lang offer related utilities such as StringUtils.isBlank(CharSequence).