stringisBlank

StringisBlank is a boolean predicate used in programming to determine whether a string should be considered blank. It typically returns true when the input is null, empty, or consists solely of whitespace characters. Some libraries treat null as blank, while others treat null as invalid input and return false or throw an error.

The common definition of blank relies on whitespace classification. Whitespace includes spaces, tabs, newlines, and many Unicode space characters. A string containing any non-whitespace character is not blank. Edge cases may involve non-breaking spaces or special formatting characters, which some implementations classify as whitespace and others do not.

Implementations that resemble StringisBlank appear in many languages, often under different names. In Java, a built-in variant is String.isBlank(), which returns true for empty or whitespace-only strings (and cannot be invoked on null). Apache Commons Lang provides StringUtils.isBlank(CharSequence), which also treats null as blank. Kotlin offers a null-safe variant called isNullOrBlank. In Python, a common pattern is to check whether s is None or s.strip() == "".

Usage considerations include performance and correctness. A robust StringisBlank usually scans characters to detect any non-whitespace without creating unnecessary substrings, or it delegates to optimized library routines. Consistency across languages and libraries is important for predictable behavior, especially regarding null handling and Unicode whitespace.

See also: isEmpty, trim, whitespace, null-safety, String.isBlank, StringUtils.isBlank.