isNotEmpty

IsNotEmpty is a common predicate in programming that indicates whether a container, sequence, string, or collection contains at least one element. It generally evaluates to true when the length, size, or number of elements is greater than zero, and to false when that measure is zero. In languages with strict null handling, the concept may also involve whether a null input is allowed or treated as empty.

Language-specific usage varies:

- Kotlin: isNotEmpty is an extension method on CharSequence and on collections. For example, list.isNotEmpty() is true when the list has elements; "text".isNotEmpty() is true if the string length is greater than zero. Note that Kotlin also provides isNotBlank to ignore whitespace for strings.

- Java: Libraries such as Apache Commons provide StringUtils.isNotEmpty(str) and CollectionUtils.isNotEmpty(coll), which typically return false if the input is null or has zero length/size.

- Python: There is no universal isNotEmpty function in the standard library. The common pattern is to use bool(x) or len(x) > 0 to test non-emptiness.

- JavaScript: Not built into the language as a single function; practice commonly checks lengths and counts, e.g., array.length > 0 or Object.keys(obj).length > 0 for objects.

Common use cases include input validation, filtering collections, and control flow that should execute only when there is data to process. A related concept is isEmpty, the negation of isNotEmpty, and for strings the distinction between not empty and not blank (the latter ignoring whitespace).

See also: isEmpty, isBlank, notEmpty.