You use ->reject() in OCL to return the elements of a collection that do not meet a Boolean condition.

Syntax

collection->reject(iterator | condition)

Part	Meaning
collection	The source collection, also called self in the operator definition.
iterator	A temporary name for each element while the condition is evaluated.
condition	A Boolean expression. Elements for which this expression is true are removed from the returned collection.

The operator signature is:

reject(expr : OclExpression) : Collection(T)

Filter a collection

The following expression starts with four integers and rejects values less than 2:

Set{1, 2, 3, 4}->reject(number | number < 2)

The result contains 2, 3, and 4. The value 1 is excluded because number < 2 evaluates to true for that element.

reject keeps an element when its condition evaluates to false. In this example, 2 < 2 is false, so 2 remains in the result.

Write the condition

Use a condition that evaluates to true for the elements you want to remove. For example, to remove empty text values from a collection of strings, the condition must identify the values considered empty:

texts->reject(text | text = '')

Use the Boolean expressions described in OCL Boolean Operators when you need to combine conditions. For example, a condition can test more than one property of each object.

Result behavior

• The result is a collection of the same element type T as the source collection.
• An element is removed only when the condition is true for that element.
• If no elements meet the condition, the result contains all source elements.
• If every element meets the condition, the result is empty.
• A Set has no duplicate values; use it when you need a literal collection without duplicates.

See also

• Documentation:OCL General Operators
• Documentation:OCL Boolean Operators
• Documentation:OCLOperators Set
• Documentation:OCLOperators forAll