org.apache.commons.collections.functors

## Class UniquePredicate

- java.lang.Object
- - org.apache.commons.collections.functors.UniquePredicate

- All Implemented Interfaces:
    Serializable, Predicate

      public final class UniquePredicate
      extends Object
      implements Predicate, Serializable

  Predicate implementation that returns true the first time an object is passed into the predicate.
  Since:
    Commons Collections 3.0
  Version:
    $Revision: 646777 $ $Date: 2008-04-10 14:33:15 +0200 (Thu, 10 Apr 2008) $
  Author:
    Stephen Colebourne
  See Also:
    Serialized Form

- - ### Constructor Summary

    Constructors
    Constructor and Description
    `UniquePredicate()` Constructor that performs no validation.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `boolean` | `evaluate(Object object)` Evaluates the predicate returning true if the input object hasn't been received yet.
    `static Predicate` | `getInstance()` Factory to create the predicate.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Constructor Detail

    - #### UniquePredicate

          public UniquePredicate()

      Constructor that performs no validation. Use `getInstance` if you want that.

  - ### Method Detail

    - #### getInstance

          public static Predicate getInstance()

      Factory to create the predicate.
      Returns:
        the predicate
      Throws:
        `IllegalArgumentException` - if the predicate is null

    - #### evaluate

          public boolean evaluate(Object object)

      Evaluates the predicate returning true if the input object hasn't been received yet.
      Specified by:
        `evaluate` in interface `Predicate`
      Parameters:
        `object` - the input object
      Returns:
        true if this is the first time the object is seen

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