org.apache.commons.collections4.functors

## Class DefaultEquator<T>

- java.lang.Object
- - org.apache.commons.collections4.functors.DefaultEquator<T>

- Type Parameters:
    `T` - the types of object this `Equator` can evaluate.
  All Implemented Interfaces:
    Serializable, Equator<T>

      public class DefaultEquator<T>
      extends Object
      implements Equator<T>, Serializable

  Default `Equator` implementation.
  Since:
    4.0
  Version:
    $Id: DefaultEquator.java 1543950 2013-11-20 21:13:35Z tn $
  See Also:
    Serialized Form

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static int` | `HASHCODE_NULL` Hashcode used for `null` objects.
    `static DefaultEquator` | `INSTANCE` Static instance

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `static <T> DefaultEquator<T>` | `defaultEquator()` Factory returning the typed singleton instance.
    `boolean` | `equate(T o1, T o2)` Evaluates the two arguments for their equality.
    `int` | `hash(T o)` Calculates the hash for the object, based on the method of equality used in the equate method.

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

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

- - ### Field Detail

    - #### INSTANCE

          public static final DefaultEquator INSTANCE

      Static instance

    - #### HASHCODE_NULL

          public static final int HASHCODE_NULL

      Hashcode used for `null` objects.
      See Also:
        Constant Field Values

  - ### Method Detail

    - #### defaultEquator

          public static <T> DefaultEquator<T> defaultEquator()

      Factory returning the typed singleton instance.
      Type Parameters:
        `T` - the object type
      Returns:
        the singleton instance

    - #### equate

          public boolean equate(T o1,
                       T o2)

      Evaluates the two arguments for their equality. Delegates to `Object.equals(Object)`.
      Specified by:
        `equate` in interface `Equator<T>`
      Parameters:
        `o1` - the first object to be equated.
        `o2` - the second object to be equated.
      Returns:
        whether the two objects are equal.

    - #### hash

          public int hash(T o)

      Calculates the hash for the object, based on the method of equality used in the equate method. This is used for classes that delegate their `equals(Object)` method to an Equator (and so must also delegate their `hashCode()` method), or for implementations of `HashedMap` that use an Equator for the key objects.
      Specified by:
        `hash` in interface `Equator<T>`
      Parameters:
        `o` - the object to calculate the hash for.
      Returns:
        `o.hashCode()` if `o` is non- `null`, else `HASHCODE_NULL`.

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