com.google.common.base
Interface Equivalence<T>

@Beta
public interface Equivalence<T>

A strategy for determining whether two instances are considered equivalent. Examples of equivalences are the identity equivalence and equals equivalence.

Since:

4

Author:

Bob Lee

equivalent

boolean equivalent(T a,
                   T b)

Returns true if the given objects are considered equivalent.

The equivalent method implements an equivalence relation on non-null object references:

• It is reflexive: for any non-null reference value x, x.equals(x) should return true.
• It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
• It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
• For any non-null reference value x, x.equals(null) should return false.

hash

int hash(T t)

Returns a hash code for object. This function must return the same value for any two instances which are equivalent(T, T), and should as often as possible return a distinct value for instances which are not equivalent.

Throws:

NullPointerException - if t is null

See Also:

the same contractual obligations apply here