Package org.plumelib.util

Class DeterministicObject

java.lang.Object

org.plumelib.util.DeterministicObject

public class DeterministicObject
extends Object

This is a deterministic version of the Object class. To remove one source of nondeterminism from your program, do not instantiate the Object class, as in new Object(); instead do new DeterministicObject().

This class differs from Object in that it overrides hashCode(). Any use of Object.hashCode() is nondeterministic because the return value of Object.hashCode() depends on when the garbage collector runs. That nondeterminism can affect the iteration order of HashMaps and HashSets, the output of toString(), and other behavior.

To implement similar functionality for other classes, see UniqueId.

See Also:

• UniqueId

Constructor Summary

Constructors

Constructor	Description
DeterministicObject()	Create a DeterministicObject.

Method Summary

Modifier and Type	Method	Description
boolean	equals(@Nullable @GuardSatisfied Object other)	Returns true if this object is the same instance as the given object.
int	hashCode()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

DeterministicObject

public DeterministicObject()

Create a DeterministicObject.

Method Details

hashCode

public int hashCode(@GuardSatisfied DeterministicObject this)

Returns a unique ID for the object. The first object created has the id (and hash code) 0, the second one has 1, and so forth.

Overrides:

hashCode in class Object

equals

public boolean equals(@GuardSatisfied DeterministicObject this,
 @Nullable @GuardSatisfied Object other)

Returns true if this object is the same instance as the given object. Two distinct DeterministicObject objects are never equal.

Overrides:

equals in class Object

Parameters:

other - a value to compare to this

Returns:

true if this is the same as the given object