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

Field Summary

Fields

Modifier and Type	Field	Description
(package private) static final AtomicInteger	counter	The number of objects created so far.
(package private) final int	uid	The unique ID for this object.

Constructor Summary

Constructors

Constructor	Description
DeterministicObject()	Create a DeterministicObject.

Method Summary

Modifier and Type	Method	Description
int	hashCode()

Methods inherited from class java.lang.Object

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

Field Details

counter

static final AtomicInteger counter

The number of objects created so far.

uid

final int uid

The unique ID for this object.

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