net.jini.core.constraint
Class ConstraintAlternatives

java.lang.Object
  net.jini.core.constraint.ConstraintAlternatives

All Implemented Interfaces:

Serializable, InvocationConstraint, RelativeTimeConstraint

public final class ConstraintAlternatives
extends Object
implements RelativeTimeConstraint, Serializable

Combines two or more constraint alternatives into a single overall constraint. The semantics of this aggregate constraint are that at least one of the individual constraint alternatives must be satisfied. The alternatives do not have to be instances of the same type, but they cannot themselves be ConstraintAlternatives instances.

Note that this class implements RelativeTimeConstraint even though the constraint elements might not implement RelativeTimeConstraint.

An instance containing an exhaustive list of alternatives (for example, an instance containing both ClientAuthentication.YES and ClientAuthentication.NO) serves no useful purpose, as a requirement or as a preference. A don't care condition should be expressed by the absence of constraints.

Since:

2.0

Author:

Sun Microsystems, Inc.

See Also:

Serialized Form

Constructor Summary

ConstraintAlternatives(Collection c)
Creates an instance containing the specified alternative constraints, with duplicate constraints removed.

ConstraintAlternatives(InvocationConstraint[] constraints)
Creates an instance containing the specified alternative constraints, with duplicate constraints removed.

Method Summary

static InvocationConstraint	create(Collection c) Returns a constraint representing the specified alternative constraints, with duplicate constraints removed.
static InvocationConstraint	create(InvocationConstraint[] constraints) Returns a constraint representing the specified alternative constraints, with duplicate constraints removed.
Set	elements() Returns an immutable set of all of the constraints.
boolean	equals(Object obj) Two instances of this class are equal if they have the same constraints (ignoring order).
int	hashCode() Returns a hash code value for this object.
InvocationConstraint	makeAbsolute(long baseTime) Returns a constraint equal to the result of taking the constraints in this instance, replacing each constraint that is an instance of RelativeTimeConstraint with the result of invoking that constraint's makeAbsolute method with the specified base time, and invoking the create method of this class with the revised collection of constraints.
String	toString() Returns a string representation of this object.

Methods inherited from class java.lang.Object

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

Constructor Detail

ConstraintAlternatives

public ConstraintAlternatives(InvocationConstraint[] constraints)

Creates an instance containing the specified alternative constraints, with duplicate constraints removed. The argument passed to this constructor is neither modified nor retained; subsequent changes to that argument have no effect on the instance created.

Parameters:

constraints - the alternative constraints

Throws:

NullPointerException - if the argument is null or any element is null

IllegalArgumentException - if any of the elements are instances of ConstraintAlternatives, or if fewer than two elements remain after duplicate constraints are removed

ConstraintAlternatives

public ConstraintAlternatives(Collection c)

Creates an instance containing the specified alternative constraints, with duplicate constraints removed. The argument passed to this constructor is neither modified nor retained; subsequent changes to that argument have no effect on the instance created.

Parameters:

c - the alternative constraints

Throws:

NullPointerException - if the argument is null or any element is null

IllegalArgumentException - if any of the elements are instances of ConstraintAlternatives, or if the elements are not all instances of InvocationConstraint, or if fewer than two elements remain after duplicate constraints are removed

Method Detail

create

public static InvocationConstraint create(InvocationConstraint[] constraints)

Returns a constraint representing the specified alternative constraints, with duplicate constraints removed. If a single constraint remains after duplicates are removed, then that constraint is returned, otherwise an instance of ConstraintAlternatives containing the remaining constraints is returned. The argument passed to this method is neither modified nor retained; subsequent changes to that argument have no effect on the instance created.

Parameters:

constraints - the alternative constraints

Returns:

a constraint representing the specified alternative constraints, with duplicate constraints removed

Throws:

NullPointerException - if the argument is null or any element is null

IllegalArgumentException - if the argument is empty, or if any of the elements are instances of ConstraintAlternatives

create

public static InvocationConstraint create(Collection c)

Returns a constraint representing the specified alternative constraints, with duplicate constraints removed. If a single constraint remains after duplicates are removed, then that constraint is returned, otherwise an instance of ConstraintAlternatives containing the remaining constraints is returned. The argument passed to this method is neither modified nor retained; subsequent changes to that argument have no effect on the instance created.

Parameters:

c - the alternative constraints

Returns:

a constraint representing the specified alternative constraints, with duplicate constraints removed

Throws:

NullPointerException - if the argument is null or any element is null

IllegalArgumentException - if the argument is empty, or if any of the elements are instances of ConstraintAlternatives, or if the elements are not all instances of InvocationConstraint

elements

public Set elements()

Returns an immutable set of all of the constraints. Any attempt to modify this set results in an UnsupportedOperationException being thrown.

Returns:

an immutable set of all of the constraints

makeAbsolute

public InvocationConstraint makeAbsolute(long baseTime)

Returns a constraint equal to the result of taking the constraints in this instance, replacing each constraint that is an instance of RelativeTimeConstraint with the result of invoking that constraint's makeAbsolute method with the specified base time, and invoking the create method of this class with the revised collection of constraints.

Specified by:

makeAbsolute in interface RelativeTimeConstraint

Parameters:

baseTime - an absolute time, specified in milliseconds from midnight, January 1, 1970 UTC

Returns:

a constraint that has the relative times converted to absolute times by adding the specified absolute time to each relative time

hashCode

public int hashCode()

Returns a hash code value for this object.

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Two instances of this class are equal if they have the same constraints (ignoring order).

Overrides:

equals in class Object

toString

public String toString()

Returns a string representation of this object.

Overrides:

toString in class Object