org.jmock.expectation
Class Null

java.lang.Object
  org.jmock.expectation.Null

public class Null
extends Object

A class that represents the null value. The Null class is used when an Expectation is set to expect nothing.

Example usage:

 public class MockX {
    private Expectation... anExpectation = new Expectation...(...);
 

    public MockX() {
       anExpectation.setExpectNothing();
    }
 

    public void setAnExpectation(Object value) {
       anExpectation.setExpected(value);
    }
 

    public void setActual(Object value) {
       anExpectation.setActual(value);
    }
 }
 

The act of calling Expectation.setExpectNothing() tells the expectation that it should expect no values to change. Since all Null objects are equal to themselves, most expectations set their expected value to an instance of Null, and at the same time, set their actual value to another instance of Null. This way, when org.jmock.expectation.Verifiable#verify() checks expectations, they will compare two Null objects together, which is guaranteed to succeed.

Version:

$Id: Null.java,v 1.1 2007/04/06 13:51:54 npryce Exp $

Author:

Francois Beausoleil (fbos@users.sourceforge.net)

Field Summary

static String	DEFAULT_DESCRIPTION The default description for all Null objects.
static Null	NULL A default Null object.

Constructor Summary

Null()
Instantiates a new Null object with the default description.

Null(String description)
Instantiates a new Null object and sets it's description.

Method Summary

boolean	equals(Object other) Determines equality between two objects.
int	hashCode() Returns this Null object's hashCode.
String	toString() Returns a string representation of this Null object.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_DESCRIPTION

public static final String DEFAULT_DESCRIPTION

The default description for all Null objects. This String is equal to "Null".

See Also:

Constant Field Values

NULL

public static final Null NULL

A default Null object. Instead of always instantiating new Null objects, consider using a reference to this object instead. This way, the virtual machine will not be taking the time required to instantiate an object everytime it is required.

Constructor Detail

Null

public Null()

Instantiates a new Null object with the default description.

See Also:

DEFAULT_DESCRIPTION

Null

public Null(String description)

Instantiates a new Null object and sets it's description.

Parameters:

description -

Method Detail

equals

public boolean equals(Object other)

Determines equality between two objects. Null objects are only equal to another instance of themselves.

Overrides:

equals in class Object

Parameters:

other -

hashCode

public int hashCode()

Returns this Null object's hashCode. All Null return the same hashCode value.

Overrides:

hashCode in class Object

toString

public String toString()

Returns a string representation of this Null object. This merely returns the string passed to the constructor initially.

Overrides:

toString in class Object