tips.cloneTest
Class CloneTest

java.lang.Object
  tips.cloneTest.CloneTest

All Implemented Interfaces:

java.lang.Cloneable

public class CloneTest

extends java.lang.Object

implements java.lang.Cloneable

This example demonstrates the use of the clone() method. The default representation of clone() will create a new object without calling any contructors. The attributes of the object will then be copied across to the new object. If in the case of primatives the attributes are copied by value. In the case of objects the references are copied by value. The objects themselves are not copied and the result of clone() will mean that they have two references pointing to them.

Overriding clone allows you to change all that by creating new object and managing the return value yourself.

For example:
The output of this program without overriding clone is:

First Object Age: 10
15/6/2004
Random Number is: 0.659720135566651
First Object Age: 10
12/4/1989
Random Number is: 0.659720135566651
First Object Fred Age: 10
12/4/1989
Random Number is: 0.659720135566651

By uncommenting the clone method we can change the output to:

First Object Age: 10
15/6/2004
Random Number is: 0.5056783284208972
First Object Age: 10
12/4/1989
Random Number is: 0.5056783284208972
MyClone Age: 24
21/3/1961
Random Number is: 0.13724087984367472

Field Summary

private java.util.GregorianCalendar	aDate
private int	age
private RandNum	aRandNum
private java.lang.String	name

Constructor Summary

CloneTest(java.lang.String newLabel)
Constructor that creates an object - with a label

Method Summary

java.lang.Object	clone() Find out what happens when you overload clone.
static void	main(java.lang.String[] args) The main method demonstrating what clone does in this case
(package private) void	print() Prints out the contents of the object on the console
(package private) void	setAge(int age) Set the age to a new value
(package private) void	setDate(int Year, int Month, int Date) Set the date to a new value
java.lang.String	toString() Override toString to printout the label for Debug purposes

Methods inherited from class java.lang.Object

equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

name

private java.lang.String name

age

private int age

aDate

private java.util.GregorianCalendar aDate

aRandNum

private RandNum aRandNum

Constructor Detail

CloneTest

public CloneTest(java.lang.String newLabel)

Constructor that creates an object - with a label

Method Detail

toString

public java.lang.String toString()

Override toString to printout the label for Debug purposes

Returns:

The Label parameter

setDate

void setDate(int Year,
             int Month,
             int Date)

Set the date to a new value

Parameters:

Year - The new year value

Month - The new month value

Date - The daya of the month value

Returns:

void

Throws:

none

setAge

void setAge(int age)

Set the age to a new value

Parameters:

age - The age in years

print

void print()

Prints out the contents of the object on the console

clone

public java.lang.Object clone()

Find out what happens when you overload clone.
This method does not adhere to the:
x.clone().equals(x) == true
rule.

Returns:

Returns a new object

main

public static void main(java.lang.String[] args)
                 throws java.lang.Exception

The main method demonstrating what clone does in this case

Throws:

java.lang.Exception