• Open Menu Close Menu
  • Apple
  • Shopping Bag
  • Apple
  • Mac
  • iPad
  • iPhone
  • Watch
  • TV
  • Music
  • Support
  • Search apple.com
  • Shopping Bag
 

Lists

Open Menu Close Menu
  • Terms and Conditions
  • Lists hosted on this site
  • Email the Postmaster
  • Tips for posting to public mailing lists
Re: Integer vs. Number vs int
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Integer vs. Number vs int


  • Subject: Re: Integer vs. Number vs int
  • From: Kieran Kelleher <email@hidden>
  • Date: Sat, 29 Nov 2003 00:23:01 -0500

Drew,

If you are beginning Java and want to get off on the right foot with OO programming in Java, I would recommend you go through the following book first:

Beginning Java Objects by Jacquie Barker (available at Amazon or other major online stores)

.......... I have this and the Thinking in Java by Bruce Eckel book that was also recommended to you ..... and for beginners the Beginning Java Objects is an absolutely a great book that can cover a lot of essential fundamentals ground in a short time. It introduces Java basics, then really explains Objected Oriented topics using easy to understand illustrations and finally gets into OO development using Java. The Bruce Eckel book is totally comprehensive but it is a very big book and heavy going for the beginner IMHO .... better as a second book I think.

Also don't forget the Apple "crash course" in Java which is very short and available online at:

http://developer.apple.com/documentation/WebObjects/JavaForWODev/ JavaForWODev.pdf

- K


____________________________________ OS X 10.3.1 / WO 5.2.2 / MySQL 4.0.16


On Nov 27, 2003, at 10:44 AM, Pierre Bernard wrote:

BTW,

there is a major difference between those two lines of code:

public int tempNum = 1;
public String tempString = "abc";

The first one creates a primitive type. The second one creates an object: an instance of java.lang.String. Indeed "abc" is a handy shortcut to create a String object. It might be confusing at first sight as it makes String look like it was a primitive type. But it sure is much more convenient than new String(new char[] { 'a', 'b', 'c' }), isn't it?

Pierre

-----Original Message-----
From: Pierre Bernard
Sent: Thursday, November 27, 2003 4:02 PM
To: Drew Thoeni; email@hidden
Subject: RE: Integer vs. Number vs int


Hi!

The number 1 is an int. int is a primitive type. Other primitive types are: long, double, float, char, boolean, ...

Along those primitive types Java has corresponding wrapper objects that provide a ceratin number of utility methods. The main reason for their existence is for the programmer to be able to handle and store such types the same way as any other Java object. E.g. the only way to store a number in a collection is by wrapping it in such an object. Examples are Integer, Long, Char, Boolean ...

Your variable is a reference to an object of type Number. Number is an abstract superclass of the various wrapper object that represent numbers. You may assign any instance of a concrete subclass of Number to your variable. Integer is such a class. new Integer(1) is a matching object.

For further reading I suggest Bruce Eckel's Thinking in Java. A link to it is available from my web page: http://homepage.mac.com/I_love_my/webobjects.html

Pierre.

-----Original Message-----
From: Drew Thoeni [mailto:email@hidden]
Sent: Thursday, November 27, 2003 12:09 PM
To: email@hidden
Subject: Integer vs. Number vs int


I am trying to put a numeric value into an Number object using:

public Number tempNum = 1;

But I get "incompatible types" on compile.

I'm new to Java but this seems analogous to the Java

public String tempString = "abc";

Which compiles fine.

I get the same "incompatible types" with:

public Integer tempNum = 1;

What am I missing?

Drew
_______________________________________________
webobjects-dev mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev
Do not post admin requests to the list. They will be ignored.



**********************************************************************
This email and any files transmitted with it are intended solely for
the use of the individual or entity to whom they are addressed.
If you have received this email in error please notify the sender
of this message. (email@hidden)
This email message has been checked for the presence of computer
viruses; however this protection does not ensure this message is
virus free.
Banque centrale du Luxembourg; Tel ++352-4774-1; http://www.bcl.lu
**********************************************************************
_______________________________________________
webobjects-dev mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev
Do not post admin requests to the list. They will be ignored.



**********************************************************************
This email and any files transmitted with it are intended solely for
the use of the individual or entity to whom they are addressed.
If you have received this email in error please notify the sender
of this message. (email@hidden)
This email message has been checked for the presence of computer
viruses; however this protection does not ensure this message is
virus free.
Banque centrale du Luxembourg; Tel ++352-4774-1; http://www.bcl.lu
**********************************************************************
_______________________________________________
webobjects-dev mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev
Do not post admin requests to the list. They will be ignored.
_______________________________________________
webobjects-dev mailing list | email@hidden
Help/Unsubscribe/Archives: http://www.lists.apple.com/mailman/listinfo/webobjects-dev
Do not post admin requests to the list. They will be ignored.

  • Prev by Date: Re: Filtering an array of EO objects in D2J (getting the data source)
  • Next by Date: Re: java.lang.OutOfMemoryError during downloads
  • Previous by thread: RE: Integer vs. Number vs int
  • Next by thread: Direct Actions and Sessions
  • Index(es):
    • Date
    • Thread