Java Development
 
Forums: » Register « |  User CP |  Games |  Calendar |  Members |  FAQs |  Sitemap |  Support | 
 
User Name:
Password:
Remember me
 



Go Back   Dev Articles Community ForumsProgrammingJava Development

Reply
Add This Thread To:
  Del.icio.us   Digg   Google   Spurl   Blink   Furl   Simpy   Y! MyWeb 
Thread Tools Search this Thread Display Modes
 
Unread Dev Articles Community Forums Sponsor:
  #1  
Old February 25th, 2004, 08:27 AM
Logwad Logwad is offline
Registered User
Dev Articles Newbie (0 - 499 posts)
 
Join Date: Feb 2004
Posts: 17 Logwad User rank is Just a Lowly Private (1 - 20 Reputation Level) 
Time spent in forums: < 1 sec
Reputation Power: 0
"this" is my new problem

i am having a hard time understanding what "this" does.

// Listen to events from Convert button.
convertTemp.addActionListener(this);

i've been able to ignore it for a while, but i need to be able to know what it does now, the java book i have does not help


this is the entire porgram if you want to look at it
http://java.sun.com/docs/books/tuto...sConverter.java

Reply With Quote
  #2  
Old February 25th, 2004, 10:27 AM
MadCowDzz's Avatar
MadCowDzz MadCowDzz is offline
I'm Internet Famous
Dev Articles Frequenter (2500 - 2999 posts)
 
Join Date: Jan 2003
Location: Toronto, Canada
Posts: 2,886 MadCowDzz User rank is Lance Corporal (50 - 100 Reputation Level)MadCowDzz User rank is Lance Corporal (50 - 100 Reputation Level)MadCowDzz User rank is Lance Corporal (50 - 100 Reputation Level) 
Time spent in forums: 1 Week 16 h 19 m 35 sec
Reputation Power: 18
"this" generally refers to the class that you're calling it from

an easy way to understand it is the fact that you can call instance variables by using this

Code:
public class Hey {
    String whatever;

    // Constructor
    public Hey() {
        this.whatever = "Hey you!";
    }
}


I'll think of a better way to explain this if you need it... =)

Reply With Quote
  #3  
Old February 25th, 2004, 10:43 PM
Logwad Logwad is offline
Registered User
Dev Articles Newbie (0 - 499 posts)
 
Join Date: Feb 2004
Posts: 17 Logwad User rank is Just a Lowly Private (1 - 20 Reputation Level) 
Time spent in forums: < 1 sec
Reputation Power: 0
Ah, so it can be used to shorten the typing needed for calling things inside a class, and maby reduce bugs that may result if you change the class name. that clears up a lot. I was thinking of something very different.

I guess my next problem to look at is to learn how actionlistener works. After that I may be able to figure out what "this" does in the program i'm looking at.

Thanks for the help, and you'll probably hear more from me, because i'm a T.A. in a computer class, and I have to help the teacher try figure out what and how to teach the kids, which involves knowing java better myself -_-

Reply With Quote
  #4  
Old February 26th, 2004, 01:24 AM
merliin's Avatar
merliin merliin is offline
Contributing User
Dev Articles Newbie (0 - 499 posts)
 
Join Date: Feb 2004
Location: Melbourne, Australia
Posts: 30 merliin User rank is Just a Lowly Private (1 - 20 Reputation Level) 
Time spent in forums: < 1 sec
Reputation Power: 14
int main() {
button.addactionlistener(this);
}

int buttonclicked() {
//do stuff
}

Although this is not the corect syntax, it illustrates the idea.
The addactionlistener(this) tells the actioncapable class (such as a button) which class that contorls actions happening to it (such as someone clicking on the button).

Hope that explains it.
(Look at sun's java api for an example with correct syntax that you can copy/paste)

Reply With Quote
Reply

Viewing: Dev Articles Community ForumsProgrammingJava Development > "this" is my new problem


Developer Shed Advertisers and Affiliates


Thread Tools  Search this Thread 
Search this Thread:

Advanced Search
Display Modes  Rate This Thread 
Rate This Thread:


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
View Your Warnings | New Posts | Latest News | Latest Threads | Shoutbox
Forum Jump

Forums: » Register « |  User CP |  Games |  Calendar |  Members |  FAQs |  Sitemap |  Support | 
  
 


Powered by: vBulletin Version 3.0.5
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.

© 2003-2018 by Developer Shed. All rights reserved. DS Cluster - Follow our Sitemap