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Groups > comp.lang.java.programmer > #15175
| From | Eric Sosman <esosman@ieee-dot-org.invalid> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: It doesn't like 'super' where ever I put it. |
| Date | 2012-06-10 11:34 -0400 |
| Organization | A noiseless patient Spider |
| Message-ID | <jr2epp$kja$1@dont-email.me> (permalink) |
| References | <jr27ce$7uo$1@dont-email.me> <jr28la$1dp$1@Gaia.teknon.de> <jr29ot$ltb$1@dont-email.me> |
On 6/10/2012 10:08 AM, bilsch wrote:
> On 6/10/2012 6:49 AM, Volker Borchert wrote:
>> bilsch wrote:
>>> Hello, below is my program stripped to bare bones. Java says 'super'
>>> must be first statement in constructor. I've moved it everywhere still
>>> no luck. The program was running yesterday and I can't figure what
>>> could be wrong. Any suggestions?
>>
>>> public class CalcFrame1 extends JFrame{
>>>
>>> public void CalcFrame1() {
>>
>> This is not a constructor, but a method named like one.
>>
> I'm not exactly clear about constructors. Definitions I've seen are
> vague. Please tell me what I need to add to the program to create a
> proper constructor. Thanks.
Add nothing; *subtract* "void".
A constructor is a special piece of code that initializes a
brand-new object. It looks superficially like a method, and you
can write the same kinds of Java statements in a constructor as
in a method, but it is not a method at all. Among the differences:
- You can call methods, but you cannot "call" constructors.
Constructors run when a `new' operation is performed, to
set up the new object. There are a few operations that
sort of look like "calls" to constructors -- one constructor
can invoke another constructor of the same class with a
this(...) construct, or a constructor of its superclass
with a super(...) -- but as you've seen you cannot just
"call" a constructor the way you'd call toString().
- Methods have names, but constructors don't. If a
constructor throws an exception and a stack trace gets
printed, you'll see something like "ClassName.<init>" as
a sort of stand-in for the name -- but you quite clearly
can't use "<init>" as the name of a method!
- Constructors have no return type, not even `void'. A method
*always* has a return type, even if it's `void'.
I think you need a Java textbook, just like everyone else did
when starting out.
--
Eric Sosman
esosman@ieee-dot-org.invalid
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It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-10 06:27 -0700
Re: It doesn't like 'super' where ever I put it. v_borchert@despammed.com (Volker Borchert) - 2012-06-10 13:49 +0000
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-10 07:08 -0700
Re: It doesn't like 'super' where ever I put it. Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-10 11:34 -0400
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-10 12:58 -0700
Re: It doesn't like 'super' where ever I put it. markspace <-@.> - 2012-06-10 13:43 -0700
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-11 21:01 -0700
Re: It doesn't like 'super' where ever I put it. v_borchert@despammed.com (Volker Borchert) - 2012-06-10 15:44 +0000
Re: It doesn't like 'super' where ever I put it. Robert Klemme <shortcutter@googlemail.com> - 2012-06-10 20:39 +0200
Re: It doesn't like 'super' where ever I put it. "Gavino" <invalid@invalid.invalid> - 2012-06-11 20:13 +0200
Re: It doesn't like 'super' where ever I put it. Robert Klemme <shortcutter@googlemail.com> - 2012-06-11 22:51 +0200
Re: It doesn't like 'super' where ever I put it. "Gavino" <invalid@invalid.invalid> - 2012-06-12 00:45 +0200
Re: It doesn't like 'super' where ever I put it. Martin Gregorie <martin@address-in-sig.invalid> - 2012-06-11 22:53 +0000
Re: It doesn't like 'super' where ever I put it. Lew <lewbloch@gmail.com> - 2012-06-11 16:42 -0700
Re: It doesn't like 'super' where ever I put it. Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-11 19:53 -0400
Re: It doesn't like 'super' where ever I put it. Lew <lewbloch@gmail.com> - 2012-06-11 17:38 -0700
Re: It doesn't like 'super' where ever I put it. "John B. Matthews" <nospam@nospam.invalid> - 2012-06-11 23:14 -0400
Re: It doesn't like 'super' where ever I put it. Robert Klemme <shortcutter@googlemail.com> - 2012-06-12 18:21 +0200
Re: It doesn't like 'super' where ever I put it. Robert Klemme <shortcutter@googlemail.com> - 2012-06-11 22:50 +0200
Re: It doesn't like 'super' where ever I put it. Eric Sosman <esosman@ieee-dot-org.invalid> - 2012-06-10 09:59 -0400
Re: It doesn't like 'super' where ever I put it. Jim Janney <jjanney@shell.xmission.com> - 2012-06-10 08:02 -0600
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-10 07:20 -0700
Re: It doesn't like 'super' where ever I put it. Leif Roar Moldskred <leifm@dimnakorr.com> - 2012-06-10 09:49 -0500
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-10 13:15 -0700
Re: It doesn't like 'super' where ever I put it. Jim Janney <jjanney@shell.xmission.com> - 2012-06-10 10:26 -0600
Re: It doesn't like 'super' where ever I put it. Jim Janney <jjanney@shell.xmission.com> - 2012-06-10 11:24 -0600
Re: It doesn't like 'super' where ever I put it. Jim Janney <jjanney@shell.xmission.com> - 2012-06-10 11:38 -0600
Re: It doesn't like 'super' where ever I put it. v_borchert@despammed.com (Volker Borchert) - 2012-06-10 18:17 +0000
Re: It doesn't like 'super' where ever I put it. Lew <noone@lewscanon.com> - 2012-06-10 12:26 -0700
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-10 13:17 -0700
Re: It doesn't like 'super' where ever I put it. Roedy Green <see_website@mindprod.com.invalid> - 2012-06-10 11:54 -0700
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-10 13:24 -0700
Re: It doesn't like 'super' where ever I put it. Lew <noone@lewscanon.com> - 2012-06-10 13:56 -0700
Re: It doesn't like 'super' where ever I put it. bilsch <bilsch01@gmail.com> - 2012-06-11 20:55 -0700
Re: It doesn't like 'super' where ever I put it. Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-06-11 16:41 -0700
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