Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.java.programmer > #15177

Re: It doesn't like 'super' where ever I put it.

Show key headers only | View raw

bilsch <bilsch01@gmail.com> writes:

> On 6/10/2012 7:02 AM, Jim Janney wrote:
>> bilsch<bilsch01@gmail.com>  writes:
>>> BUILD SUCCESSFUL (total time: 2 seconds)
>>
>> Try changing
>>
>>      public void CalcFrame1() {
>>
>> to
>>
>>      public CalcFrame1() {
>>
> OK.  Thanks.  Can you tell me why that makes a difference?

Constructors are fundamentally different from ordinary methods, so most
object-oriented languages use a different syntax for them.  In Java, a
constructor definition looks like a method, but without an explicit
return type and using a name that matches the class name.  In other
languages the syntax may be different -- for example, in Python the name
is always __init__ -- but the underlying idea is the same: constructors
are not ordinary methods and take a different syntax.

Why are constructors different?  Most classes have some code that you
want to run whenever a new object is created, and it would be tedious to
have to call it explicitly every time.  I used to mimic OOP in C and you
had to do things like

    struct Foo* foo = (struct Foo*) malloc(sizeof(struct Foo));
    foo->init();

Forcing all object creation to go through a constructor makes the code
simpler and more reliable.  And even when a class has a constructor that
appears to be empty, there's still some code that the compiler generates
automatically the make the new object a proper instance of its class.

-- 
Jim Janney

Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

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

csiph-web