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super object reference

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  super object reference Philipp Kraus <philipp.kraus@flashpixx.de> - 2015-01-31 19:02 +0100
    Re: super object reference Jeff Higgins <jeff@invalid.invalid> - 2015-01-31 13:14 -0500
    Re: super object reference Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2015-01-31 22:47 -0800
      Re: super object reference Philipp Kraus <philipp.kraus@flashpixx.de> - 2015-02-01 12:40 +0100
        Re: super object reference Arne Vajhøj <arne@vajhoej.dk> - 2015-02-01 09:13 -0500
          Re: super object reference Arne Vajhøj <arne@vajhoej.dk> - 2015-02-01 09:21 -0500
            Re: super object reference Philipp Kraus <philipp.kraus@flashpixx.de> - 2015-02-01 23:44 +0100
        Re: super object reference Jeff Higgins <jeff@invalid.invalid> - 2015-02-01 09:23 -0500
          Re: super object reference Arne Vajhøj <arne@vajhoej.dk> - 2015-02-01 09:30 -0500
        Re: super object reference Kevin McMurtrie <mcmurtrie@pixelmemory.us> - 2015-02-02 19:46 -0800
    Re: super object reference Roedy Green <see_website@mindprod.com.invalid> - 2015-02-05 04:37 -0800

#30964 — super object reference

Hello,

I have got this class structure:

clas parent
{
     int value = 5;
}

class child extends parent
{

   public doit()
   {
          Object x = this.super; **
   }

}

I would like to get at ** a reference to the super object of my class, 
I need a reference to the full object not to particular methods and 
properties.
How can I do this?

Thanks a lot

Phil

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#30965

On 01/31/2015 01:02 PM, Philipp Kraus wrote:
> Hello,
>
> I have got this class structure:
>
> clas parent
> {
>      int value = 5;
> }
>
> class child extends parent
> {
>
>    public doit()
>    {
>           Object x = this.super; **
>    }
>
> }
>
> I would like to get at ** a reference to the super object of my class, I
> need a reference to the full object not to particular methods and
> properties.
> How can I do this?
>
this is a reference to the full object
there is no "super object" only a super class

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#30978

In article <maj5b2$1fos$1@ariadne.rz.tu-clausthal.de>,
 Philipp Kraus <philipp.kraus@flashpixx.de> wrote:

> Hello,
> 
> I have got this class structure:
> 
> clas parent
> {
>      int value = 5;
> }
> 
> class child extends parent
> {
> 
>    public doit()
>    {
>           Object x = this.super; **
>    }
> 
> }
> 
> I would like to get at ** a reference to the super object of my class, 
> I need a reference to the full object not to particular methods and 
> properties.
> How can I do this?
> 
> Thanks a lot
> 
> Phil


You have two classes but only one instance object.  There is no parent 
instance.

For proper design, a child class must not contradict the declared API of 
the parent class.  There's refactoring needed if it does.  For example, 
LinkedHashMap does not behave in any way that contradicts the declared 
API of HashMap.

Maybe you're thinking of inner/outer classes?  An outer class is 
OuterClassName.this.

-- 
I will not see posts from astraweb, theremailer, dizum, or google
because they host Usenet flooders.

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#30980

On 2015-02-01 06:47:00 +0000, Kevin McMurtrie said:

> In article <maj5b2$1fos$1@ariadne.rz.tu-clausthal.de>,
>  Philipp Kraus <philipp.kraus@flashpixx.de> wrote:
> 
>> Hello,
>> 
>> I have got this class structure:
>> 
>> clas parent
>> {
>> int value = 5;
>> }
>> 
>> class child extends parent
>> {
>> 
>> public doit()
>> {
>> Object x = this.super; **
>> }
>> 
>> }
>> 
>> I would like to get at ** a reference to the super object of my class,
>> I need a reference to the full object not to particular methods and
>> properties.
>> How can I do this?
>> 
>> Thanks a lot
>> 
>> Phil
> 
> 
> You have two classes but only one instance object.  There is no parent
> instance.
> 
> For proper design, a child class must not contradict the declared API of
> the parent class.  There's refactoring needed if it does.  For example,
> LinkedHashMap does not behave in any way that contradicts the declared
> API of HashMap.
> 
> Maybe you're thinking of inner/outer classes?  An outer class is
> OuterClassName.this.

I see this is a conceptional design error at my code. I use my variable x
within a deeper framewok call and this call runs 
x.getclass.getDecalredFields(), but
this returns in the example case nothing, ebcause my child class does 
not have any fields.

I have got only the x reference but I need all fields of the object, 
also the fields of the child & parent
class and fields of the parent-parent class... I would like to create a 
field list from my object x over all
fields that are exists within the objects. IMHO I must run from my 
object class up to the java.object and collect all fields.
How can I do this?

Phil

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#30981

On 2/1/2015 6:40 AM, Philipp Kraus wrote:
> I see this is a conceptional design error at my code. I use my variable x
> within a deeper framewok call and this call runs
> x.getclass.getDecalredFields(), but
> this returns in the example case nothing, ebcause my child class does
> not have any fields.
>
> I have got only the x reference but I need all fields of the object,
> also the fields of the child & parent
> class and fields of the parent-parent class... I would like to create a
> field list from my object x over all
> fields that are exists within the objects. IMHO I must run from my
> object class up to the java.object and collect all fields.
> How can I do this?

You recurse.

First getDeclaredFields() and then getSuperclass() and process that.

Arne

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#30982

On 2/1/2015 9:13 AM, Arne Vajhøj wrote:
> On 2/1/2015 6:40 AM, Philipp Kraus wrote:
>> I see this is a conceptional design error at my code. I use my variable x
>> within a deeper framewok call and this call runs
>> x.getclass.getDecalredFields(), but
>> this returns in the example case nothing, ebcause my child class does
>> not have any fields.
>>
>> I have got only the x reference but I need all fields of the object,
>> also the fields of the child & parent
>> class and fields of the parent-parent class... I would like to create a
>> field list from my object x over all
>> fields that are exists within the objects. IMHO I must run from my
>> object class up to the java.object and collect all fields.
>> How can I do this?
>
> You recurse.
>
> First getDeclaredFields() and then getSuperclass() and process that.

Demo:

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.List;

public class AllFields {
	private static void analyze(Class<?> clz, List<Field> fields) {
		for(Field f : clz.getDeclaredFields()) fields.add(f);
		if(!clz.getSuperclass().equals(Object.class)) 
analyze(clz.getSuperclass(), fields);
	}
	public static void dump(Object o) {
		System.out.println(o.getClass().getName());
		List<Field> fields = new ArrayList<>();
		analyze(o.getClass(), fields);
		for(Field f : fields) {
			System.out.println("  " + f.getName());
		}
	}
	public static void main(String[] args) {
		dump(new A());
		dump(new B());
		dump(new C());
	}
}

class A {
	private Object a;
}

class B extends A {
	private Object b;
}

class C extends B {
	private Object c;
}

Arne

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#30991

Gerate, thanks for all the help.

Phil

On 2015-02-01 14:21:04 +0000, Arne Vajhøj said:

> On 2/1/2015 9:13 AM, Arne Vajhøj wrote:
>> On 2/1/2015 6:40 AM, Philipp Kraus wrote:
>>> I see this is a conceptional design error at my code. I use my variable x
>>> within a deeper framewok call and this call runs
>>> x.getclass.getDecalredFields(), but
>>> this returns in the example case nothing, ebcause my child class does
>>> not have any fields.
>>> 
>>> I have got only the x reference but I need all fields of the object,
>>> also the fields of the child & parent
>>> class and fields of the parent-parent class... I would like to create a
>>> field list from my object x over all
>>> fields that are exists within the objects. IMHO I must run from my
>>> object class up to the java.object and collect all fields.
>>> How can I do this?
>> 
>> You recurse.
>> 
>> First getDeclaredFields() and then getSuperclass() and process that.
> 
> Demo:
> 
> import java.lang.reflect.Field;
> import java.util.ArrayList;
> import java.util.List;
> 
> public class AllFields {
> 	private static void analyze(Class<?> clz, List<Field> fields) {
> 		for(Field f : clz.getDeclaredFields()) fields.add(f);
> 		if(!clz.getSuperclass().equals(Object.class)) 
> analyze(clz.getSuperclass(), fields);
> 	}
> 	public static void dump(Object o) {
> 		System.out.println(o.getClass().getName());
> 		List<Field> fields = new ArrayList<>();
> 		analyze(o.getClass(), fields);
> 		for(Field f : fields) {
> 			System.out.println("  " + f.getName());
> 		}
> 	}
> 	public static void main(String[] args) {
> 		dump(new A());
> 		dump(new B());
> 		dump(new C());
> 	}
> }
> 
> class A {
> 	private Object a;
> }
> 
> class B extends A {
> 	private Object b;
> }
> 
> class C extends B {
> 	private Object c;
> }
> 
> Arne

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#30984

On 02/01/2015 06:40 AM, Philipp Kraus wrote:
>
> I see this is a conceptional design error at my code. I use my variable x
> within a deeper framewok call and this call runs
> x.getclass.getDecalredFields(), but
> this returns in the example case nothing, ebcause my child class does
> not have any fields.
>
> I have got only the x reference but I need all fields of the object,
> also the fields of the child & parent
> class and fields of the parent-parent class... I would like to create a
> field list from my object x over all
> fields that are exists within the objects. IMHO I must run from my
> object class up to the java.object and collect all fields.
> How can I do this?
>
<https://github.com/ronmamo/reflections>
ReflectionUtils.getAllFields(...)
get all fields of given type,
up the super class hierarchy,
optionally filtered by predicates

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#30985

On 2/1/2015 9:23 AM, Jeff Higgins wrote:
> On 02/01/2015 06:40 AM, Philipp Kraus wrote:
>> I see this is a conceptional design error at my code. I use my variable x
>> within a deeper framewok call and this call runs
>> x.getclass.getDecalredFields(), but
>> this returns in the example case nothing, ebcause my child class does
>> not have any fields.
>>
>> I have got only the x reference but I need all fields of the object,
>> also the fields of the child & parent
>> class and fields of the parent-parent class... I would like to create a
>> field list from my object x over all
>> fields that are exists within the objects. IMHO I must run from my
>> object class up to the java.object and collect all fields.
>> How can I do this?
>>
> <https://github.com/ronmamo/reflections>
> ReflectionUtils.getAllFields(...)
> get all fields of given type,
> up the super class hierarchy,
> optionally filtered by predicates

It may be a very useful library that can do a lot of interesting
stuff, but an external library seems a bit overkill for something
as simple as this.

Arne

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#31026

In article <mal3bb$20i5$1@ariadne.rz.tu-clausthal.de>,
 Philipp Kraus <philipp.kraus@flashpixx.de> wrote:

> On 2015-02-01 06:47:00 +0000, Kevin McMurtrie said:
> 
> > In article <maj5b2$1fos$1@ariadne.rz.tu-clausthal.de>,
> >  Philipp Kraus <philipp.kraus@flashpixx.de> wrote:
> > 
> >> Hello,
> >> 
> >> I have got this class structure:
> >> 
> >> clas parent
> >> {
> >> int value = 5;
> >> }
> >> 
> >> class child extends parent
> >> {
> >> 
> >> public doit()
> >> {
> >> Object x = this.super; **
> >> }
> >> 
> >> }
> >> 
> >> I would like to get at ** a reference to the super object of my class,
> >> I need a reference to the full object not to particular methods and
> >> properties.
> >> How can I do this?
> >> 
> >> Thanks a lot
> >> 
> >> Phil
> > 
> > 
> > You have two classes but only one instance object.  There is no parent
> > instance.
> > 
> > For proper design, a child class must not contradict the declared API of
> > the parent class.  There's refactoring needed if it does.  For example,
> > LinkedHashMap does not behave in any way that contradicts the declared
> > API of HashMap.
> > 
> > Maybe you're thinking of inner/outer classes?  An outer class is
> > OuterClassName.this.
> 
> I see this is a conceptional design error at my code. I use my variable x
> within a deeper framewok call and this call runs 
> x.getclass.getDecalredFields(), but
> this returns in the example case nothing, ebcause my child class does 
> not have any fields.
> 
> I have got only the x reference but I need all fields of the object, 
> also the fields of the child & parent
> class and fields of the parent-parent class... I would like to create a 
> field list from my object x over all
> fields that are exists within the objects. IMHO I must run from my 
> object class up to the java.object and collect all fields.
> How can I do this?
> 
> Phil

Use getFields() for use within a subclass to self-inspect.

The inspectors like getMethods() return references that don't work for 
public methods of a protected class.  For that, call 
getDeclaredMethods() on the public class/interface that originally 
declared them.  This is commonly a problem with anonymous inner classes 
implementing a public interface.  The result of 
someAnonObject.getClass().getMethods() is of little use.

-- 
I will not see posts from astraweb, theremailer, dizum, or google
because they host Usenet flooders.

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#31050

On Sat, 31 Jan 2015 19:02:14 +0100, Philipp Kraus
<philipp.kraus@flashpixx.de> wrote, quoted or indirectly quoted
someone who said :

>Hello,
>
>I have got this class structure:
>
>clas parent
>{
>     int value = 5;
>}
>
>class child extends parent
>{
>
>   public doit()
>   {
>          Object x = this.super; **
>   }
>
>}
>
>I would like to get at ** a reference to the super object of my class, 
>I need a reference to the full object not to particular methods and 
>properties.
>How can I do this?
>
>Thanks a lot
>
>Phil

When you have a child object, in a single chunk of RAM with both child
and parent fields. So for all practical purposes is already is a
parent object. If you want a stripped down object, you need to build
in field by field. I asked Sun a long time about ways to make this
efficient, but they said I was the only one interested.

I wanted to efficiently convert Dog -> Dalmatian and Dalmatians -> Dog
objects because I only exported the "Dog" fields to the outside world.

-- 
Roedy Green Canadian Mind Products http://mindprod.com
To solve an interesting problem, start by finding a problem
that is interesting to you.
~ Eric S. Raymond (born: 1957-12-04 age: 57)

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