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Thomas 11-12-2007 02:27 PM

simple program using interface " iterable"
 
Hello, I have to write a simple program containing a list which would use a
interface iterable or iterate (don't know exaclty whitch one it ). The list
( which would be programmed on my own) would return the iterator, which
would use the standard
methods as hasNext(), remove() and next(). I tried to find some examples
over the internet and the Gosling book " The Java ..." but neither one help
me. I need a simple template which would work or a link where it is
explained.



Lew 11-12-2007 02:38 PM

Re: simple program using interface " iterable"
 
Thomas wrote:
> Hello, I have to write a simple program containing a list which would use a
> interface iterable or iterate (don't know exaclty whitch one it ). The list


Did you mean Iterable, as in java.util.Iterable? (Spelling counts.)

> ( which would be programmed on my own) would return the iterator, which
> would use the standard
> methods as hasNext(), remove() and next(). I tried to find some examples
> over the internet and the Gosling book " The Java ..." but neither one help
> me. I need a simple template which would work or a link where it is
> explained.


If you extend AbstractList you get Iterable for free.

If you simply add "implements Iterable" to your class declaration (they did
cover this in class right? You attended? You took notes?) and implement all
the methods described in Iterable's Javadocs (you do read the Javadocs,
right?), you're home free.

--
Lew

Lew 11-12-2007 02:39 PM

Re: simple program using interface " iterable"
 
Lew wrote:
> Did you mean Iterable, as in java.util.Iterable? (Spelling counts.)


So does the right package name: java.lang.Iterable. Oops.

I got confused with java.util.Iterator.

--
Lew

Thomas 11-13-2007 01:15 AM

Re: simple program using interface " iterable"
 

Użytkownik "Lew" <lew@lewscanon.com> napisał w wiadomo¶ci
news:ke2dnbAItd3--KXanZ2dnUVZ_v7inZ2d@comcast.com...
> Thomas wrote:
>> Hello, I have to write a simple program containing a list which would use
>> a interface iterable or iterate (don't know exaclty whitch one it ). The
>> list

>
> Did you mean Iterable, as in java.util.Iterable? (Spelling counts.)
>
>> ( which would be programmed on my own) would return the iterator, which
>> would use the standard
>> methods as hasNext(), remove() and next(). I tried to find some examples
>> over the internet and the Gosling book " The Java ..." but neither one
>> help me. I need a simple template which would work or a link where it is
>> explained.

>
> If you extend AbstractList you get Iterable for free.
>
> If you simply add "implements Iterable" to your class declaration (they
> did cover this in class right?

Yes I TOOK notes, but this topic wasn't covered and I have to write it on
Thursday before the deadline and have six other
curses so please be less sarcastic.

This template does work :

**********************************

import java.util.Iterator;

public class My_iterator implements Iterator {

public My_iterator(){
}


public boolean hasNext() {
return false;
}

public Object next() {
return new Character('A');
}

public void remove() {

}
}
****************************************

but this doesn't :
***************************************
import java.util.Iterator;
public class ListNode implements java.lang.Iterable {

private String str;
private int count = 0;
public ListNode(){

}

public Iterator iterator(){};
}
*****************************************
since I got:
cannot resolve class Iterator
cannot resolve class Iterable






You attended? You took notes?) and implement all
> the methods described in Iterable's Javadocs (you do read the Javadocs,
> right?), you're home free.
>
> --
> Lew




=?ISO-8859-1?Q?Arne_Vajh=F8j?= 11-13-2007 01:27 AM

Re: simple program using interface " iterable"
 
Thomas wrote:
> but this doesn't :
> ***************************************
> import java.util.Iterator;
> public class ListNode implements java.lang.Iterable {
>
> private String str;
> private int count = 0;
> public ListNode(){
>
> }
>
> public Iterator iterator(){};
> }
> *****************************************
> since I got:
> cannot resolve class Iterator
> cannot resolve class Iterable


I get:

Z.java:10: missing return statement
public Iterator iterator(){};
^
1 error

which seems as very descriptive error message.

Arne

Lew 11-13-2007 02:06 AM

Re: simple program using interface " iterable"
 
Arne VajhĂžj wrote:
> Thomas wrote:
>> but this doesn't :
>> ***************************************
>> import java.util.Iterator;
>> public class ListNode implements java.lang.Iterable {
>>
>> private String str;
>> private int count = 0;
>> public ListNode(){
>>
>> }
>>
>> public Iterator iterator(){};
>> }
>> *****************************************
>> since I got:
>> cannot resolve class Iterator
>> cannot resolve class Iterable

>
> I get:
>
> Z.java:10: missing return statement
> public Iterator iterator(){};
> ^
> 1 error
>
> which seems as very descriptive error message.


That last semicolon has to go, also.

--
Lew

=?UTF-8?B?QXJuZSBWYWpow7hq?= 11-13-2007 02:36 AM

Re: simple program using interface " iterable"
 
Lew wrote:
> That last semicolon has to go, also.


It is not necessary, but it compiles with it.

Arne

Lew 11-13-2007 02:43 AM

Re: simple program using interface " iterable"
 
Arne VajhĂžj wrote:
> Lew wrote:
>> That last semicolon has to go, also.

>
> It is not necessary, but it compiles with it.


Are you saying that it should not go?

If so, why should it stay?

--
Lew

=?UTF-8?B?QXJuZSBWYWpow7hq?= 11-13-2007 03:01 AM

Re: simple program using interface " iterable"
 
Lew wrote:
> Arne VajhĂžj wrote:
>> Lew wrote:
>>> That last semicolon has to go, also.

>>
>> It is not necessary, but it compiles with it.

>
> Are you saying that it should not go?


As stated - it compiles with it.

> If so, why should it stay?


I think the original poster has better things
to spend his time on learning than optional
semicolons or not.

Arne

Lew 11-13-2007 03:36 AM

Re: simple program using interface " iterable"
 
Arne VajhĂžj wrote:
> Lew wrote:
>> Arne VajhĂžj wrote:
>>> Lew wrote:
>>>> That last semicolon has to go, also.
>>>
>>> It is not necessary, but it compiles with it.

>>
>> Are you saying that it should not go?

>
> As stated - it compiles with it.
>
>> If so, why should it stay?

>
> I think the original poster has better things
> to spend his time on learning than optional
> semicolons or not.


Ok.

I think it's a bad idea to put spurious empty constructor lines in strange
places in one's source.

It's a bad habit to start, and the beginning is when it's easiest to form
habits for good or ill.

--
Lew


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