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Let's say I have a class like this:

public class Kern_Pair {
int letter1, letter2;

}

Can someone tell me how the default equals function will behave?

like

kernpair1.equals(kernpair2)

?

On 8/9/2012 5:58 PM, bob smith wrote:
> Let's say I have a class like this:
>
> public class Kern_Pair {
> int letter1, letter2;
>
> }
>
> Can someone tell me how the default equals function will behave?
>
> like
>
> kernpair1.equals(kernpair2)
>
> ?

Teachable Moment.

The Kern_Pair class has no equals() method of its own, so it
inherits equals() from the nearest superclass that has one. Walk
up the class inheritance tree to find the nearest ancestor with an
equals(). The class inheritance tree for Kern_Pair is fairly short:
Its immediate superclass is Object (because you didn't say "extends
SomethingElse"), so the equals() method for Kern_Pair *is* the
equals() method of Object.

Now all you need to do is go to the Javadoc and study what
Object's equals() will do.

--
Eric Sosman
d

On 08/09/2012 05:58 PM, bob smith wrote:
> Let's say I have a class like this:
>
> public class Kern_Pair {
> int letter1, letter2;
>
> }
>
> Can someone tell me how the default equals function will behave?
>
> like
>
> kernpair1.equals(kernpair2)
>
> ?
<http://docs.oracle.com/javase/tutorial/java/IandI/objectclass.html>
Here is a convenient dashboard to the Oracle Java documentation.
<http://docs.oracle.com/javase/7/docs/>
You may replace the 7 in the above address with a 3, 4, 5 or 6
to see older versions documentation.

On Thursday, August 9, 2012 5:11:07 PM UTC-5, Eric Sosman wrote:
> On 8/9/2012 5:58 PM, bob smith wrote:
>
> > Let's say I have a class like this:
>
> >
>
> > public class Kern_Pair {
>
> > int letter1, letter2;
>
> >
>
> > }
>
> >
>
> > Can someone tell me how the default equals function will behave?
>
> >
>
> > like
>
> >
>
> > kernpair1.equals(kernpair2)
>
> >
>
> > ?
>
>
>
> Teachable Moment.
>
>
>
> The Kern_Pair class has no equals() method of its own, so it
>
> inherits equals() from the nearest superclass that has one. Walk
>
> up the class inheritance tree to find the nearest ancestor with an
>
> equals(). The class inheritance tree for Kern_Pair is fairly short:
>
> Its immediate superclass is Object (because you didn't say "extends
>
> SomethingElse"), so the equals() method for Kern_Pair *is* the
>
> equals() method of Object.
>
>
>
> Now all you need to do is go to the Javadoc and study what
>
> Object's equals() will do.
>
>
>
> --
>
> Eric Sosman
>
> d

The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

On 8/10/2012 10:12 AM, bob smith wrote:
> On Thursday, August 9, 2012 5:11:07 PM UTC-5, Eric Sosman wrote:
>> On 8/9/2012 5:58 PM, bob smith wrote:
>>> [...]
>>> Can someone tell me how the default equals function will behave?
>> [...]
>> Now all you need to do is go to the Javadoc and study what
>> Object's equals() will do.
>
> The equals method for class Object implements the most discriminating possible equivalence relation on objects; that is, for any non-null reference values x and y, this method returns true if and only if x and y refer to the same object (x == y has the value true).

... and there you have it. Any questions?

--
Eric Sosman
d

On 8/9/2012 6:22 PM, Jeff Higgins wrote:
> Here is a convenient dashboard to the Oracle Java documentation.
> <http://docs.oracle.com/javase/7/docs/>
> You may replace the 7 in the above address with a 3, 4, 5 or 6
> to see older versions documentation.

And surprising that works (via redirect).

Surprisingly because Java SE 3 and 4 are J2SE 1.3 and 1.4!

Someone at Oracle has been smart.

Arne