Help with objects in ArrayList

Hi, can someone please help.
I have 4 external classes called Cat, Dog etc.
My test program instantiates them i.e. Cat cat = new Cat();
Afterwards I placed them in an ArrayList called 'animals':

animals.add(cat);
""
"'
""

I then created an enhanced 'for' loop:
The idea is to loop through each object and call its public methods.

for(Obect obj : animals)
{
obj.methodName(); //(The idea is that obj represents 'cat')
}

This creates an error. Is it even possible?
Thanks in advance.

Yes, if you define an "Animal" base class and have them extend that (or interface and have them implement that) and then use that class/interface instead of "Object".

The four external classes in the ArrayList all extend and implement an abstract class called Animal. I cannot create an instance of Animal as it is abstract.

No, but you can reference one. Try it. Change Object to Animal both in the generics definition of the List, and in the for loop.

Quote:

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Originally Posted by BiteMuncher

The four external classes in the ArrayList all extend and implement an abstract class called Animal. I cannot create an instance of Animal as it is abstract.

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Also use a generic List<Animal>; such a list stores animal objects in contrast with a 'raw' List (as you're probably are using now) that stores just Objects.

kind regards,

Jos

I've now got:

for(Animal : animals)
{
System.out.print("This is: "); Animal.describe();
}

Error: incompatible types
required: Animal
found: java.lang.Object

Don't know if I've got this right.

Quote:

---

Originally Posted by JosAH

Also use a generic List<Animal>; such a list stores animal objects in contrast with a 'raw' List (as you're probably are using now) that stores just Objects.

kind regards,

Jos

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Thanks, this seems to have solved it!!

Quote:

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Originally Posted by BiteMuncher

for(Animal : animals)

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Does this even work? It should be something like

Code:

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for(Animal [COLOR="Red"]a[/COLOR]: animals)

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Post the whole code if it's not too much lengthy.

Goldest