I want to create an object that will contain and return multiple objects of various types.
What's the best approach for this? There seems to be several ways out there, so I'm interested to hear different peoples' ideas.
Thanks.
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1What do you mean by contain and return? Do you mean it has some function like getObjects()?Zach L– Zach L2011-01-18 08:28:26 +00:00Commented Jan 18, 2011 at 8:28
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Can you please explain more what do you mean by object taht will contain and return ? What do you want to accomplish ?Mihai Toader– Mihai Toader2011-01-18 08:50:50 +00:00Commented Jan 18, 2011 at 8:50
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5 Answers
If you mean to return all of the objects at once, from a single method call, your best bet is to encapsulate all objects into a (possibly inner) class and return an instance of that class.
class Container {
public static class Container {
Type1 obj1;
Type2 obj2;
...
}
private Type1 obj1;
private Type2 obj2;
...
public Container getAllObjects() {
Container container = new Container();
container.obj1 = this.obj1;
...
return container;
}
}
(Technically, you could also return multiple objects within an Object[] array, however I don't recommend this for lack of type safety and open possibilities for making ordering errors.)
If you mean to return the objects one by one, from distinct method calls, good old getters are your friends :-)
class Container {
private Type1 obj1;
private Type2 obj2;
...
public Type1 getObject1() {
return obj1;
}
public Type2 getObject2() {
return obj2;
}
...
}
Comments
Make a class similar to this:
class ReturnValue {
Type1 value1;
Type2 value2;
}
and return an instance if it from your method if you know what types you want to return all the time.
If you don't know then the only way is to return an Object[] containing your values.
Comments
Well there are 3 ways I can see for you:
-1) use the fact that variable passed are passed by reference. this way you can modify directly the object in your function and not have to worry about return values
-2) you can simple create a array of objects:
Object[] returnTab = new Object[numberToStore];
(this is not very pretty I find)
-3) create a ReturnObjectContainer object
public class container { public ObjectA a; public ObjectB b;
Arraylist list = new list();
... //add whatever you need to store }
Comments
What do you mean by "return"? As far as I understand the terms, objects don't return anything, they just are. They can have getters that return an object ofcourse. Could you tell me what several ways you're talking about?
If I understand you correctly you'd just want a class (object) with several private objects (variables) that can be set and gotten trough functions (members).
Comments
Isn't this the definition of all Collection Objects (and most implementations of List interface like ArrayList)?
A collection object contains other objects and return them through a method call?
