Java Array of Templated Classes

Question

i am trying to create this:

Queue<Integer>[] my_var;

When I try to allocate it, intellij gives me this:

my_var = new Queue[4];

Is this Correct? And Also Will I have to innitialize all the elements seperatly?

To be clear what i want is an array of queues

That not the problem. Lets say its Integer or anyother object — Dimitris Karagiannis, May 20 '17 at 13:43
I am not sure What's the equivelant of c++ queue. i want an array containing that kind of objects — Dimitris Karagiannis, May 20 '17 at 13:50
LinkedList is a doubly linked list, which is good for a Queue data structure (FIFO). You can use `LinkedList[]`, but because you're working with generics you should use a `List` of it, possibly `ArrayList`, instead of an array. For example: `ArrayList>` — Unihedron, May 20 '17 at 13:52

score 3 · Accepted Answer · edited May 23 '17 at 12:26

3

To be clear what i want is an array of queues

Please, don't. It has been said multiple times, that arrays and generics don't mix well. You could create an array of Queue using raw types, but don't. Raw types should be avoided in all cases.

Instead, create an List, like

List<Queue<Integer>> m;

You might want to read How to create a generic array?

edited May 23 '17 at 12:26

Community

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answered May 20 '17 at 13:51

dumbPotato21

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I am gonna use your suggestion – Dimitris Karagiannis May 20 '17 at 13:53

Darshan Mehta · Answer 2 · 2017-05-20T13:56:12.613

You need to change a couple of things:

If you are trying to declare Queue of Integer elements then you don't need angular braces ([]) it can just be: Queue<Integer> and not Queue<Integer>[]
Queue is an interface in Java and hence, you can't instantiate it with new. You need to use any of the Implementation of Queue, e.g.:
```
Queue<Integer> my_var;
my_var = new LinkedBlockingQueue<>();
```
And yes, you will have to initialize all the elements separately, or just add the Integers with add method of Queue.

Here are the Queue implementations, you can select any of these depending on your use case.

score 0 · Answer 3 · answered May 20 '17 at 13:45

0

It is right,if you want to create a queue of int, try Queue<Integer> var

answered May 20 '17 at 13:45

dawnfly

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Java Array of Templated Classes

3 Answers3