Creating a new ArrayList in Java

Question

Assuming that I have a class named Class,

And I would like to make a new ArrayList that it\'s values will be of type Class.

My question

Answer 1

You're very close. Use same type on both sides, and include ().

ArrayList<Class> myArray = new ArrayList<Class>();

Answer 2

You are looking for Java generics

List<MyClass> list = new ArrayList<MyClass>();

Here's a tutorial http://docs.oracle.com/javase/tutorial/java/generics/index.html

Answer 3

Java 8

In order to create a non-empty list of fixed size where different operations like add, remove, etc won't be supported:

List<Integer> fixesSizeList= Arrays.asList(1, 2);

Non-empty mutable list:

List<Integer> mutableList = new ArrayList<>(Arrays.asList(3, 4));

Java 9

With Java 9 you can use the List.of(...) static factory method:

List<Integer> immutableList = List.of(1, 2);

List<Integer> mutableList = new ArrayList<>(List.of(3, 4));

Java 10

With Java 10 you can use the Local Variable Type Inference:

var list1 = List.of(1, 2);

var list2 = new ArrayList<>(List.of(3, 4));

var list3 = new ArrayList<String>();

Check out more ArrayList examples here.

Answer 4

If you just want a list:

ArrayList<Class> myList = new ArrayList<Class>();

If you want an arraylist of a certain length (in this case size 10):

List<Class> myList = new ArrayList<Class>(10);

If you want to program against the interfaces (better for abstractions reasons):

List<Class> myList = new ArrayList<Class>();

Programming against interfaces is considered better because it's more abstract. You can change your Arraylist with a different list implementation (like a LinkedList) and the rest of your application doesn't need any changes.

Answer 5

Do this: List<Class> myArray= new ArrayList<Class>();

Answer 6

    ArrayList<Class> myArray = new ArrayList<Class>();

Here ArrayList of the particular Class will be made. In general one can have any datatype like int,char, string or even an array in place of Class.

These are added to the array list using

    myArray.add();

And the values are retrieved using

    myArray.get();