CODEWITHSUNDEEP
javaarrayssyntax
s0b0lev
s0b0lev

Reputation: 87

How do I initialize array when I do not know how much items will be there

I have a task, where I need to store data into arrays. But the problem which I met, that for using array I should initialize it. But I do not know how much items will be stored there. For example:

int[] array_name;
array_name = {1,2,3};

But my task is find numbers from string, and stored them into array, how much numbers will be there I do not know. Is there any universal way to initialize array?

Upvotes: 1

Views: 78

Answers (4)

AlexWien
AlexWien

Reputation: 28747

In that case you use an ArrayList.

ArrayList uses internally an array which grows automatically. If you insist on using an array, you can create one, once you have read in all data into your ArrayList.

Example:

List<Integer> numbers= new ArrayList<Integer>();
numbers.add(1);
numbers.add(2);
...

Upvotes: 6

Stein Dekker
Stein Dekker

Reputation: 803

Arrays in Java are not dynamic. You can use list instead.

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

Due to autoboxing feature you can freely add either Integer objects or primitive ints to this list.

Upvotes: 1

dorphalsig
dorphalsig

Reputation: 711

Create a List...

List myList = new ArrayList();

or with generics

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

If you definetly need an array, then after adding everything to the list, make it an array. More info here

Upvotes: 1

nano_nano
nano_nano

Reputation: 12523

I suggest you to use a List for that:

List<Integer> lIntegerList = new ArrayList<Integer>();

For using that there is no need to know how much Integers you have.

Upvotes: 1

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