How to create vector list or array of list in Java

Question

I want to create vector array like this in c++ in Java

vector<int> tab_u[255]

I don't have idea how to fast create. I try this:

List<Integer> tab[] = new List[255];

but i cant add something

i want something like this

[0] = {1,2,2,3}
[1] = {2,3}
[2] = {1}

A quick look at [oracle guide](https://docs.oracle.com/javase/tutorial/collections/interfaces/list.html) could save you from embarrassing situations like this one. — Ashvin Sharma, Sep 11 '19 at 08:46

score 2 · Answer 1 · answered Sep 11 '19 at 07:23

2

you can defined as;

Vector<Integer> vector = new Vector();

but as you may read here: vectors are kind of old...

Vector is an obsolete Collection

and maybe you should consider using another collection like an ArrayList

answered Sep 11 '19 at 07:23

ΦXocę 웃 Пepeúpa ツ

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score 2 · Answer 2 · answered Sep 11 '19 at 07:25

2

Try this:

ArrayList<String> cars = new ArrayList<String>();

cars.add("Volvo");
cars.add("BMW");
cars.add("Ford");
cars.add("Mazda");
System.out.println(cars);

I dont remember vectors in java but this is very similar. Hope it helps.

answered Sep 11 '19 at 07:25

Tomaz Mazej

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To make clear you are using an `interface` and a special implementation of it, you could have written `List cars = new ArrayList<>();` – deHaar Sep 11 '19 at 07:32
Yes, thats true! – Tomaz Mazej Sep 11 '19 at 07:39

score 0 · Answer 3 · answered Sep 11 '19 at 07:52

You need to do some additional work, because array initialization and array element initialization are separated.

List<Integer> myIntegerVectors = new List[255];  // Array initialized
for(int i = 0;i < myIntegerVectors.length; i++)  // Elements initialized in loop
    myIntegerVectors[i] = new ArrayList<>();

myIntegerVectors[7].add(1337);

How to create vector list or array of list in Java

3 Answers3