How to define a public vector in Java?

Question

I am trying to pass a vector of vectors from one class to another one. For regular parameters and arrays I used something like this:

public static double[] x= new double[100];

However, this is not working for a vector or a vector of vectors:

public Vector<Vector<Integer>> vec2 = new Vector<Vector<Integer>>();
public Vector<Integer> vec = new Vector<Integer>();

How can we retrieve a vector of vectors in other classes?

You forgot to make the fields static? Also note: http://stackoverflow.com/questions/1386275 — Durandal, Feb 08 '16 at 20:59
this is how you define a vector of vectors. vec2 and vec are empty after the `new` calls — DBug, Feb 08 '16 at 20:59
Post an [MCVE](http://stackoverflow.com/help/mcve). Be sure to copy-paste your code to a *new project* and make sure it compiles and runs before posting it here. — user1803551, Feb 08 '16 at 21:03
@Nima "Not working" is not a sufficient problem description when you give zero context and no indication what you are trying to solve. Describe what problem you have exactly. — Durandal, Feb 08 '16 at 21:14

score 0 · Answer 1 · edited May 23 '17 at 12:23

Consider the following code for your actual problem, maybe it could help you understand better :

    //These are the Integers your vector will contain
    Integer i1 = new Integer(1);
    Integer i2 = new Integer(2);
    Integer i3 = new Integer(3);
    Integer i4 = new Integer(4);

    //This is the vector you're going to insert them into (You could create more than one)
    Vector <Integer> v1 = new Vector<>();

    v1.add(i1);
    v1.add(i2);
    v1.add(i3);
    v1.add(i4);

    //This is the vector of vectors you're going to use to contain your previous vector
    Vector <Vector<Integer>> vectorOfVectors= new Vector<>();

    vectorOfVectors.add(v1);

    //To test out your code
    System.out.println(v1.toString());
    System.out.println(vectorOfVectors.toString());

But consider not using the Vector class as suggested in the following post : Why is Java Vector class considered obsolete or deprecated? There are better options such as the Collection Interface's ArrayList.

The Java tutorial offers a complete guide as to how to use the Collections Interface. I suggest you study it closely as it is really useful for any type of collections you could need. Here's the link.

How to define a public vector in Java?

1 Answers1