Java Vector of Int Pair

Question

I want to have a vector of integer pairs in Java so I can store Cartesian coordinates in each cell. So it would look like :

|2,3|4,5|5,6|6,7|

Each cell of the vector has 2 ints. I tried doing this:

Vector<pair<Integer,Integer>> test = new Vector<pair<Integer,Integer>>();

But java could not resolve the word pair (even when I did ctrl+shift+O in eclipse to import all relevant libraries). Then I tried this:

Vector<pair<int,int>> test= new Vector<pair<int,int>>();

But it doesn't like the keyword int for some reason. Any ideas on how to make a vector of int pairs in Java?

Well where did you expect the `pair` type to come from? Also note that you can't use primitive types in Java generics, which is why `pair` won't work. — Jon Skeet, Apr 22 '14 at 14:56
That's impossible using just Generics! Congratulations, you hit the Erasure bound.7 — tilpner, Apr 22 '14 at 14:56
Please don't rely on Vector anymore. This class is from a long time past. Use an ArrayList or similar. — Ray, Apr 22 '14 at 14:57
It looks an awful lot like you're just translating C++ STL code directly into Java. Java collections are not the same as STL containers, and Java genetics don't work the same as C++ templates, despite the surface similarities. — Laurence Gonsalves, Apr 22 '14 at 15:03

score 2 · Accepted Answer · answered Apr 22 '14 at 14:56

2

I suggest you use e.g. java.awt.Point for this.

It has 2 int coordinates, just what you need.

new Vector<java.awt.Point>

Also, as others noted already, in fact you should use

new ArrayList<java.awt.Point>

and not use Vector.

answered Apr 22 '14 at 14:56

peter.petrov

score 2 · Answer 2 · edited May 23 '17 at 10:24

2

There is no "pair" in Java. But you can implement it yourself, like suggested here: Creating a list of pairs in java

edited May 23 '17 at 10:24

Community

answered Apr 22 '14 at 14:57

schof

score 2 · Answer 3 · answered Jun 04 '18 at 15:26

I had the same problem and since using $ Pair<Integer, Integer> was not a good option for me, I created a small class like

class TestPair{
    int i;
    int j;
}

And then I just normally used the ArrayList

ArrayList<TestPair> testArr = new ArrayList<>();

score 0 · Answer 4 · answered Jun 26 '18 at 15:58

Min requirement - Java 8 (As till Java 7 Pair class didn't exist).

JavaFX 2.2 has the javafx.util.Pair class which can be used to store a pair.

First import the JavaFX as import javafx.util.Pair;

For example:

Pair p1 = new Pair(1,7); Pair p2 = new Pair(2,6); Pair p3 = new Pair(1,7); System.out.println(p1.equals(p3) + “and” + p2.equals(p3));

OUTPUT : true and false

This way you can use similar methods like getKey() and getValue() etc. Check the doc for more methods and example code snippets.

4 Answers4