Forest f = new Forest(new Tree[]{m,p});?

Question

Im a Java beginner and I don't understand the following statement

Forest f = new Forest(new Tree[]{m,p}).

What I understand is that we construct a new Tree inside of a forest but the following expression {m,p} I dont understand. What baffles me are these type of brackets {. I thought that you always used () for a constructor. An explanation would be great.

PS.

Mango Tree m= new Mango Tree;
Pear Tree p = new PearTree();

Here you are constructing an array of type `Tree`in which you initially put `m`and `p` — Mustapha Belmokhtar, Oct 02 '17 at 08:27
What's the "PS" part about? It wouldn't compile for multiple reasons. — QBrute, Oct 02 '17 at 08:36

Eran · Answer 1 · 2017-10-02T08:30:25.547

3

new Tree[]{m,p} creates an array of Trees containing two Trees - referenced by m and p.

It is equivalent to:

Tree[] trees = new Tree[2];
trees[0] = m;
trees[1] = p;
Forest f = new Forest(trees);

or to:

Tree[] trees = {m,p};
Forest f = new Forest(trees);

edited Oct 02 '17 at 08:30

answered Oct 02 '17 at 08:26

Eran

387,369
54
702
768

score 1 · Answer 2 · answered Oct 02 '17 at 08:27

1

Curly braces are used to inizialize arrays.

int[] anArray = {0, 1}

is equivalent to

int[] anotherArray = new int[2];
anotherArray[0] = 0;
anotherArray[1] = 1;

Of course is the same for the Tree data type

answered Oct 02 '17 at 08:27

zuno

563
4
19

Forest f = new Forest(new Tree[]{m,p});?

2 Answers2