Question

Can someone explain what the following does?

private HashSet nodes[]; 
nodes = new HashSet[21];

I’m a little confused… in the difference between

private HashSet nodes = new HashSet;

and the above, particularly in terms of the square brackets syntax. Is this an array of HashSets? Because normally I’m used to seeing

int[] myarray = new int[21];

Or something like that.

Answer 1

Yes, it is an array of HashSets.

HashSet nodes[];

is the same as

HashSet[] nodes;

The difference in where you place the brackets only becomes important when you use commas to declare a bunch of variables at a time:

HashSet[] alpha, bravo, charlie; // Three arrays of hashsets
HashSet delta[], echo, foxtrot; // One array (delta) and two hashsets (echo and foxtrot)