HashMap<Point> ? Please explain

[RR_QQ]

Hello, so I've never seen this type of syntax. I need to create a Hashmap with each value having an (x,y) coordinate and I was told to do this:

HashMap<Point> h = new HashMap<Point>();

I know how to store items in a HashMap like this:

for (int i=0; i<strParts.length; i++) {
			
			// add all words except any remaining "-" (hyphens)
			if (!strParts[i].equals("-")) {
				mapStrParts.put(i, strParts[i]);
			}
		}

But how do I assign the Point x,y?

Any help is appreciated thank you!

[mrmatt1111]

I would suggest reading through the Generics Tutorial.

And you probably want this instead:

HashMap<Integer,Point> h = new HashMap<Integer,Point>();

Which would take in something like this:

h.put(0, new Point(0,0));
h.put(1, new Point(1,1));

System.out.println("Point 0 - " + h.get(0));

[RR_QQ]

Thanks a lot! just what I needed - what do you call the <> syntax????

[RR_QQ]

Oh I see this is "generic" thanks

[RR_QQ]

I have the following string input "a b c d" which I store in a hashmap with this code:

		HashMap<Point, String> mapStrParts = new HashMap<Point, String>();
		
		// loop through each of the string parts to save them in the HashMap
		for (int i=0; i<strParts.length; i++) {
			mapStrParts.put(new Point(0, i), strParts[i]);
		}

Later on I iterate through the HashMap to display the values/keys and this is what I get:

java.awt.Point[x=0,y=3]: d
java.awt.Point[x=0,y=0]: a
java.awt.Point[x=0,y=2]: c
java.awt.Point[x=0,y=1]: b

How exactly are teh values stored int he HashMap? The order I expected is:

java.awt.Point[x=0,y=0]: a
java.awt.Point[x=0,y=1]: b
java.awt.Point[x=0,y=2]: c
java.awt.Point[x=0,y=3]: d

any thoughts? Thank you

[mrmatt1111]

it is stored by the hash value of the key object, which would be in this case the points "hashCode()".

[Tolls]

There's no ordering with a HashMap either, so you really shouldn't expect any particular order back.

[RR_QQ]

Thanks for your input

[mtyoung]

if you wants to maintain order, use LinkedHashMap