MESSAGE
| DATE | 2016-05-16 |
| FROM | ruben safir
|
| SUBJECT | Subject: [Hangout-NYLXS] Fwd: Re: hashtables syntax
|
-------- Forwarded Message --------
Subject: Re: hashtables syntax
Date: Sun, 15 May 2016 07:44:16 -0400
From: Eric Sosman
Organization: A noiseless patient Spider
Newsgroups: comp.lang.java.programmer
References:
On 5/15/2016 2:31 AM, Popping mad wrote:
>
> This whole syntax is new and strange to me, seemingly illogical
>
> private static HashMap functions; // built-in
> function types
>
> static { // initialize function types
> functions = new HashMap<>();
> functions.put("floor", new Type[]{Type.FLOAT, Type.INT});
> functions.put("sqrt", new Type[]{Type.FLOAT, Type.FLOAT});
> functions.put("log", new Type[]{Type.FLOAT, Type.FLOAT,
> Type.FLOAT});
> functions.put("random", new Type[]{Type.FLOAT});
> functions.put("parseInt", new Type[]{Type.STRING, Type.INT});
> functions.put("parseFloat", new Type[]{Type.STRING, Type.FLOAT});
> functions.put("readLine", new Type[]{Type.STRING});
> functions.put("showInt", new Type[]{Type.INT, Type.STRING});
> functions.put("showFloat", new Type[]{Type.FLOAT, Type.STRING});
> }
>
>
> If we are creating a private static Hashmap with template elements of a
> String and and array of Types, then why do I have to call
>
> functions = new HashMap<>();
You need to create the HashMap before you can start filling it.
You can't put the animals into the Ark before the Ark is built.
> and why nothing in the template. And what does static do in this case?
By "template" I guess you mean the <> angle braces? That's where
the type parameters would go, just as in the declaration. In fact, it
would be perfectly legal to repeat the parameters -- but since Java can
figure them out for itself ("Hmmm: They're probably the same types as
I already saw when `functions' was first declared!"), why bother?
As for `static', I'm not sure which of the two appearances confuses
you. The first `private static ... functions;' means that `functions'
belongs to the class as a whole, not to any instance of the class. If
`static' weren't there, each instance of the class would have its very
own `functions' map. The second appearance `static { // initialize ...'
means that this code belongs to the class as a whole and not to any
particular instance; it will execute when the class itself is being
set up -- and thus, will populate `functions' on behalf of the class.
--
esosman-at-comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM
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