HashMap "String, color"

Moxl

Hi All!

I get unexpected token: > at line 3. Why?

class Mix {

  private HashMap<String, color> hm = new HashMap<String, color>();

  hm.put("910", color(232, 200, 95));
  hm.put("930", color(227, 189, 96));
  hm.put("960", color(212, 131, 92));

}

PS: is there an escape character to use greater/less than symbols in the question title?

amnon

color is Processing specific and when converting to java code it is replaced in the preprocessor by int, which is a primitive dataype, not an Object. You need an Object type, so in this case that would be Integer. The corrected line is thus:

HashMap <String, Integer> hm = new HashMap <String, Integer> ();

Then to answer your next question: "but now I get unexpected token: ( at line 5. Why?". You can't call methods there. You should format your class properly, by using variables, a constructor and methods. The corrected class is:

class Mix {
  HashMap <String, Integer> hm;

  Mix() {
    hm = new HashMap <String, Integer> ();
    hm.put("910", color(232, 200, 95));
    hm.put("930", color(227, 189, 96));
    hm.put("960", color(212, 131, 92));
  }
}

GoToLoop

A Java's Collection, like Map for example, can't use primitive types!
In your case, color is a syntactic sugar for primitive int! And its corresponding wrap class is Integer:
http://docs.oracle.com/javase/8/docs/api/java/lang/Integer.html

final HashMap<String, Integer> hm = new HashMap();

There's another bug: in order to run statements outside methods, we gotta place them inside curly braces:

//forum.processing.org/two/discussion/6843/hashmap-string-color

import java.util.Map;

class Mix {
  final Map<String, Integer> hm = new HashMap();
  {
    hm.put("910", color(232, 200, 95));
    hm.put("930", color(227, 189, 96));
    hm.put("960", color(212, 131, 92));
  }
}

Careful that doing so fails in JS Mode, unless it's not a nested class! And Mix is a nested inner class btW! :-SS

Alternatively, you can use the Processing 2's new class: IntDict, which accepts primitive types as values:
http://processing.org/reference/IntDict.html

Although it still uses a HashMap<String, Integer> internally called indices: 8-X
https://github.com/processing/processing/blob/master/core/src/processing/data/IntDict.java#L26

//forum.processing.org/two/discussion/6843/hashmap-string-color

class Mix {
  final IntDict hm = new IntDict
    (new String[] {
    "910", "930", "960"
  }
  , new color[] {
    color(232, 200, 95), 
    color(227, 189, 96), 
    color(212, 131, 92)
  }
  );
}

Is there an escape character to use greater/less than symbols...

Well, I use < for "less-than" myself! ;;)

P.S.: An excellent explanation about data-types. Worth the reading: :D
docs.oracle.com/javase/tutorial/java/nutsandbolts/datatypes.html

GoToLoop

Those keys "910", "930", "960" can be represented as numbers perfectly.
So why do you wanna them to be String btW? /:) Isn't an Integer key enough?! L-)

//forum.processing.org/two/discussion/6843/hashmap-string-color

import java.util.Map;

class Mix {
  final Map<Integer, Integer> hm = new HashMap();
  {
    hm.put(910, color(232, 200, 95));
    hm.put(930, color(227, 189, 96));
    hm.put(960, color(212, 131, 92));
  }
}

GoToLoop

BtW, I've found this explanation of mine in some old thread of yours: ;;)
http://forum.processing.org/two/discussion/6717/passing-variable-name-to-method

• Java's Collection containers, for example an ArrayList, can only store object references.
• We can't store primitives like int or float in them.
• Unless we use their corresponding primitive wrapper: Integer or Float, etc.
• Unless it's an immutable class, there's no much logic filling up a Collection w/ the same reference.
• Before populating a Collection, we gotta add() objects to it. Since it starts off empty!

Moxl

All right! Thanks a lot, guys.

amnon:

You should format your class properly

Of course. I forgot you must initilize variables in the constructor.

GoToLoop:

Those keys "910", "930", "960" can be represented as numbers perfectly.

Yes, perfectly true, but these are names in a standard a color model, some of which contain letters. The fact that only names made of digits appear in my example is simple awkwardness on my part for the post.

GoToLoop:

I've found this explanation of mine in some old thread of yours

You bet. That's the thread that got the HashMap thing rolling! I didn't know what that type did before.

Wrap class... Is a wrap class the one another extends from?

EDIT: OK I read this and I've understood it. Is this what a wrapper class is also called?

GoToLoop

Of course. I forgot you must...

"Must" is too strong of a word which rarely happens to be true in programming and anything else btW! :>
Generally, fields are initialized either "in situ" or further ahead inside a constructor or a delegated method for it.

However, when a field happens to refer to a data container, it's not such a bad idea to have an initialization block right next to it. Keeping both declarations & initializations close together makes code easier to study too! O:-)

GoToLoop

Wrap class... Is a wrap class the one another extends from?

A wrapper class is 1 that encapsulates some data in order to be used in some place which otherwise would be incompatible if used "in natura"!

More specifically I've meant Java's 8 primitive wrapper classes:
https://en.wikipedia.org/wiki/Primitive_wrapper_class