Enumeration example from book by Bloch

Question

Hiya,
I would like to know how to do this stuff below AND if it has any sense with this construction of enumeration:
public enum Phase {
     SOLID, LIQUID, GAS;
     public enum Transition {
                //freeze2 it's made no sense but maybe does if I had another "kind" of object
          MELT(SOLID, LIQUID), FREEZE(LIQUID,SOLID), BOIL(LIQUID,GAS),  FREEZE2(LIQUID,SOLID), 
          CONDENSE(GAS,LIQUID), SUBLIME(SOLID,GAS), DEPOSIT(GAS,SOLID);
          final Phase src;
          final Phase dst;
          Transition(Phase src, Phase dst) {
               this.src = src;
               this.dst = dst;
          private static final Map<Phase, Map<Phase,Transition>> m =
               new EnumMap<Phase, Map<Phase, Transition>>(Phase.class);
          static {
               for (Phase p : Phase.values()) {
                    m.put(p, new EnumMap<Phase, Transition>(Phase.class ));
               for (Transition trans : Transition.values()) {
                    m.get( trans.src).put(trans.dst, trans);
          public static Transition from(Phase src, Phase dst) {
               return m.get(src).get(dst);
//main
//this below print out just Freeze2; I don't even know why; btw I'd like to have all transition LIQUID to SOLID, i.e freeze and freeze2
System.out.println( Phase.Transition.from(Phase.LIQUID, Phase.SOLID) );

Answer 1

mickey0 wrote:
Ok, I knew it was without sense. I even knew my problem was on Map. I just write "enumeration" because it's an enum exmaple in the book.
So: "pretending that FREEZE2 has sense": is there a way to rertrieve the two different Phase.??In the future, you'll get better answers if you use a meaningful subject, ask a question about the problem you're actually having, and use code that focuses on that problem, rather focusing on something else and having the problem as a minor bit on the side.
I can't really answer a nonsensical question by pretending it makes sense. I don't even know what you're asking. That is, if you were to have asked a question that makes sense, what problem would you really be trying to solve?
Your question is NOT simply "How do I get it to print both FREEZE and FREEZE2?" That doesn't even fit in with the example.
It looks like your question might be, "How do I associated multiple values with a single key in a Map?" If so, then the answer is, you don't, because java.util.Map is for mapping a key to a single value. Depending on your actual requirements and desired functionality, you might be able to do what you want by simply storing Lists or other Collections as the values, or you might have to download a third party collection that has a MultiMap or similar class (I think apache commons might), or write your own.
If that's not your question, then what is?