Groovy to Java Code

Question

I know that such "general" questions shouldn't be asked, but can someone help me translate the following code from Groovy to Java. My main problem is, that I really do not know which datatypes in Java are similar to the ones of Groovy. Any help is welcome!

Many thanks!

  def registrations = [:]

  public void register(Class clazz, MessageListener listener) {
      def listeners = registrations.get(clazz)
      if (!listeners) {
          listeners = [] as Set;
          registrations.put(clazz, listeners)
       }
       listeners << listener
   }

Dónal · Accepted Answer · 2011-11-24 14:37:59Z

3

It would be something like this (untested):

Map<Class, Set<MessageListener>> registrations = new HashMap<Class, Set<MessageListener>>();

public void register(Class clazz, MessageListener listener) {
    Set<MessageListener> listeners = registrations.get(clazz);
    if (listeners == null) {
        listeners = new HashSet<MessageListener>();
        registrations.put(clazz, listeners);
     }
     listeners.add(listener);
 }

edited Nov 24, 2011 at 14:37

Dónal

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answered Nov 24, 2011 at 13:49

Stmated

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2 Comments

Stmated Over a year ago

Well, I posted mine 4 seconds before you, so I win! ;D Edit: Or maybe not, since mine does not compile because of lacking semi-colons. Edit2: But I fixed that, too.

bezmax Over a year ago

shamefully deletes his post

Community · Accepted Answer · 2017-05-23 10:08:12Z

2

Not an answer to the question (@Stmated has that covered), but if this is for a comparison to compare Groovy and Java, I believe your Groovy code could be better:

def registrations = [:].withDefault { [] as Set }

public void register(Class clazz, MessageListener listener) {
  registrations[ clazz ] << listener
}

edited May 23, 2017 at 10:08

CommunityBot

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answered Nov 24, 2011 at 14:14

tim_yates

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1 Comment

user801116 Over a year ago

Can you help me with my question

Michael Borgwardt · Accepted Answer · 2011-11-24 13:46:31Z

1

Simply use java.util.HashMap and java.util.HashSet for registrations and listeners respectively.

answered Nov 24, 2011 at 13:46

Michael Borgwardt

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