Define a concurrent hash set spring bean?

Question

In Spring I can define a HashSet like so in XML:

<bean id="subscriberStore" class="java.util.HashSet"/>

And, I can do the following in the code to create a concurrent hash set:

subscriberStore = Collections.newSetFromMap(
                     new ConcurrentHashMap<Subscriber, Boolean>());

But is there any way I can do this in one step in the XML? E.g. something like:

 <bean id="subscriberStore" class="java.util.HashSet"/>
         <  Some code here to set subscriberStore to the result 
    of Collections.newSetFromMap(new ConcurrentHashMap<Subscriber, Boolean>?   >

Many Thanks!

Boris Pavlović · Answer 1 · 2012-04-02T14:35:17.720

4

Bean configuration:

<!-- The bean to be created via the factory bean -->
<bean id="exampleBean"
      factory-bean="myFactoryBean"
      factory-method="createInstance"/>

<bean id="myFactoryBean" class="com.rory.ConcurrentHashMapFactory"/>

And the factory class:

public class ConcurrentHashMapFactory {
  public Set<Subscriber> createInstance() {
    Collections.newSetFromMap(new ConcurrentHashMap<Subscriber, Boolean>());
  }
}

edited Apr 02 '12 at 14:35

answered Apr 02 '12 at 12:51

Boris Pavlović

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1

Thanks, though shouldn't the createInstance return a Set rather than a Map? – Rory Apr 02 '12 at 13:09

score 0 · Answer 2 · edited May 23 '17 at 12:24

You could use something like the following:

<bean
    id="subscriberStore"
    class="java.util.Collections"
    factory-method="newSetFromMap"
>
    <constructor-arg>
        <bean class="java.util.concurrent.ConcurrentHashMap" />
    </constructor-arg>
</bean>

However, if generic types are important to you, create a custom, static factory method (as Boris Pavlović kind of suggests in his answer). You might want to take a look at this SO entry for some information regarding generics and Spring XML bean definitions.

Define a concurrent hash set spring bean?

2 Answers2