Getting Started with Spring Boot

Duplicate entries put into HashSet Java issue

I have recently run into an issue using HashSet.addAll(Object) where duplicates are added to my Set.

I even made sure that the Object I was using Overrode hashCode().

Apparently the addAll() implementation for HashSet doesn't check for duplicates.  This is bad because a reason for using a Set over a List is to avoid duplicate values.

If you loop through all of the values in the collection you are adding to the Set it works as expected not adding the duplicates.  This is the approach I took to get around this issue.

for (item in myCollection){
    set.add(item)
}

vs what I was trying to do which didn't work:

set.addAll(myCollection)

Another approach could be extend the HashSet and override the addAll() with the logic I used.

Using Groovy Closures To Simplify Working With Alfresco Transactions

If you are familiar with Alfresco transactions than you will be familiar with the following:
  
Boolean result = transactionService.getRetryingTransactionHelper().doInTransaction(new RetryingTransactionHelper.RetryingTransactionCallback<Boolean>() {
            public Boolean execute() throws Throwable {
                //Your code
                return true;
            }
}, false, true);
This is quite a bit of code and gets ugly if you start embedding a bunch of code inside this block. It is also not very testable with out some crazy mocking.


Groovy Closures to the rescue. http://groovy.codehaus.org/Closures
I created a simple TransactionHelper Groovy class with a method that takes a closure and wraps the closure inside of the above code required for a transaction and wired it as a Spring Bean.

import org.alfresco.repo.transaction.RetryingTransactionHelper
import org.alfresco.service.transaction.TransactionService
class TransactionHelper {
    private TransactionService transactionService
    def executeInSperarateTransaction(closure) {
        Boolean result = transactionService.getRetryingTransactionHelper().doInTransaction(new RetryingTransactionHelper.RetryingTransactionCallback<Boolean>() {
            public Boolean execute() throws Throwable {
                closure()
                return true
            }
        }, false, true)
    }
    void setTransactionService(TransactionService transactionService) {
        this.transactionService = transactionService
    }
}

Now if I need to execute a transaction I can simply do the following.
transactionHelper.executeInSperarateTransaction({ nodeService.addAspect(nodeRef, MyModel.THUMBNAIL_ASPECT, new HashMap<QName, Serializable>())})

You can simply pass a closure statement like above or pass in a closure like the following.

def closure() {
  def localVariable = new java.util.Date()
  return { println localVariable }
}
transactionHelper.executeInSeperateTransaction(closure)
 

For more information on Groovy and Closures see http://groovy.codehaus.org/Closures