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https://issues.apache.org/jira/browse/LANG-1144?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15598131#comment-15598131
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Gary Gregory commented on LANG-1144:
------------------------------------
This seems like a valid bug report to me.
I do not think it reasonable to ask user to create a "special" null value for a
JDBC Connection or Statement, for example:
{code:java}
LazyInitializer<java.sql.Connection>
LazyInitializer<java.sql.Statement>
{code}
Now, I have to go and implement a "null" implementation of all the interfaces I
want to use? That's not acceptable.
Furthermore, what if I have a {{ComplexSomething}} class with many private
final fields that get initialized on construction to create a valid object? I
now have to change the class to allow of all null values? Not acceptable either.
> Multiple calls of
> org.apache.commons.lang3.concurrent.LazyInitializer.initialize() are possible
> -----------------------------------------------------------------------------------------------
>
> Key: LANG-1144
> URL: https://issues.apache.org/jira/browse/LANG-1144
> Project: Commons Lang
> Issue Type: Bug
> Components: lang.concurrent.*
> Affects Versions: 3.4
> Environment: Java 1.8 on Windows 7 x64
> Reporter: Waldemar Maier
> Attachments: 0001-LANG-1144-allow-nulls-as-return-value.patch
>
>
> It is possible to create a construct, that allows multiple calls of
> LazyInitializer.initialize, when calculations (which can be very expensive)
> return null as result.
> In the Javadoc is described that the initialize method will be called only on
> the first access
> {code:java}
> /**
> * Creates and initializes the object managed by this {@code
> * LazyInitializer}. This method is called by {@link #get()} when the
> object
> * is accessed for the first time. An implementation can focus on the
> * creation of the object. No synchronization is needed, as this is
> already
> * handled by {@code get()}.
> *
> * @return the managed data object
> * @throws ConcurrentException if an error occurs during object creation
> */
> protected abstract T initialize() throws ConcurrentException;
> {code}
> The Junit Test can be something like this:
> *(fix can be appplied from attached patch-file)*
> {code:java}
> package edu.test;
> import static org.junit.Assert.assertEquals;
> import org.apache.commons.lang3.concurrent.ConcurrentException;
> import org.apache.commons.lang3.concurrent.LazyInitializer;
> import org.junit.Test;
> public class LazyInitializerTest {
> private int lazyinitCounter = 0;
> private LazyInitializer<Object> lazyIinit = new LazyInitializer<Object>() {
> @Override
> protected Object initialize() throws ConcurrentException {
> lazyinitCounter++;
> return doSomeVeryExpensiveOperations();
> }
> };
>
>
> private Object doSomeVeryExpensiveOperations() {
> // do db calls
> // do some complex math calculations
> // the result of them all is null
> return null;
> }
>
>
> @Test
> public void testInitialization() throws Exception {
> lazyIinit.get();
> lazyIinit.get();
> assertEquals("Multiple call of LazyInitializer#initialize", 1,
> lazyinitCounter);
> }
> }
> {code}
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