hg: jdk8/tl/langtools: 7177701: error: Filling jar message during javax/imageio/metadata/IIOMetadataFormatImpl compilation

[Joe Darcy]

Hi David,

On 6/19/2012 6:14 PM, David Holmes wrote:
> Hi Maurizio,
>
> On 19/06/2012 10:27 PM, maurizio.cimadamore at oracle.com wrote:
>> Changeset: 34e254ffd0e7
>> Author:    mcimadamore
>> Date:      2012-06-19 13:25 +0100
>> URL:       http://hg.openjdk.java.net/jdk8/tl/langtools/rev/34e254ffd0e7
>>
>> 7177701: error: Filling jar message during 
>> javax/imageio/metadata/IIOMetadataFormatImpl compilation
>> Summary: Recent JDK hash changes affected order in which files are 
>> returned from JavacFileManager.list()
>> Reviewed-by: jjg
>>
>> ! src/share/classes/com/sun/tools/javac/file/ZipFileIndex.java
>
> That change seems fragile to say the least. Somewhere some piece of 
> code depends on the iteration order of the collection. The recent 
> changes meant that HashSet's returned order changed and broke things. 
> So you change to a LinkedHashSet which somehow restores the old order 
> (or at least reorders it yet again but in a way that doesn't cause a 
> problem).
>
> David

LinkedHashSet is specified to preserve insertion order in iteration: 
"This implementation [of LinkedHashSet] differs from HashSet in that it 
maintains a doubly-linked list running through all of its entries. This 
linked list defines the iteration ordering, which is the order in which 
elements were inserted into the set (insertion-order)."

Therefore, LinkedHashSet is just the right class to use when predictable 
iteration order matters :-)

-Joe