Specification of Properties.load() does not define behaviour in case of duplicate keys

[Alan Bateman]

On 09/01/2020 09:35, Patrick Reinhart wrote:
> He everyone,
>
>
> When loading a properties file using java.util.Properties.load() the 
> behaviour for duplicate key values is not yet specified.
>
> The actual implementation overwrites existing key/value defined within 
> the current file by the further down without any warning or exception. 
> This has lead to various hard to detect errors as in big property 
> files, where multiple existences of the same property key.
>
> I would like to extend the existing specification in that regard that 
> only the first key/value pair will be taken into account and be added 
> to the properties.
>
> Alternatively new methods using this behaviour could also introduced...
Changing long standing behavior when properties files have duplicate 
keys could be problematic, esp. if there are properties files are 
bundled with a library that is deployed with different JDK releases. 
There was another discussion here recently about storing properties in 
canonical form, JDK-8231640 [1] was created to look into that. I only 
mention because there is other "projects" in this area if you want to 
look into that too.

-Alan

[1] https://bugs.openjdk.java.net/browse/JDK-8231640