macports vs java

[Blair Zajac]

On 06/14/2013 12:40 PM, Leo Singer wrote:
> On Jun 14, 2013, at 10:00:42 AM PDT, blair at orcaware.com wrote:
>
>> On 06/14/2013 08:49 AM, Jack Howarth wrote:
>>>     Can someone clarify what the situation is with Java and MacPorts? On fink, we have a number
>>> of packages (like graphviz) which previously have been built against the JavaVM.framework
>>> in /System/Library/Frameworks. We had hoped to transition to the Oracle JDK for this but
>>> they both don't use a framwork build but also stupidly install the JDK in a versioned directory
>>> which will change with each Java 1.7 update. Unfortunately they don't install a generic symlink
>>> that would allow the path for linkages to survive these updates (eg /Library/Java/JavaVirtualMachines/jdk1.7.jdk
>>> to point at /Library/Java/JavaVirtualMachines/jdk1.7.0_21.jdk, etc). It is unclear where the JRE
>>> standalone package is installing as they use a sandbox during the installation. Any clarifications
>>> and advice on this transition is welcome.
>>
>> I've got two thoughts on Java packages in general:
>>
>> 1) I don't see the point of us doing builds, it's better just to unpack the upstream package which contains jars, wars, etc.  This of course doesn't work for development versions, but in practice, we don't have many -devel Java packages, especially when people get their jars from Maven or Ivy.
>>
>> 2) Unless there's code specifically in the package that needs new classes in JDK 7, it's better to compile against JDK 6 so that the class files are JDK 6 compatible.  One could pass to JDK 7's javac the target flags.
>
> Better still is to build with the latest JDK, but use javac's -source and -target options to specify the minimum compatible Java language version and minimum compatible JVM version.

I'm coming with my developer's hat on, because even with the the target 
flags, if you inadvertently use a new JDK 7 method and target JDK 6, 
it'll still compile but fail at runtime on the older JDK, e.g. 
String#isEmpty which was added in JDK 6.

But yes, this doesn't matter much for MacPorts.

Blair