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From Lin Ma <lin...@gmail.com>
Subject Re: about source and target in maven-compiler-plugin
Date Mon, 30 Mar 2015 21:39:46 GMT
Thanks Sebastian,

Where to find the super pom.xml?

regards,
Lin

On Mon, Mar 30, 2015 at 1:18 AM, Sebastian Oerding <
sebastian.oerding@robotron.de> wrote:

> pom.xml uses inheritance. There is a so called 'super POM' provided with
> the maven installation from which all entries are inherited if not added /
> overwritten by you.
>
> Newer versions of Maven have Java 1.6 as default.
>
> With regards
> Sebastian
>
> -----Ursprüngliche Nachricht-----
> Von: Lin Ma [mailto:linlma@gmail.com]
> Gesendet: Montag, 30. März 2015 09:56
> An: Maven Users List
> Betreff: Re: about source and target in maven-compiler-plugin
>
> Thanks all the same Sebastian. Your reply is very helpful and bring us
> further thoughts.
>
> regards,
> Lin
>
> On Mon, Mar 30, 2015 at 12:47 AM, Sebastian Oerding <
> sebastian.oerding@robotron.de> wrote:
>
> > Hi Lin,
> >
> > I just tried my example and Maxim is right. I thought that the source
> > should take the API compatibility into account it seems that it is not
> > this way. Hence if the classes are successfully compiled (which
> > requires a JDK >
> > 1.5) and you are executing them with Java 1.5 the StringBuilder class
> > will not be in place -> ClassNotFoundException (the class format
> > should be as needed for Java 1.5 due to the target).
> >
> > However I will not tell anymore about it as I'm not completely sure
> > about the moment and I do not have the time to really dig into this.
> Sorry.
> > Detailed information about this is available in the net. In an earlier
> > email someone already provided links for the Maven documentation.
> >
> > Furthermore details about setting the compiler level can be found for
> > example in the Sun Certified Java Programmer Study Guide.
> >
> > With regards
> > Sebastian
> >
> > -----Ursprüngliche Nachricht-----
> > Von: Lin Ma [mailto:linlma@gmail.com]
> > Gesendet: Montag, 30. März 2015 09:38
> > An: Maven Users List
> > Betreff: Re: about source and target in maven-compiler-plugin
> >
> > Hi Maxim,
> >
> > Why compiler will not fail? Supposing StringBuilder is a class in JDK
> > 1.6, but we force compiler to use 1.5 which has no such class? Please
> > feel free to correct me if I am wrong.
> >
> > regards,
> > Lin
> >
> > On Mon, Mar 30, 2015 at 12:33 AM, Maxim Solodovnik
> > <solomax666@gmail.com>
> > wrote:
> >
> > > If I'm not mistaken compiler will not fail in this case BUT the
> > > application will fail in runtime (in case Java 1.5 is used) due to
> > > StringBuilder class is missing in JDK
> > >
> > > On Mon, Mar 30, 2015 at 1:20 PM, Lin Ma <linlma@gmail.com> wrote:
> > >
> > > > Thanks Sebastian,
> > > >
> > > > 1. I am using JDK 1.7/1.8 for both development and deployment in
> > > > runtime, shall I change 1.5 of source and target to 1.7/1.8?
> > > >
> > > > 2. In your example, "for example you can write source code using a
> > > > JDK
> > > 1.6
> > > > which is compliant to Java 1.5. However you can also use the
> > > StringBuilder
> > > > class which does not exist in Java 1.5", I think using JDK 1.6
> > > > specific feature but using 1.5 complier will fail? No? Please feel
> > > > free to correct me.
> > > >
> > > > regards,
> > > > Lin
> > > >
> > > > On Mon, Mar 30, 2015 at 12:14 AM, Sebastian Oerding <
> > > > sebastian.oerding@robotron.de> wrote:
> > > >
> > > > > source -> The level (JDK version) to which the source code must
> > > > > be compliant to, for example you can write source code using a
> > > > > JDK
> > > > > 1.6
> > > which
> > > > > is compliant to Java 1.5. However you can also use the
> > > > > StringBuilder
> > > > class
> > > > > which does not exist in Java 1.5 target -> The class version of
> > > > > the generated class files. The class
> > > > format
> > > > > changes with some Java version, for example as some stuff may be
> > > > > added
> > > > for
> > > > > performance reason. For example if a new byte code instruction
> > > > > comes up (like 'invokedynamic') this really makes a change. Or
> > > > > another example
> > > > (I'm
> > > > > not really sure about it): As far as I think a stack map has
> > > > > been added from Java 5 to Java 1.6. This should improve
> > > > > performance and makes
> > > subtle
> > > > > differences when ClassNotFoundException are thrown. You can use
> > > > > a JDK
> > > to
> > > > > compile code for different but lower versions. This way can
> > > > > benefit
> > > from
> > > > > some optimizations which weren't available with the old JDK and
> > > > > are compatible.
> > > > >
> > > > > With regards
> > > > > Sebastian
> > > > >
> > > > > -----Ursprüngliche Nachricht-----
> > > > > Von: Lin Ma [mailto:linlma@gmail.com]
> > > > > Gesendet: Montag, 30. März 2015 07:46
> > > > > An: Maven Users List
> > > > > Betreff: about source and target in maven-compiler-plugin
> > > > >
> > > > > Hello Maven masters,
> > > > >
> > > > > For maven-compiler-plugin(a sample below), have a quick question.
> > > > > I
> > > read
> > > > > this document
> > > > > (http://maven.apache.org/plugins/maven-compiler-plugin/
> > > ),
> > > > > and confused what means source and target 1.5 here, it seems it
> > > > > is an internal version number of Maven, independent of JDK?
> > > > >
> > > > > <plugin>
> > > > >     <artifactId>maven-compiler-plugin</artifactId>
> > > > >     <version>2.3.2</version>
> > > > >     <configuration>
> > > > >         <source>1.5</source>
> > > > >         <target>1.5</target>
> > > > >     </configuration>
> > > > > </plugin>
> > > > >
> > > > > thanks in advance,
> > > > > Lin
> > > > >
> > > > > ----------------------------------------------------------------
> > > > > --
> > > > > --- To unsubscribe, e-mail: users-unsubscribe@maven.apache.org
> > > > > For additional commands, e-mail: users-help@maven.apache.org
> > > > >
> > > >
> > >
> > >
> > >
> > > --
> > > WBR
> > > Maxim aka solomax
> > >
> >
>

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