Compiling Xtend code to Java 8 with Maven

[Norbert Sándor]

Hello,

I have read some posts about this topic but I cannot get compilation to work with Java 8 source level...

I think I have everything in place:

• maven-compiler-plugin: source and target is set to 1.8
• maven-toolchains-plugin: jdk/version is set to 1.8

During compilation the toolchain is applied:

[INFO] --- xtend-maven-plugin:2.9.0:compile (default)
[INFO] Using toolchain JDK[...\jdk1.8.0]

But when I try to compile an interface with a default method, I get the following error:

ERROR:  IocApi.xtend - ...\IocApi.xtend
266: Abstract methods do not specify a body

In Eclipse, the same code compiles without problems.

Any ideas?

Thanks,
Norbi

[Norbert Sándor]

If you have some time to try it:

• clone https://github.com/NorbertSandor/xtend-ioc.git
• cd xtend-ioc-project
• mvn compile

Error message:

[INFO] --- xtend-maven-plugin:2.9.0:compile (default) @ xtend-ioc-core ---

[INFO] Using toolchain JDK[...\jdk1.8.0]

[ERROR]
ERROR:  IocApi.xtend - ...\xtend-ioc-project\xtend-ioc-core\src\main\java\com\erinors\ioc\shared\api\IocApi.xtend
268: Abstract methods do not specify a body

In Eclipse it compiles as expected.

Thanks for your help in advance.
Norbi

[Norbert Sándor]

Sorry, you should use

mvn compile -P!release

because some Maven components are configured only on my machine :)

[Norbert Sándor]

I see something related in the detailed Maven log:

[DEBUG] Configuring mojo 'org.eclipse.xtend:xtend-maven-plugin:2.9.0:compile' wi
th basic configurator -->
...
[DEBUG]   (f) javaSourceVersion = 1.6
...
[DEBUG] Set Java Compliance Level: 1.6
...

But where do these settings come from?

[Norbert Sándor]

I solved it by explicitly specifying

<javaSourceVersion>1.8</javaSourceVersion>

in the xtend-maven-plugin configuration.

[Stefan Oehme]

Hi Norbert,

Xtend cannot see the configuration of the java plugin. But maven has two useful properties you can set instead. These are understood by both java and xtend.

<properties><maven.compiler.source>1.7</maven.compiler.source>
<maven.compiler.target>1.7</maven.compiler.target>
</properties>

Cheers,
Stefan

[Norbert Sándor]

Thanks!

(I think it works only if all xtend projects are built with the same Java source level.)

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[Stefan Oehme]

You can set that property differently on different projects if you want.