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Eclipse Kepler is unable to set the Java jdk 1.8 when maven project is updated

Installed java version is 1.8, while selecting this version in pom.xml and updating the maven project,it automatically jumps from 1.8 to 1.4, due to which I am unable to have Lambda expression specific code.
I am using eclipse kepler.
Any idea what is happening here ?

Add something similar to this to your pom. You might have to tweak the plug in version.
<project>
[...]
<build>
[...]
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
[...]
</build>
[...]
</project>
Apologies I'm on mobile and the editor sucks for code formatting.
Edit: As noted in the accepted answer you also need to enable Java 8 support in Kepler.

With the help of Hogler's comment above I am able to reswolve this issue
Just did this :
https://wiki.eclipse.org/JDT/Eclipse_Java_8_Support_For_Kepler

Incremental java compile with maven (like Eclipse does)

I want to use maven to build projects in which there are unresolved compilation problems.
The main purpose is package and deploy or run aplications using some kind of stubs for classes that contains compilation errors, like I understand that Eclipse does (thanks to JDT Core).
I configurate maven java compiler plugin following Apache Maven documentation at Using Non-Javac compiler to use Eclipse compiler. Thinking that maybe should set some arguments to modify the compiler/builder behaivor I was reading Help Eclipse - Compiling Java code but I don't realize which compiler/builder option or combination of these does the trick.
So far, the next configuration of the maven java compiler plugins compile using the eclipse compiler and package the application including generated .class (jvm bytecode) only for java classes without compilation errors. To get this behaivor it just require use the eclipse compiler (see compilerId and the dependency) and set failOnError=false.
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<compilerId>eclipse</compilerId>
<source>1.7</source>
<target>1.7</target>
<optimize>true</optimize>
<showWarnings>true</showWarnings>
<showDeprecation>true</showDeprecation>
<failOnError>false</failOnError>
<compilerArguments>
<org.eclipse.jdt.core.compiler.problem.fatalOptionalError>disabled</org.eclipse.jdt.core.compiler.problem.fatalOptionalError>
<org.eclipse.jdt.core.compiler.problem.forbiddenReference>ignore</org.eclipse.jdt.core.compiler.problem.forbiddenReference>
</compilerArguments>
</configuration>
<dependencies>
<dependency>
<groupId>org.codehaus.plexus</groupId>
<artifactId>plexus-compiler-eclipse</artifactId>
<version>2.3</version>
</dependency>
</dependencies>
</plugin>
With this configuration I could run java application as long as the execution doesn't use classes not included for compilation errors (because the stubs aren't generated) but on a Java EE container, the classloading will faild so the application can never be deployed.
I appreciate any help on this.

Just for share the solution, at that moment I just replace the plexus-compiler-eclipse with tycho-compiler-jdt to get the desire behaivor.
The proceedOnError parameter indicates that it must keep compiling in spite of errors, dumping class files with problem methods or problem types how to deal with the compilation errors.
Next is the final configuration sample.
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<compilerId>jdt</compilerId>
<source>1.7</source>
<target>1.7</target>
<optimize>true</optimize>
<failOnError>false</failOnError>
<compilerArguments>
<proceedOnError/>
</compilerArguments>
</configuration>
<dependencies>
<dependency>
<groupId>org.eclipse.tycho</groupId>
<artifactId>tycho-compiler-jdt</artifactId>
<version>0.22.0</version>
</dependency>
</dependencies>
</plugin>
There is more plugin configuration examples in the Tycho FAQ.
And the possible compiler arguments are described in section Using the batch compiler of the Java development user guide (Eclipse Help site).

How can I switch the bytecode target level in IntelliJ using Maven 3 profiles

I am using maven profiles to switch between two "setups" in Intelli J. How can I switch the bytecode target level? That is: I want to change the following setting in compiler.xml
<bytecodeTargetLevel>
<module name="finmath-lib" target="1.6" />
</bytecodeTargetLevel>
Note: I tried to perform this via the following part in the respective Maven 3 profile
<profile>
<id>java-8</id>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</profile>
but this does not work!
Note: The pom.xml etc. belongs to the finmath lib project, and if you are interested, it can be found at www.finmath.net

I am using IntelliJ IDEA 14.1.3 and it works with following config ...
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.3</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
Hope this is helpful. Thanks!

The problem is that you want to change it to 1.8.
I've tried to switch IntelliJ's compiler version between 1.7 and 1.6 or 1.5 using Maven profile successfully.
However when you want to change it to 1.8, the config will be ignored.
I don't know whether this is maven's problem or Intellj's.
It seems that the JDK 1.8 is not well supported now, which is understandable.

You can open the Maven Projects tool window in IntelliJ and select the profile you want to use from the list.

In IntelliJ 13, File > Project Structure, set the Project language level to 8.0.

Compiling selected file with maven from command line [duplicate]

I want to compile only selected files or directories (including subdirectories) within source directory. I was pretty sure I can do this using <includes> of maven-compiler-plugin's configuration, but it seems to not work as I expect since it still compiles all classes into target/classes. What is really strange, Maven output suggest that the setting actually does its work, because with:
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.5.1</version>
<configuration>
<includes>
<include>com/example/dao/bean/*.java</include>
</includes>
</configuration>
</plugin>
I have:
[INFO] Compiling 1 source file to c:\Projects\test\target\classes
but with no compiler's configuration I have:
[INFO] Compiling 14 source file to c:\Projects\test\target\classes
In both cases however, all 14 classes are compiled into target/classes as I mentioned. Can you explain that or suggest another solution to compile only selected files?

Simple app with 3 classes.
com/company/Obj1.java
com/company/Obj2.java
com/company/inner/Obj3.java
build in pom.xml
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>2.0.2</version>
<configuration>
<source>1.6</source>
<target>1.6</target>
<includes>
<include>com/company/inner/*.java</include>
</includes>
</configuration>
</plugin>
</plugins>
</build>
result: 1 class is compiled.
And any combination of includes is working well
or you mean something else?

I have faced a similar situation. We needed to hot swap only modified files to our remote docker container in order to improve changes-deploy time. This is how we solved it.
Add includes option in build plugin with command line argument.
Note since we wanted to add multiple files, so we have used includes and not include
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.7.0</version>
<configuration>
<compilerVersion>1.8</compilerVersion>
<source>1.8</source>
<target>1.8</target>
<includes>${changed.classes}</includes>
</configuration>
</plugin>
Now run compile phase with argument, example:
mvn compile -Dchanged.classes=com/demo/ClassA.java,com/demo/ClassB.java,com/demo2/*

maven-compiler-plugin using Ant-like inclusion/exclusion notation.
You can see examples in Ant documentation Ant FileSet Type
If you are want include only files from one directory, you need write it like you did:
<include>com/example/dao/bean/*.java</include>
To include also subdirectories from path, it will be:
<include>com/example/dao/bean/**/*.java</include>

I had no difficulty including or excluding files for compilation with maven compiler plugin 2.5.1. Here is the dummy project I used for the purpose. Perhaps the include pattern that you use is different.

Does Maven really honor the <source> tag in the compiler plugin?

I work on a Java program that should be compatibe with Java 5. I had #Override annotations on implemented interface methods which is allowed in Java 6, but not in 5. I use a Java 6 SDK. Eclipse correctly gives error messages on the #Override when I set it to 5.0 compliance. My Maven build, however, runs without even a warning, using the following settings in my POM:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.5</source>
<target>1.5</target>
</configuration>
</plugin>
Am I correct in expecting that this should actually make the build fail? Why doesn't it, and is there something I can do?

This is actually a JDK problem, not a Maven problem. The #Override annotation is not failing with a -source 1.5 flag to to a 1.6 javac. Go ahead and try it. The only way to make it fail, is, unfortunately, to use a 1.5 javac.
Sorry, HTH.
EDIT
I ran into this problem myself, and I also wondered if it's actually looking at the setting in the pom. Turning on debug output (-X I believe, was a while ago) will print the javac command line to the standard output, and you'll see that it is indeed using the -source 1.5 parameter.

As roe's answer says you need to use a 1.5 compiler because the JDK isn't doing its job quite right. It's worth pointing out that you can avoid messing about with paths etc. by tweaking the maven-compiler-plugin configuration to use a specific compiler:
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<verbose>true</verbose>
<fork>true</fork>
<executable>${JAVA_1_5_HOME}/bin/javac</executable>
<compilerVersion>1.5</compilerVersion>
</configuration>
</plugin>
...
</plugins>
You can then specify the path to the compiler in your project or settings.xml
<properties>
<JAVA_1_5_HOME>/path/to/1.5jdk</JAVA_1_5_HOME>
</properties>