Why won't eclipse switch the compiler to Java 8?

Question

I checked out a Java project from SVN in eclipse and realized that it requires Java 8 because it uses lambdas etc. I installed the eclipse addon for Java 8 and restarted ecl

Answer 1

I had the similar problem with eclipse kepler.I have followed these steps to resolve it

• Go to Help in Eclipse and Oper Eclipse Market Place option.
• Search for jdk 1.8 for kepler
• Install the required plugin.
• Restart the eclipse.

for reference, refer this link http://techno-terminal.blogspot.in/2016/05/jdk-18-compiler-compliance-is-not.html

Answer 2

It cause eclipse kepler SR1 does not support new Java™ 8 language enhancements like lambda expression.

From information here: http://www.eclipse.org/downloads/java8/
I think you should use kepler SR2 with support plugin, or change to Eclipse Luna.

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Updated link 16/09/2016: https://wiki.eclipse.org/JDT/Eclipse_Java_8_Support_For_Kepler

Answer 3

I had the same problem even though I had:

• a freshly downloaded JDK 1.8.0

• JAVA_HOME is set

• java -version on command line reports 1.8

• Java in control panel is set to 1.8

• downloaded Eclipse Mars

Eclipse only let me choose a compiler compliance level op to 1.7 in the compiler preferences, even though my installed JRE is 1.8.0. I also couldn't see a 1.8 in the Execution Environments underneath Installed JREs, only a JavaSE-1.7 (which I haven't even got installed!). When I clicked on that, it shows "jdk1.8.0" as a compatible JRE, so I selected that, but still no change.

Then I unzipped Eclipse Mars into a brand new directory, created a new project, and now I can select 1.8, hurrah! That greatly reduced the "Duplicate methods named spliterator..." errors I was getting when compiling my code under Java 1.8, however, there is still one left:

Duplicate default methods named spliterator with the parameters () and () are inherited from the types List and Set.

However, that's likely because I'm extending AbstractList and implementing Set, so I've fixed that for now by removing the implements Set because it doesn't really add anything in my case (other than signifying that my collection has only unique elements)

Answer 4

First install the JDK1.8 set to Path Open Eclipse and Oper Eclipse Market Place option. Search for jdk 1.8 for kepler Install the required plugin. Restart the eclipse. Change compiler level to 1.8 from preferences. If still there is an error then click on the file and change the compiler setting explicitly to Jdk 1.8

Answer 5

<build>
        <plugins>
            <plugin>
                <groupId>org.apache.maven.plugins</groupId>
                <artifactId>maven-compiler-plugin</artifactId>
                <version>3.6.1</version>
                <configuration>
                    <source>1.8</source>
                    <target>1.8</target>
                </configuration>
            </plugin>
        </plugins>
    </build>

Answer 6

Old question, but posting the answer incase it helps someone. Already build path was configured to use JDK 1.2.81 However, build was failing with the error below:

 lambda expressions are not supported in -source 1.5
[ERROR]   (use -source 8 or higher to enable lambda expressions)

In the latest Eclipse (Photon), adding the below entry to pom.xml worked.

  <properties>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <maven.compiler.target>1.8</maven.compiler.target>
    <maven.compiler.source>1.8</maven.compiler.source>
  </properties>