Why do I get error "Lambda expressions are not supported in -source 1.6"?

Question

I'm using IntelliJ Idea and I get this error.

Lambda expressions are not supported in -source 1.6

Got this when I updated from 2016 to the 2017 version of the community edition after I did something with gradle.

Settings: Java compiler: Project bytecode version: 1.8 Modules bytecode version: 1.8 Project SDK: 1.8 Project language level: default(8) Modules 1.8 as well

You probably switched your java version to 1.6 by accident. Try updating java to 1.8 in order to have access to lambda function api's. — John Gallagher, Aug 13 '17 at 17:21
I only have java 8 installed, both SDK and JRE 8 version 144 — jordibenck, Aug 13 '17 at 17:22
Check your java version with `java -version` command. If by some reason you have 1.6 version then uninstall it or set `JAVA_HOME` environment variable to `jre_1.8.X/bin` directory. — Aleksei Budiak, Aug 13 '17 at 17:23
Check your IDE settings, you may have it (or gradle) to Java 1.6 — Elliott Frisch, Aug 13 '17 at 17:24
[This answer/suggestion](https://stackoverflow.com/a/45361596/7598776) might help — Robin Topper, Aug 13 '17 at 17:27
You can't expect to use Java 1.8 features with `-source 1.6`. — trashgod, Aug 13 '17 at 17:27

score 1 · Accepted Answer · answered Aug 13 '17 at 17:29

Check Settings -> Compiler - > Java Compiler. If that doesn't work, for MAVEN: you can set it in your pom.xml, like this:

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

for gradle :

sourceCompatibility = "1.8"; 
targetCompatibility = "1.8"; // defaults to sourceCompatibility

Ali Faris · Answer 2 · 2017-08-13T17:41:08.597

1

that because in you IDEA the Project language level set to "6 - @Override in interface"

to solve goto:

File -> Other Setting -> Default Project Structure

now change Project language level to Lambdas , type annotation etc. and then click OK

edited Aug 13 '17 at 17:41

answered Aug 13 '17 at 17:33

Ali Faris

17,754
10
45
70

Why do I get error "Lambda expressions are not supported in -source 1.6"?

2 Answers2