IntelliJ IDEA 13 uses Java 1.5 despite setting to 1.7

Question

Despite specifying JDK 1.7 in all project settings (including in File -> Project Structure -> Project :: Project SDK), the following error is produced by

Answer 1

I managed to fix this by changing settings for new projects:

1. File -> New Projects Settings -> Settings for New Projects -> Java Compiler -> Set the version

2. File -> New Projects Settings -> Structure for New Projects -> Project -> Set Project SDK + set language level

3. Remove the projects

4. Import the projects

Answer 2

In IntelliJ Community Edition 2019.02, Changing the following settings worked for me

1. Update File->Project structure->Project Settings->Project->Project Language level to Java 11 (update to the java version that you wish to use in your project) using drop down.

2. Update File->Project structure->Project Settings->Modules->Language level

3. Update File->Settings->Build,Execution,Deployment -> Compiler -> Java Compiler-> Project ByteCode Version to java 11.

4. Update Target version for all the entries under File->Settings->Build,Execution,Deployment -> Compiler -> Java Compiler-> Per module Byte Code Version.

Answer 3

In your command line(Unix terminal) Go to your project root folder, and do this

find . -type f -name '*.iml' -exec sed -i '' s/JDK_1_5/JDK_1_8/g {} +

This will change the language level property in all your project .iml files from java 1.5 to java 1.8.

Answer 4

I had the following property working for me in IntelliJ 2017

  <properties>
        <java.version>1.8</java.version>       
  </properties>

Answer 5

Please check your project/module language levels (Project Structure | Project; Project Structure | Modules | module-name | Sources). You might also want to take a look at Settings | Compiler | Java Compiler | Per-module bytecode version.

Set also this:

File -> Project Structure -> Modules :: Sources (next to Paths and Dependencies) and that has a "Language level" option which also needs to be set correctly.

Answer 6

[For IntelliJ IDEA 2016.2]

I would like to expand upon part of Peter Gromov's answer with an up-to-date screenshot. Specifically this particular part:

You might also want to take a look at Settings | Compiler | Java Compiler | Per-module bytecode version.

I believe that (at least in 2016.2): checking out different commits in git resets these to 1.5.