Java lambda expressions not supported at this language level

Question

I was testing out some new features of Java 8 and copied the example into my IDE  Eclipse originally  then IntelliJ  as shown here  Eclipse offered no support whatsoever for lambda expressions  and IntelliJ kept reporting an error      Lambda expressions not supported at this language level   I would like to know if this is a problem with my install  the code  or support

User · Answer

You should change source code Language Level also on the Source tab  Modules part

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This solution works in Android Studio 3 0 or later    File   Project Structure   Modules   app   Properties tab     Change both of Source Compatibility and Target Compatibility to 1 8   Edit config file   You can also configure it directly in the corresponding build gradle file  android              Configure only for each module that uses Java 8      language features  either in its source code or      through dependencies     compileOptions       sourceCompatibility JavaVersion VERSION 1 8     targetCompatibility JavaVersion VERSION 1 8

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For intellij 13   Simply change the Project language level itself to 8 0 with following navigation    File      ---------Project Structure - gt  Project tab                                Project language level     Module lang level  I also had to update Modules lang level when there was no maven plugin for java compiler   File      ---------Project Structure - gt  Modules tab                                 language level     But this Module lang level would automatically be fixed if there s already a maven plugin for it         lt plugin gt           lt groupId gt org apache maven plugins lt  groupId gt           lt artifactId gt maven-compiler-plugin lt  artifactId gt           lt version gt 3 6 0 lt  version gt           lt configuration gt               lt source gt 1 8 lt  source gt               lt target gt 1 8 lt  target gt           lt  configuration gt       lt  plugin gt    After changes everything looks good

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Adding below lines in app level build gradle in Android project solved issue   compileOptions           sourceCompatibility   JavaVersion VERSION 1 8         targetCompatibility   JavaVersion VERSION 1 8

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In intellij 14  following settings worked for me  Intellij14 Settings

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In IntelliJ IDEA   In File Menu   Project Structure   Project  change Project Language Level to 8 0 - Lambdas  type annotations etc   For Android 3 0  Go File   Project Structure   Module   app and In Properties Tab set Source Compatibility and Target Compatibility to 1 8  Java 8   Screenshot

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For latest users using Android studio 3 0 1 or above  Simply click Alt   Enter and upgrade your language level to 8 0 - Lambdas  type annotations etc

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If you are getting Not supported at Language 5  check this    For me it was in the Modules section

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7 0 does not support lambda expressions  Just add this to your app gradle to change your language level to 8 0   compileOptions       targetCompatibility 1 8     sourceCompatibility 1 8

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As Stephen C pointed out  Eclipse Kepler  4 3  has Java 8 support when the patch is installed  installation instructions here   Once installed  you   ll need to tell your projects to use java 8  First add the JDK to eclipse    Go to Window -  Preferences Go to Java -  Installed JREs Add Standard VM  and point to the location of the JRE Then go to Compiler Set Compiler compliance level to 1 8   Then tell the project to use JDK 1 8    Go to Project -  preferences Go to Java Compiler Enable project specific settings Set Compiler compliance level to 1 8

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To have support of Ecplise for lambda expressions     Make sure you are using JDK 1 8  Window   Preferences   Installed JREs  and Compiler    Use the annotation  FunctionalInterface if you define any new functional interfaces so that eclipse will suggest you refactorings related to Lambdas   Functional Interfaces

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First check the version of JDK you are using  it should higher than 1 8   If it is then proceed to do below steps   Change Language level of Project and modules in Intellij   Project     1 File- Project Structure- Project- Project language level      Change it to 8 for lamba expressions to work      2 File- Project Structure- Module- Project language level      Change it to 8 for lamba expressions to work

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In Android studio canary build 3     you can do the following   File -  Project Structure -  Look in Modules Section  there are names of modules of your class  Click on the module in which you want to upgrade java to 1 8 version  -  Change  Source Compatibility  and  Target Compatibility  to 1 8 from 1 7 or lower  Do not change anything else  -  Click Apply  now gradle will re-sync and your error will be removed

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Ctrl   Alt   Shift   S and then from project select the language level 1 8  read more about Lambda Expressions here

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this answers not working for new updated intelliJ    for new intelliJ    Go to --  file --  Project Structure --  Global Libraries     set to JDK 1 8 or higher version    also File --   project Structure ---  projects      set  project language manual  to 8   also File --   project Structure ---  project sdk     1 8  This should enable lambda expression for your project

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Just add compileOptions in build gradle yours app   android            defaultConfig               jackOptions         enabled true             compileOptions       sourceCompatibility JavaVersion VERSION 1 8     targetCompatibility JavaVersion VERSION 1 8

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To compile with Java 8  lambdas etc  in IntelliJ IDEA 15    CTRL   ALT   SHIFT   S or File   Project Structure Open Project tab Set Project SDK to compatible java version  1 8  Set Project language level to 8  Open Modules tab Set Language level to 8  click OK  CTRL   ALT   S or File   Settings Build  Execution  Deployment   Compiler   Java Compiler Change Target bytecode version to 1 8  click OK

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Check below settings    File- Project Structure- Project Tab     Project SDK should be set to 8 or above    File- Project Structure- Modules    Check that your or all modules has Language level set to 8 or above    File- Settings or Other Settings- Preference for new projects in newer Idea version    Search for Java compiler and check if Project byte code version  and per module byte code version is set 8 or above      You problem may fall into any one of the category defined above

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Even after applying above defined project specific settings on IntelliJ as well as Eclipse  it was still failing for me    what worked for me was addition of maven plugin with source and target with 1 8 setting in POM XML    lt build gt       lt plugins gt           lt plugin gt               lt groupId gt org apache maven plugins lt  groupId gt               lt artifactId gt maven-compiler-plugin lt  artifactId gt               lt version gt 2 0 2 lt  version gt               lt configuration gt                   lt source gt 1 8 lt  source gt                   lt target gt 1 8 lt  target gt               lt  configuration gt           lt  plugin gt            lt plugin gt               lt groupId gt org apache maven plugins lt  groupId gt               lt artifactId gt maven-jar-plugin lt  artifactId gt               lt configuration gt                   lt archive gt                       lt manifest gt                           lt addClasspath gt true lt  addClasspath gt                           lt classpathPrefix gt lib  lt  classpathPrefix gt                           lt mainClass gt com abc sparkcore JavaWordCount lt  mainClass gt                       lt  manifest gt                   lt  archive gt               lt  configuration gt           lt  plugin gt           lt plugin gt               lt groupId gt org apache maven plugins lt  groupId gt               lt artifactId gt maven-dependency-plugin lt  artifactId gt               lt executions gt                   lt execution gt                       lt id gt copy lt  id gt                       lt phase gt install lt  phase gt                       lt goals gt                           lt goal gt copy-dependencies lt  goal gt                       lt  goals gt                       lt configuration gt   lt outputDirectory gt   project build directory  lib lt  outputDirectory gt                       lt  configuration gt           lt  execution gt               lt  executions gt           lt  plugin gt       lt  plugins gt   lt  build gt

User · Answer

Possible Cause  1  same as the first 3 answers for this question   Project Structure Settings   File   Project Structure   Under Project Settings  go to Project   set Project SDK to 1 8  with version 65 or above  latest is 112  and set Project Language Level to 8  File   Project Structure   Under Platform Settings  go to Project   ensure that your JDK home path is set to 1 8  with version 65 or above  latest is 112     If the above does not work  check the target bytecode version of your compiler and move on to Possible Cause  2   Possible Cause  2  Compiler   File   Settings   Build  Execution  Deployment   Under Compiler  go to Java Compiler   set your Project Bytecode Version to 1 8  as well as all the Target Bytecode Version for your modules  Click Apply and hit OK  Restart your IntelliJ IDE  Lambda expression was accepted in my IDE at this point    Best wishes

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The same project  Android Studio 3 3 2  gradle-4 10 1-all zip  compileSdkVersion 28  buildToolsVersion  28 0 3   works fine on the new fast Windows machine and underline Java 8 stuff by red color on the old Ubuntu 18 04 laptop  however project is compiling without errors on Ubuntu    The only two things I have changed to force it to stop underlining by red were excluding of incremental true and dexOptions  compileOptions         incremental true     sourceCompatibility JavaVersion VERSION 1 8     targetCompatibility JavaVersion VERSION 1 8      dexOptions         javaMaxHeapSize  4g        in the app- level build gradle

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For me none of the solutions provided worked   This should be your last resort  -  Open  iml file of your project change the LANGUAGE LEVEL to JDK 1 8 or whatever version you wish  -  If this didn t help  you should grep  JDK  in your project root directory and find the file which contains version setting and set it to your preferred version

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Using  IntelliJ IDEA 2017 1 4 Build  IU-171 4694 23  Changing the language level via the Project Settings   Project tab didn t do anything   Instead hitting Alt   Enter and selecting  Set language level to 8 - Lambdas  type annotations etc   and it resolved automatically

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Actually  Eclipse support for Java 8 is available  see here and here    For Kepler  it is available as a  feature patch  against SR2  i e  Eclipse 4 3 2  For Luna  Eclipse 4 4  it will be in the standard release    release schedule

[java] Java "lambda expressions not supported at this language level"

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