Develop Reference

Eclipse Mars with m2e can not change java compile path

While trying to do a maven compile goal on a jar project in eclipse it failed stating that there was no java compiler found. It showed that it was using the path to jre1.8.0_45. My configured java build path in eclipse is using jdk1.7.0_80 and is configured for the correct corresponding environment.
I tried to rename the jre directory while eclipse was open but it showed that something had a lock on it, and sure enough it was eclipse that was launching with jre1.8. If I renamed the jre1.8 directory while eclipse was closed, then it would not launch again complaining that it cant find the java directory.
I guess what I'm getting at here is, is this a bug with Mars? Or am I missing something because everything in Eclipse is pointed to 1.7.
Thanks,
Nate

You should point Eclipse to JDK installation.
Window -> Preferences -> Java\Installed JREs
click Add -> Select Standard VM, Next ->
and then in text box "JRE home" you should put path to JDK home,
it's quite misleading..
BTW you should specify java version in maven-compiler-plugin. M2E plugin will then recognize this settings and configure compiler appropriatelly
http://www.gamefromscratch.com/post/2011/11/15/Telling-Eclipse-to-use-the-JDK-instead-of-JRE.aspx

It's the launch configuration of any m2e build that should point to a full JDK, cf. http://help.eclipse.org/mars/topic/org.eclipse.jdt.doc.user/tasks/task-choose_config_jre.htm?cp=1_3_5_2 (except you will be using a Maven Build configuration, rather than a Java Application).
For most other situations using a JRE should be perfectly fine.

Eclipse/Maven error: "No compiler is provided in this environment"

My environment is Windows 7 64bit with Eclipse [Kepler SR1] and Maven. I have to run a Maven install to deploy a code change, but this error is showing in the console:
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.1:compile (default-compile) on project mrpapp: Compilation failure
[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?
but I definitely am running a JDK and not a JRE. I double-checked my $JAVA_HOME (C:\Program Files (x86)\Java\jdk1.7.0_60) and it does have a javac.exe in its bin directory.

Go to Window → Preferences → Java → Installed JREs.
And see if there is an entry pointing to your JDK path, and if not, click on Edit button and put the path you configured your JAVA_HOME environment.

Screen_shot
Add 'tools.jar' to installed JRE.
Eclipse -> window -> preference.
Select installed JREs -> Edit
Add External Jars
select tools.jar from java/JDKx.x/lib folder.
Click Finish

Go into Window > Preferences > Java > Installed JREs > and check your installed JREs. You should have an entry with a JDK there.
https://cduu.wordpress.com/2013/03/08/maven-eclipse-compiler-error-no-compiler-is-provided-in-this-environment/

I tried all the things; the one that worked for me is:
Right click on Eclipse project and navigate to properties.
Click on Java Build Path and go to the Libraries tab.
Check which version of Java is added there; is it JRE or JDK?
If you are using Maven project and want to build a solution.
Select the JRE added their and click remove.
Click Add external class folder and add the JDK install by selecting
from the system.
Click Apply and OK.
Restart Eclipse.
Build succeeded.

Add this configurations in pom.xml
<project ...>
...
<build>
...
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>1.7</source>
<target>1.7</target>
<fork>true</fork>
<executable>C:\Program Files\Java\jdk1.7.0_79\bin\javac</executable>
</configuration>
</plugin>
</plugins>
</build>
...
</project>

When I was runing mvn compile, I was getting below error in console:
[INFO] Changes detected - recompiling the module!
[WARNING] File encoding has not been set, using platform encoding Cp1252, i.e. build is platform dependent!
[INFO] Compiling 1087 source files to C:\Code\DevVNextComplete\Development_vNext\Source\JARS\target\classes
[INFO] -------------------------------------------------------------
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?
[INFO] 1 error
[Resolution]
I had added, the JAVA_HOME variable in my environment variables and then it worked.

This worked for me.
1. Click on Window-> Preferences -> Installed JRE.
2. Check if you reference is for JDK as shown in the image below.
If not, Click on Add-> Standard VM -> Give the JDK path by selecting the directory and click on finish as shown in the image
Last step, click on Installed JREs -> Execution Environments -> select your JDE as shown in the image below
Maven -> Clean

I also faced similar error when I was working with Jdk1.8_92.
For me, I found tools.jar was missing in my jdk folder.
Since I was running in console, I couldn't try the options of eclipse suggested by others..
I installed jdk-8u92-windows-x64.
After I tried all options, I observed that tools.jar was missing in jdk1.8.0_92/lib folder.
I copied tools.jar from my older version of java.
Then It was able to compile.

I was getting the same error when trying to execute a maven build within Eclipse in a newly installed Eclipse Neon (for JEE devs) installation, on Windows 10 with JDK 8 and JRE 8 installed.
I had tried specifying tools.jar as an external lib, as well as setting the jdk as the -vm in eclipse. Neither of these things worked.
Selecting the JDK as the default execution env as mentioned above did the trick..
Eclipse->window->preference->java->Installed JREs->Execution Environments.
Select JavaSE-1.8
Check JDK1.8 in "Compatible JREs".
The text above the compatible JREs listbox in step 3 says "a default JRE can be specified by checking it"
Note: I also have the maven compiler plugin explicitly listing 1.8 in the pom
<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>

Follow :
Windows --> Preferences --> Java ---> Installed JREs
Click on "Search.."
Navigate to C drive ---> Program files
Eclipse will find all the jre's and jdk's --> select one of the jdk and select Apply

Please check if you have the following entries in the element of your pom.xml especially the jdk.version because switching to an installed jre did not fix me the similar error.
<properties>
<jdk.version>1.7</jdk.version>
<spring.version>4.1.1.RELEASE</spring.version>
<jstl.version>1.2</jstl.version>
<junit.version>4.11</junit.version>
</properties>

if someone is running Eclipse in Ubuntu and have this problem I have found the answer by following these steps:
Eclipse->window->preference.
Select installed JREs->Add
Select standardVM.
JRE home: press [Directory..] button.
Choose your java (my problem was my eclipse was running with java8 and my VM were with java7), in my case java8 was installed in usr/local/jvm/java-8-oracle.
Press finish.
Then press installed JRES arrow so you can see the other options.
Go to Execution Environment.
Select JavaSE-1.6 on left and in the right (the compatible JRE) you have to choose the Java you have just installed( in my case java-8-oracle). you have to do this steps with JavaSE1.8.
Click OK and restart Eclipse.

Installed JRE
In my case I solved the problem by removing duplicates of names, I kept only one with the name: jdk.1.8.0_101

In my case, I had created a run configuration and whenever I tried to run it, the error would be displayed. After searching on some websites, I edited the run configuration and under JRE tab, selected the runtime JRE as 'workspace default JRE' which I had already configured to point to my local Java JDK installation (ex. C:\Program Files (x86)\Java\jdk1.8.0_51). This solved my issue. Maybe it helps someone out there.

was getting the same problem, pointed java to bin folder in eclipse using:
windows > preferences > java > installed JREs > remove any existing JRE and point it to your java bin folder (mainly under C:\Program Files\Java\jdk1.8.x_xx).
then run maven install it should work.

To check what your Maven uses, open a command line and type:
mvn –version
Verify that JAVA_HOME refers to a JDK home and not a JRE
On Windows:
Go to System properties -> Advanced system settings -> Advanced -> environment variable and on the System variables section select the JAVA_HOME variable and click on Edit
Fill the form with the following
Variable name: JAVA_HOME
Variable value:
On Unix:
export JAVA_HOME=<ABSOLUTE_PATH_TO_JDK>
see this link

Uninstall older Java(JDK/JRE) from the system( Keep one (latest) java version), Also remove if any old java jre/jdk entries in environment variables PATH/CLASSPATH
Eclipse->Window->Preferences->Installed JREs->Add/Edit JDK from the latest installation
Eclipse->Window->Preferences->Installed JREs->Execution Environment->Select the desired java version on left and click the check box on right
If you are using maven include the following tag in pom.xml (update versions as needed) inside plugins tag.
<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>
Right click on eclipse project Maven - > Update Project

For me (on windows 10), I was getting the error "No compiler is provided in this environment" at the Windows command prompt when I ran mvn install. The fix was changing the JAVA_HOME environment variable to point to my jdk (C:\Program Files\Java\jdk1.8.0_101); previously it had pointed to the jre.
And to get Eclipse to use the new jdk, I edited eclipse.ini in my eclipse distribution and changed the line for -vm to C:\Program Files\Java\jdk1.8.0_101\bin.

check java version in pom.xml and jre version in Eclipse->Window->Preferences->Installed JREs. In my case pom.xml has different version(it had 1.8 while eclipse using 1.7). Fixing the version in pom.xml to 1.7 worked.

if you are working outside of eclipse in the command window
make sure you have the right JAVA_HOME and that that directory contains the compiler by entering the following command in the command window:
dir %JAVA_HOME%\bin\javac.*

1.Go to Windows-->Preferences-->Java-->Installed JREs-->Execution Environments
2.select the java version you are using currently in the "Execution Environments" box.
So that in the "Compatible JREs" box, you are able to see as "jre1.8.0_102[perfect match]"(if your java version is 1.8). Then try to build using maven.

Maven requires JDK to compile. In Eclipse you need to CHANGE/ REPLACE your JRE to the JDK path that your JAVA_HOME points to. Navigate to Window > Preferences > Java > Installed JREs.
Make sure that the maven-compiler-plugin in you pom.xml has the source and target of the java version in your JAVA_HOME
http://learn-automation.com/maven-no-compiler-is-provided-in-this-environment-selenium/

Make sure you have %JAVA_HOME% set by typing echo %JAVA_HOME% in Command Prompt. If you don't have that set, then you need to go add your Java path to Window's Environmental Variables.

I resolved this issue by providing JAVA_HOME in my enviroment variables and restarted intellij

you can follow any of one from given below.
Project--properties--java build path--jre system library--edit--add library path as JDK
Window preference--java--installed JRE--JRE system library--add library and provide path to JDK folder
You will have to instruct eclipse to use JDK as build/compile source in some ways if it's configured to point to jre instead For default compiler

If none of the above helped still You are facing the same issue means you may have misconfigurations in your Custom Run/Debug Configurations.
In My case I am using a Custom maven run configuration.
There the JRE is pointed earlier. Once I changed it to JRK it worked as expected.

I had a problem with Eclipse Neon where the workspace default did not actually change even though I added the correct location under Preferences->Java->Installed JREs. This was in a new workspace I created to work on a code branch; it was originally set to the JRE location rather than the JDK. Yet even after changing the preferences, I could build with the command line, yet building in Eclipse produced the no compiler error. Please see
Maven Package Compilation Error
for my answer on which Eclipse configuration file(s) had to be manually edited to make Eclipse recognize the correct workspace default. I still have no idea why the preferences setting did not carry through to the new workspace's configuration.

No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?

I'm compiling a project in Eclipse using m2eclipse. I set the JDK path in Eclipse like this:
Windows-->preferences-->installed jres--> jdk1.7.xx path
But this is showing an error
[ERROR] COMPILATION ERROR :
[INFO] -------------------------------------------------------------
[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?
[INFO] 1 error
[INFO] -------------------------------------------------------------
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 1.424s
[INFO] Finished at: Tue Oct 29 15:21:01 IST 2013
[INFO] Final Memory: 5M/15M
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler- plugin:3.1:compile (default-compile) on project TEST-WEB: Compilation failure
[ERROR] No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?

On your Eclipse IDE, go into Window > Preferences > Java > Installed JREs > and check your installed JREs. You should have an entry with a JDK there.
Select the Execution Env as show below. Click OK
Then Right-Click on your Project -> Maven -> Update Project
Additionally, you may have to change Maven JRE (see #jlars62 answer) which is as follows. Goto Run -> Run Configurations, selecting the Maven Build I was running (from the left panel). Then, I clicked the JRE tab and selected the option Workspace default JRE

Set the JAVA_HOME environment variable to the JDK root folder - required if you run command line or maven (mvn).
(Search google for JAVA_HOME for more info)
In project properties in section Java Compiler select required JDK - if you run directly from eclipse

For me, it is exactly what the maven of eclipse complains
So, I press Edit button and change path to the JDK Folder, then clean project and everything starts to work

For me, nothing worked until I made this change to my pom.xml:
<build>
...
<plugins>
...
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<fork>true</fork>
<executable>C:\Program Files\Java\jdk1.7.0_45\bin\javac.exe</executable>
</configuration>
</plugin>
</plugins>
</build>
Other Notes
I could see that m2e was executing in a JRE, not the JDK. Nothing I did changed this, including adding this to the eclipse.ini:
-vm
C:\Program Files\Java\jdk1.7.0_45\bin\javaw.exe
In the end I never got m2e to execute in a JDK, but setting the Java compiler explicitly (as above) did the trick.

In my case it was solved by doing this:
Go to your 'Runtime Configuration' and configure your JRE to an JDK.
I copied answer just in case it is deleted for some reason, but the source is here

I was getting this error when trying to do a maven build from within eclipse.
For me, the answer was going to Run -> Run Configurations, selecting the Maven Build I was running (from the left panel). Then, I clicked the JRE tab and selected the option Workspace default JRE

Go to windows -> Preferences -> Java -> Installed JREs
may be jre is already added
click on Add -> Standard VM -> Next -> Directory
and browse for the JDK
in my case path was C:\Program Files\Java\jdk1.8.0_111
then Click on finish.
you will see window like this
select JDK -> Apply -> Ok
And You are done.

I got same issue and i just add JAVA_HOME to environment variables.
If you are using eclipse, just refer https://stackoverflow.com/a/21279068/6097074
If you are using intellij, just after adding JAVA_HOME open command prompt from project directory and run mvn clean install(don't use intellij terminal).

I tried all of the above, however, still getting the same error message.
In my case an actual JRE was incorrectly used as JRE System Library in the project-specific build path which was obviously overriding all those other settings discussed here.
If that is so in your case try the following:
Open the project-specific libraries of the Java Build Path: Right-click "Project > Build Path > Configure Build Path..." and select "Libraries" tab.
Select the "JRE System Library" entry and hit "Remove".
Hit "Add Library...".
A wizard pops up. Select "JRE System Library" and hit "Next >".
Now select the correct JDK (in my case "Workspace default JRE", which I
configured using a JDK).
Close wizard by hitting "Finish".
Close "Properties" dialog by hitting "OK".

An alternative if jaipster's answer does not work is to go to:
Window > Preferences > Java > Installed JREs
Then to edit the jre so that it points to the jdk and not the jre (the jre home filed in the jre package editor)
That worked for me.

I faced the same issue while trying to build a jar file of my project application using mvn clean install, though the application was working fine while running from Eclipse.
The issue was, indeed too naive, that I had not set the JAVA_HOME environment variable. All I had to do is set JAVA_HOME environment variable to JDK directory, make sure it is not till "\bin" and without semi-colon ";".
How I understood it is as:
The application worked fine in Eclipse as JRE System Library was referring to JRE inside the JDK folder instead of external JRE folder without JDK. [As explained very well in other answers]
This configuration does not apply to maven command that we run on command prompt. It will still look for JAVA_HOME variable to access the JRE System library and when it is not found it refers to external JRE folder without JDK.

If you are running the Maven command from cmd, make sure you set the jdk path before running the command. In my case, I have created a .bat file containing the following:
set JAVA_HOME=C:\Program Files\Java\jdk1.8.0_60
start cmd.exe /k "cd c:\aem_proj\sis\aau"

My answer pertains to the Eclipse in Windows environment.
I went to Preferences --> Java --> Installed JREs
I did NOT see the JDK in here. I only saw the JRE here.
So I added the JDK and then unchecked the JRE. Then checked JDK.
Then I ran the POM file using Run Configurations. Choose the tab JRE and select the option "Workspace Default..."
Here are the images

There are several options to specify.
Steps:
Right on project in project explorer
Go to Run-> Run Configuration -> Click Maven Build -> Click on your build config/or create a new config.
You will see the window as the given snapshot below, click on JRE tab there.
You see you have 3 options 1) Workspace Default JRE 2)Execution Environment 3)Alternate JRE
1) Workspace Default JRE is set from 'Window' menu on the top -> Preferences -> Java -> Installed JREs -Here you can add your jdk
2) Execution Environment jdk can be set in pom.xml as mentioned by #ksnortum
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<fork>true</fork>
<executable>C:\Program Files\Java\jdk1.7.0_45\bin\javac.exe</executable>
</configuration>
</plugin>
</plugins>
3) Alternate JRE can be used to select a jdk from your directory

Problem statement = No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK? intellij
Solution
Please set the Environment variable like below to solve the issue
Variable name : JAVA_HOME
Variable Value : C:\Program Files\Java\jdk1.8.0_202
Variable name : M2_HOME
Variable Value : C:\Program Files\apache-maven-3.6.0
Moreover, Add Java and maven path in "System Variables" like below:
C:\Program Files\Java\jdk1.8.0_202\bin
C:\Program Files\apache-maven-3.6.0\bin

Though the question is about the error with Eclipse setup but thought an answer of fixing this error with IntelliJ and Windows 10 setup may also be helpful here.
1. Go to File --> Settings --> Build, Execution, Deployment --> Build Tools --> Maven --> Importing
2. Set JDK for Importer as shown below to JAVA_HOME
Also JAVA_HOME should be set to JDK path at Environment Variables --> System variables and also add %JAVA_HOME%\bin to Path System variables

For me the JRE was in the PATH environment variable before the JDK path
C:\ProgramData\Oracle\Java\javapath
C:\env\jdk1.8.0_151\bin
So I removed 1. Probably swapping them would fix it too.

There is another possible answer to this question, and I may be the only person foolish enough to have stumbled upon this, but I think it's worth adding, since none of the other answers applied as I already had those settings correct.
When you install a JDK, the installer asks you where you want to install the files. By default, on Windows, this is something like C:\Program Files\Java\jdk1.8.0_74 (or whatever version you are installing).
It then asks you for a directory to install the JRE to, which by default is something like C:\Program Files\Java\jre1.8.0_74.
Note that one is jdk1.8.0_74 and the other is jre1.8.0_74
I was rushing things, and thinking the installer was asking me the same question twice, set both my JDK and JRE install locations to D:\devtools\jdk\jdk1.8.0_74, resulting in the installer overwriting the JDK with the JRE. This resulted in (among other things) a missing javac.exe in my JDK bin, and the same error the OP reported here in all my maven builds.

I got a solution.
The most common solution for this problem is to change jdk location as my Installed JREs instead of the JRE location but that did not solve my problem this one time.
So I did the below to solve the problem.
Expand the Installed JREs tab and you will find a Execution environments tab.
Click on your favourite execution environment. In my case it was JAVASE-1.8. There it shows 2 options. JDK and JRE. Select JDK there and the problem is solved.

I tried most of the answers without success.
What worked for me was (after following https://stackoverflow.com/a/21279068/2408893):
right click on project -> Properties
select Java Build Path
select the JRE System Library
click edit
In execution environment select a jdk
click Finish
build and run

I did the following change and it worked for me.Hope it helps someone.

I just wasted 3 hours with this problem until I managed to make it work.
I had this error in the Eclipse Terminal when issuing a mvn compile command:
No compiler is provided in this environment. Perhaps you are running on a JRE rather than a JDK?
So I read here that I have to make a new system variable called JAVA_HOME and make it point towards the jdk installation folder. However this generated another error:
Source option 1.5 is no longer supported. Use 1.6 or later
Couldn't find a fix for this one so...
So the fix to make it all go away is install Java SE Development Kit 8!
I was using 9 thinking that if it's the latest it must be better...
Anyway...
Uninstall all java versions from your computer
Install JDK8 from here:
http://www.oracle.com/technetwork/java/javase/downloads/jdk8-downloads-2133151.html
Then define the JAVA_HOME system environmental value - tutorial here:
https://docs.oracle.com/cd/E19509-01/820-3208/inst_cli_jdk_javahome_t/
Restart Eclipse and enjoy! (at least that's what I did)
Hoping this spares some poor wanderer of some trouble.

In my case I had system variable path has "C:\ProgramData\Oracle\Java\javapath" location.
In "C:\ProgramData\Oracle\Java\javapath" location java, javaw only there. So I am getting the same error.
Once I removed all files in "C:\ProgramData\Oracle\Java\javapath" folder my error got resolved.

i faced the same issue, the mistake i made was i added jre path only in the path var,not jdk path .When jdk path was added to path and build the maven project its working perfect .Thanks all

Try this.
<build>
...
<plugins>
...
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<fork>true</fork>
<executable> path to jdk \bin\javac.exe</executable>
</configuration>
</plugin>
</plugins>
</build>

Add new JRE definition (select path JDK), worked for me.
http://help.eclipse.org/neon/index.jsp?topic=%2Forg.eclipse.jdt.doc.user%2Ftasks%2Ftask-add_new_jre.htm

I was getting the same error when I created a new EC2 ubuntu 16.04 instance with Java already installed on it and while running mvn clean package, I encountered this issue and the below solution worked for me.
If you are working on an Ubuntu server, then you can try installing Java again and for that you can use this answer How to install the JDK on Ubuntu Linux

In Windows 7 - 64 bit, there is a permissions problem which prevents the installer from unpacking the file C:\Program Files\Java\jdk1.6.xx\lib\tools.jar into your local. This jar file is what maven-compiler-plugin version 3.x uses instead of the usual javac
Solution: Run, as an administrator, the Java JDK installer! And make sure the tools.jar is sitting in the C:\Program Files\Java\jdk1.6.xx\lib\
In case you are using m2e maven integration plugin, you want to see the file is visible to Eclipse via the following steps inside Eclipse:
Go to Window -> Preferences -> Java -> installed JREs
Select the JDK you are using (C:\Program Files\Java\jdk1.6.xx)
Press Edit to see the list of jars including tools.jar, OR you can add it as Add External JAR
Then configure the maven run through these steps:
Run->Run configurations->Fill in Name, Base directory and Goals.
Then in the same window move to the JRE tab and point to the JDK \jdk1.6.xx\

In Linux, doing a docker example, I must not have had the JDK installed just the JRE. After sudo apt install openjdk-8-jdk and setting JAVA_HOME in profile and adding JAVA_HOME/bin to the path, it built!

For me, I had upgraded to Big Sur Mac OS and I had to remove this and then it worked fine.
sudo rm -fr /Library/Internet\ Plug-Ins/JavaAppletPlugin.plugin

Java project in Eclipse: The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files

I am getting the following error after importing a project in Eclipse:
The type java.lang.Object cannot be resolved. It is indirectly referenced from required .class files
However, I have set the path as C:\Program Files\Java\jdk1.6.0_41 in Eclipse Kepler, through Window » Preferences » Java » Installed JREs.

This is an annoying Eclipse Bug which seems to bite now and then. See http://dev-answers.blogspot.de/2009/06/eclipse-build-errors-javalangobject.html for a possible solution, otherwise try the following;
Close the project and reopen it.
Clean the project (It will rebuild the buildpath hence reconfiguring with the JDK libraries)
OR
Delete and Re-import the project and if necessary do the above steps again.
The better cure is to try NetBeans instead of Eclipse :-)

The following steps could help:
Right-click on project » Properties » Java Build Path
Select Libraries tab
Find the JRE System Library and remove it
Click Add Library... button at right side » Add the JRE System Library (Workspace default JRE)

This happened to me when I imported a Java 1.8 project from Eclipse Luna into Eclipse Kepler.
Right click on project > Build path > configure build path...
Select the Libraries tab, you should see the Java 1.8 jre with an error
Select the java 1.8 jre and click the Remove button
Add Library... > JRE System Library > Next > workspace default > Finish
Click OK to close the properties window
Go to the project menu > Clean... > OK
Et voilà, that worked for me.

Here is how I solved it:
In Java-ADT: Windows - Preference - Java - Installed JREs
Just add another JRE, pointing to the 'jre' folder under your JDK folder. (jre is included in the jdk). Make sure you chose the new jre.

Object class is the base class for all the classes in java, if you are missing this it means you don't have the jdk libs in your buildpath. I don't know much about Kepler but you need to make sure it points to a correct jdk for compilation and a correct jre for running your java apps.
However I have set the path as C:\Program Files\Java\jdk1.6.0_41 from
eclipse Kepler toolbar->windows->preferences->java->installed jre
You are trying to point jdk instead of jre in your preferences. toolbar->windows->preferences->java->installed jre should point to a jre and not jdk.

Have you installed a different version JRE after , while using previous version of JRE in Eclipse .
if Not than :
Right click on your project -> Build Path -> Configure Build Path
Go to 'Libraries' tab
Add Library -> JRE System Library -> Next -> Workspace default JRE (or you can Choose Alternate JRE form your System) -> Finish
if Yes than .
Right click on your project -> Build Path -> Configure Build Path
Go to 'Libraries' tab
Remove Previous Version
Add Library -> JRE System Library -> Next -> Workspace default JRE (or you can Choose Alternate JRE from your System) -> Finish

No amount of cleaning, closing/reopening the project&IDE, removing/adding the JRE in build path worked for me.
The solution I found was to remove the project from Eclipse (not from disk), remove the project's Eclipse files from the disk, and import into Eclipse again. That worked.
It is even faster if you are using Maven:
Close Eclipse (no need to remove the project)
Run mvn clean eclipse:clean eclipse:eclipse
Open Eclipse. Your project is still present and the problem should be gone.

This seems to be an Eclipse bug, though restarting Eclipse worked great for me, hope this helps somebody else too.
Edit: the next time I had this problem the solution above did not work - the problem was that the imported project I had - had the wrong java runtime set - which was not present (I had java 8 in my JRE present, but the project imported was set to Java 11, so I had to change the project java version to 8. Alternative would be to add more JRE's in the Eclipse preferences - if the project really needs a newer JRE to work)

None of the other answers worked for me. But doing this did:
Right click the project in the package explorer.
Source > Clean up...
Next > Finish
When I did this Eclipse added an import into one of my classes. I think this occurred because I saved my project with a missing import, probably rushing to get home after work.

Right click on project -->Show in Navigator
In navigator view you can see .classpath file, do delete this file and build the project. This worked for me.
PS. If you have integrated you eclipse project with some version control like perfoce/svn , then unlinking the project before you delete the .classpath will be helpful.

Another problem could be that the Android Project Build Target is not set.
Right-click the project
Choose Properties
Click Android
Tick the appropriate Project Build Target
Apply | OK

I was facing this issue with play-java application on eclipse after adding a controller,
I removed and reinstalled JRE through build path and then removed and imported my project which solved this issue automatically.
Thanks gyro.

What solved my problem was to
1) Install the jdk under directory with no spaces:
C:/Java
Instead of
C:/Program Files/Java
This is a known issue in Windows. I fixed JAVA_HOME as well
2) I java 7 and java 8 on my laptop. So I defined the jvm using eclipse.ini. This is not a mandatory step if you don't have -vm entry in your eclipse.ini. I updated:
C:/Java/jdk1.7.0_79/jre/bin/javaw.exe
Instead of:
C:/Java/jdk1.7.0_79/bin/javaw.exe
Good luck

I had the similar problem. It was a maven project with the following snippet of pom.xml.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<release>9</release>
</configuration>
</plugin>
</plugins>
</build>
I had to change the following.
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<release>11</release>
</configuration>
</plugin>
</plugins>
</build>
If you have already installed JDK 11 and working with java 9 or java 10 as maven compiler, eclipse can not detect. Hence change the release to 11 or the actual installed version of JDK.

I had same problem in eclipse windows that I couldn't added dependant .class files from the JNI.
In order resolve the same, I ported all the code to NetBeans IDE.
Can not add all the classes files from the JNI/JNA folder in Eclipse (JAVA, Windows 7)

While we are working with tomcat 6 and jdk 1.8 versions, some of the features will not work and this error you are getting is one. you need to change the jdk version to stable version(preferable jdk 1.6 or jdk 1.8_65) in eclipse to resolve this error.
in eclipse
step 1: properties -> java build path -> jre system library(remove)
step 2: add -> jre system library -> alternate jre -> installed jre -> add -> Standard VM -> (in jre home, place jdk path) -> finish
now clean and check the project

I got this error because I have installed "Eclipse IDE for Enterprise Java Developers", I uninstalled this and installed "Eclipse IDE for Java Developers". Problem solved for me.

It's working for me after unchecking 'User '--releae option' in eclipse Java-compiler
In eclipse step 1: properties -> java Complier -> uchecking 'User '--releae option' option -> finish
Java version 13.0.1
Eclipse version : Eclipse IDE for Enterprise Java Developers.

However I have set the path as C:\Program Files\Java\jdk1.6.0_41 from eclipse Kepler toolbar->windows->preferences->java->installed jre
If you have already added JRE and still showing error. try follow
right click on your project
project->build path-> configure build path -> java build path -> libraries tab -> select JRE system library and click edit button -> If alternative JRE is selected choose workspace default JRE.
this is how my error gone.

Happend to me after I've installed some updates in eclipse but forgot to restart afterwards. So maybe restarting eclipse might help.

However trivial this might be, check your Java installation. For me, rt.jar was missing.
I found this after fiddling for half a day with Eclipse settings and getting nowhere.
Desperate, I finally decided to try compiling the project from the command line. I wasn't expecting to see anything wrong since I thought it's an Eclipse issue but to my astonishment I saw this:
Error occurred during initialization of VM
java/lang/NoClassDefFoundError: java/lang/Object
I don't know what happened to my Java installation and where did rt.jar go. Anyway this comes as a reminder to go through the fail checklist and tick all the boxes no matter how unbelievable they are. It would have saved me a lot of time.

Right click on project, select Maven -> Update project.
That should solve the issue.

In my case it was a big modular project and the 'red X' was showing only in the parent project.
I went to the parent project
Properties -> Built Path
a removed the JRE Library there, just that, no JRE Library on the parent project anymore.

None of these solutions worked for me. In my case the problem was that I had some Java code producing .java files and I had accidentally created a file called Class.java (content doesn't seem to matter). Removing the file fixed the problem.

sometimes this error happened after updating JAVA. if so go to eclipse.ini file in the same folder where eclipse existed. then change the line under -vm keyward to the new path of jre/bin folder to get the path go to programfiles -> java -> jre latest version -> bin folder copy the path and replace in line under -vm keyword.

This error message occurs when a class/java-project is unable to resolve correct JDK libraries. Say, in my primary Project A, I was getting this error. This Project A had a maven dependency for a project B. Project B pointed to JDK-11. Project A pointed to JDK-9
Correction I did : Made Project also point to JDK-11. It resolved the issue for me

For Gradle users, use eclipse plugin. I'm not using eclipse directly but jdtls on Neovim. This solves the issue for me.
build.gradle
plugins {
id 'java'
id 'eclipse'
}
Then run
gradle cleanEclipse eclipse

Unable to use old java projects in new eclipse installation

I did an upgrade of my windows OS and restored my eclipse workspace from my backup. Now, when I try to open any of the older projects, they complain with a message:
Unbound classpath container: 'JRE System Library [jre6]' in project <ProjectName>
When I looked around, I found pages which suggest that I change the JRE version for the project. However, I have about 50 projects in this workspace and do not want to change the value for each of them.
Any suggestions would be welcome.
Thanks and regards,
Karthick S.

You should add a new JRE and name it [jre6] (or rename your current JRE). That will prevent you from changing manually your 50 projects.
Window -> Preferences -> Java -> Installed JREs -> Add...

The problem is that if you backed up the eclipse project files, then these contain information regarding paths to your JRE or JDK install and any external jars (specific to your last install). There are 2 files that you can edit with any text editor to fix this problem .classpath and .project.
Other option would be to delete the classpath and project files and try to import the project as java project using File > Import.