We Keep Coding

Eclipse Oxygen - The project was not built since its build path is incomplete

I just installed Eclipse Oxygen and tried to open an existing project into the workbench but I get this error:
The project was not built since its build path is incomplete. Cannot
find the class file for java.lang.Object. Fix the build path then try
building this project
I tried right clicking on the project - went to Properties - Java Build Path - Libraries - Add Library - JRE System Library and selected Workbench default JRE (jre1.8.0_60).
I then cleaned and rebuilt the project but it then causes more errors to come up like:
ActionBar cannot be resolved to a type
Activity cannot be resolved to a variable
AdapterView cannot be resolved to a type
ArrayAdapter cannot be resolved to a type

Here is what made the error disappear for me:
Close eclipse, open up a terminal window and run:
$ mvn clean eclipse:clean eclipse:eclipse

Are you using Maven? If so,
Right-click on the project, Build Path and go to Configure Build Path
Click the libraries tab. If Maven dependencies are not in the list, you need to add it.
Close the dialog.
To add it:
Right-click on the project, Maven → Disable Maven Nature
Right-click on the project, Configure → Convert to Maven Project.
And then clean
Edit 1:
If that doesn't resolve the issue try right-clicking on your project and select properties. Select Java Build Path → Library tab. Look for a JVM. If it's not there, click to add Library and add the default JVM. If VM is there, click edit and select the default JVM. Hopefully, that works.
Edit 2:
You can also try going into the folder where you have all your projects and delete the .metadata for eclipse (be aware that you'll have to re-import all the projects afterwards! Also all the environment settings you've set would also have to be redone). After it was deleted just import the project again, and hopefully, it works.

In Eclipse, Right click Project -> Maven -> Update Project. It fixed errors in my project.

I'm also using Eclipse Oxygen, migrated from Mars. I faced the same error. I deleted .metadata, .recommenders folders and added projects from archive and issue is solved. I also use Android Studio but i like Eclipse much more.

At my system the Java Runtime JAR file jrt-fs.jar was not found because it was in the wrong directory. This file should be located in the "lib" subfolder. If you installed Java at "C:\Temp\java" the file should be here at C:\Temp\java\lib\jrt-fs.jar .
These are the steps to make jrt-fs.jar available to Eclipse:
Window / Preferences -> the "Preferences" Window opens
Select in the left menu: Java / Installed JREs
Press the [Add...] Button -> A window opens
Select "Standard VM" - The window "JRE Definition" opens.
Enter your path information:
JRE home = "C:\Temp\java"
JRE name = "MyJRE"
Select [Add External JARs...] to link the jrt-fs.jar
JRE system libaries: "C:\Temp\java\lib\jrt-fs.jar"
It worked for me with OpenJDK12 and Eclipse 2019-09 (4.13.0).
Eclipse reported me this error:
The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project

I had faced this problem. I added the C:\Users\Office 2\android-sdks\platforms\android-19\android.jar to the Java Build Path's Library. And the project started to run again.
The problem occurred due to my carelessness. Yesterday night I was updating the Android SDK, and at the same time I tried to run the project, while the SDK Manager was uncompressing the system image. The Project couldn't start and the error occurred.
I tried all the methods given by others. But nothing worked. It solved when I added the android.jar to the library.
I guessed it that android library is missing. not the Java, when I saw the errors only at the android methods and imports. But when I read the posts, I got confused and wasted some time trying wrong way.

I had faced the same issue and tried different solutions, I have reinstalled my JDK 11 and restarted the machine, after that the issue gets resolved.

I got this out of the blue in a workspace that was working properly before. This problem seems to indicate that the project configuration somehow got corrupted.
Restarting Eclipse didn't help, but in the same vein as the answers dealing with Maven, regenerating the Eclipse project config with:
./gradle eclipse
or
./gradlew eclipse
if you use the wrapper, solved this problem for me.

I have similar issue when importing Spring Boot, jdk 11 (using
inside docker) project to Eclipse 2019 (2021), in Ubuntu, instead when
importing to Inteelij IDEA Community or NetBeans IDEs they do
not produce the same set of after-import errors as in Eclipse.
The Spring Boot is multimodule maven projects and two child
modules give such 2 "problems" in appropriate problems tab:
The project was not built since its build path is incomplete.
Cannot find the class file for java.lang.Object. Fix the build
path then try building this project
Next 2 errors are produced in two classes of aforementioned
maven modules:
The type java.lang.Object cannot be resolved. It is
indirectly referenced from required .class files
Manipulation with adding JDK 11 to submodules buildpath
just leads to the thousands of problems. Also it is
got when I use Eclipse-File-Maven-Update.
Moreover when I try to edit most of existing classes or add new ones
I got red underline that tells
Implicit super constructor Object() is undefined for default
constructor. Must define an explicit constructor
. So almost no opportunity to use Eclipse
even at prebuild stage as docker-compose should run build and
run. Indeed I noted that such issue is produced just when project
also uses modules (module-info files introduced in java9).
When I import project on jdk 8 (even not installed on
system), or even on jdk11 without module-info files all
is fine in Eclipse after import.
Another difference is that of when I use problem old no module
project the Build Path is composed with jre environment 8 and
maven dependency items, but when using
"module-info" project the Build path contains -module path,
and -classpath. So I even do not know where to add jre 11,
indeed adding does not resolve issue, just make more errors.
So what is the resolution of the case??? What settings to do
in Eclipse?

Unable to find package java.lang in classpath or bootclasspath with ant [duplicate]

I'm getting this error
Error:java: Fatal Error: Unable to find package java.lang in classpath or bootclasspath
in IntelliJ when I try to build/compile any project. Something that should be stated here is that NetBeans, Eclipse and even the javac command line can compile, build, and execute the same project without errors. This is why I suspect that the problem lies with IntelliJ, all other IDEs work well.
In IntelliJ I already:
Restarted, reinstalled
Invalidate Caches / restarted
Deleted / readded the JDK in Project JDK
Deleted / readded the JDK in Platform Settings
Rebuild / recompile
In Windows I already:
Deleted / Reinstalled Java SDK
Deleted / Readded the JAVA_HOME, PATH and CLASSPATH on System Variables
Tried the above on User Variables
Deleted and reinstalled IntelliJ IDEA
I already seached for issues like this on the Internet, here on Stack Overflow I found:
Question #1 | Question #2 | Question #3 | Question #4 | Question #5
And 30+ sites, and tried every answer...
Here you can see my IntelliJ Project Structure the last time that I tried to build/compile
I was using Java 1.8 when I got this error, after some hours, I installed Java 1.7 and the project worked fine. Maybe IntelliJ doesn't support Java 1.8?
Anyway, it would be great if anyone knew a way to make Java 1.8 work with IntelliJ.

I just spent quite few hours on this and found a solution which might work for you as well. IntelliJ seems to have a bug which expects the JDK to be in a different directory than is specified. I followed these steps:
open intelliJ, click help -> show log in explorer
modify build-log/build-log.xml and change <priority value="info" /> to <priority value="debug" />, you may have to run the editor as an administrator
run the compilation which fails with "Error:java: Fatal Error: Unable to find..."
open build-log/build.log and search for rt.jar, you should find it in a block with a set of other JRE libraries and the directory which points to the file should be wrong
In my case the JDK is included in D:\Development\software\jdk1.8.0_20, while the log points to C:\Users\Vladimir\Development\software\jdk1.8.0_20
I fixed the issue by copying my JRE to the place which is expected in the log. And just like in your case this seems to only happen with JDK 1.8.

The problem comes from IntelliJ bug (existing at least in version 14).
It happens when your JDK directory is under the user profile directory. For example, JDK located in this directory (for Windows):
C:\Users\myuser\jdk1.8.0_20
will be stored in IntelliJ internal configuration (file 'jdk.table.xml') as:
$USER_HOME$\jdk1.8.0_20
But your %USER_PROFILE% environment variable could point at some other (non default) location. Then IntelliJ will look at the wrong directory.
Possible fix:
Install your JDK at different directory, which is outside your profile directory. Like:
C:\Programs\jdk1.8.0_20
Then register this JDK for use in your IntelliJ project settings.

I encountered this on Arch Linux 4.16.13 with IntelliJ 2018.1.4 after importing a Java project using Gradle. I made sure that there is a registered JDK in "Project Settings" -> "Project" but IntelliJ was unable to find the classes from the JDK, java.util.List for example.
The solution was to add a new JDK entry at the same path as the existing JDK (/usr/lib/jvm/java-8-openjdk in my case). This will cause IntelliJ to put the files under jre onto the classpath whereas with the old JDK entry, only the files under lib were on the classpath.

Had the same problem. Simple fix to others in case the other answers are complex.
Go to File -> Project Structure
Under Project SDK, choose new and add another JDK.
The default use in my case was 1.8 that was of build 181. I choose the 1.8.0_192 I had recently downloaded.
After applying, the project loads itself.
When I re-ran the test, it works!

If this problem occurs when importing a project in netbeans then try to create a new project then check the properties of your new created project and match those properties with the project that you imported in my case there was a difference between target of android package version.

From what I understood, debugging for hours, the problem is with the location where the jdk1.8 gets installed(/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home), instead of under System/Library).
So the following has to be done to fix in intellij
1. For an existing project, right click and select module settings, and SDK and add 1.8 as a version.
2. Using a terminal go to ~/Library/Preferences//options/. Remove the old JDK specific lines in jdk.table.xml. Update the default version in project.default.xml
Clean you project in intellij and build. It should use the new jdk and sync.

eclipse external tools configurations -> referenced library in classpath does not exist: org.eclipse.swt

After updating to the latest eclipse mars release
Version: Mars Release Candidate 1 (4.5.0RC1)
Build id: 20150521-1252
I am not able to start any Ant Script. It always results in the following error:
First I checked if the path is really correct, and made sure that the specific jar org.eclipse.swt.win32.win32.x86_64_3.104.0.v20150513-1901.jar exists at the given location, which it does. After some digging I noticed the following within the external tools configurations:
Somehow I think eclipse is not able to resolve the classpath with the given '%20' tag within the url to the library. Usually there is just a blank. Restoring the defaults always fills in the '%20' for this specific library.
So I created a copy of eclipse at a location without blanks and all works fine again.
Unfortunatly I would prefer keeping the location at it is, so is there a way to correctly resolve the classpath for Additional Tasks & Support?

There is one other "fix" that's basically an easier workaround.
If you go to your Ant build configuration (under External Tools, then highlight your configuration and select the JRE tab) and change from running an external JRE to the top button, that is, "Run in the same JRE as the workspace", this will make it work.

This is a known bug in Eclipse Mars:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=470390
Update: Eclipse 4.5.1 was released on October the 2nd and the bug has been fixed. An Eclipse update will resolve this issue.

I resolved this by moving C:\Program Files\eclipse to C:\eclipse
Answer also found here, Eclipse Mars: ANT Task references missing SWT library

Cannot build jhipster project in eclipse

I cannot build a simple project (just created with yo jhipster) in Eclipse.
I'm getting the error:
Maven Dependency Problem
Missing artifact com.sun:tools:jar:1.6
Thare are other errors too but i think this is the one that is causing problems.
I can compile and run the same project from command line with mvn spring-boot:run
I googled for the error and found lots of solutions but unfortunately none worked.
If i check Eclipse configuration i can see that java.home points to C:\Program Files (x86)\Java\jre7 no matter what i do.
I tried to edit the eclipse.ini file adding -vm C:\Progra~1\Java\jdk1.7.0_51\bin\javaw.exe
I also double checked that my workspace and project are using a Jdk and not a Jre Vm.
Can someone please point me to the right direction please?
Thanks!

I had the same issue before... you are probably running your Eclipse with a JRE rather than a JDK. The sun tools jar is actually part of the latest JDK, and doesn't necessarily need to be inferred directly in your project.
See my comments, issue #1, in the attached link:
JHipster Eclipse project running out of memory in "main"

Try with STS and everything works. Seems to be an issue with your eclispe

I've imported the sample jhipster in Eclise (without STS) and everything was OK, after installing the maven dependencies.
To run the project, run as an application and search for the Application (com.mycompany.myapp.Application)

java.lang.Object cannot be resolved in Eclipse

When I installed the latest installment in Mac OSX - the Mountain Lion - I experienced some problems getting Eclipse to work I also lost most of my Android developer files (but I still have my projects). I suspect this is due to the choice of removing the /Developer and move the XCode and other Apple developer tools (I placed my Android tools here).
I have now installed the latest version of Eclipse and the problem still seems to be around. There are errors in all my projects and I get an error message prompting:
The type java.lang.Object cannot be resolved. It is indirectly referenced
from required .class files
I tried to check the Java class-path both in Eclipse and in my terminal and these seems to be OK. java and javac both run in my terminal and there is a valid path to the java source files in Eclipse (Under Preferences, Java, Installed JREs). That being said I'm not an expert in Eclipse so there may be that I have misunderstood how this problem ought to be solved. Anyone here with similar problems or who know the cure?

Make sure that you have a valid JRE or JDK defined in the Java Build Path of your project. Right-click on your project, select Properties... and then Java Build Path.

I had this problem moving a Maven project from Eclipse to RAD. I had a JSP file that worked in Tomcat and JBoss, but threw a NullPointerException in WebSphere on the form definition during the compile.
Anyway, after transforming the Maven project into an Ant project (mvn ant:ant), I imported the Ant project into RAD and got this error. The fix:
Open the Java Build Path, selecting the Libraries tab.
Find the JRE System Library and remove it.
Add the JRE System Library.
Goofy, but it works. It must reset some property in a file. I don't know if the problem is the older version of Eclipse or RAD.

After updating my Android SDK to make Appcelerator Titanium happy, I started getting "java.lang.Object cannot be resolved" for my Android projects in (non-Titanium) Eclipse.
I updated all dependencies in Eclipse, and the error healed after a restart of Eclipse.

I had that error almost every time I launched Eclipse for the first time; if I close and then re-open Eclipse, the error is gone.
I found this solution useful, though (I've copied here to protect the link, credit goes to the original author):
In Eclipse go to Windows -> Preferences -> Java -> Installed JREs.
Select the currently active JRE/JDK and press the Edit button.
Select the rt.jar and change its position in the list of JRE system libraries (e.g. press the Up button once).
Confirm all changes, clean and rebuild the workspace.
The next time you face the problem reposition the rt.jar again (or reset the order by pressing the Restore Default button).

please select your installed system jre version from java build path.

Try the following and problem will go away
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.

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

I got this error and what I had to do was remove the JRE from the Window/Preferences/Java/Installed JREs and re-add it. This somehow cleared up eclipse's cache and rebuilt the project successfully. To get rid of the error in the file-editor I also had to close it and open the file once again.

My problem was that I had in Eclipse: Window / Preferences... and then in the tree on the left Java / Installed JREs: C:\Program Files\Java\jre7
I changed to: c:\Program Files (x86)\Java\jre7
It solved my problem.

I had the same issue and none of the above solutions worked for me.
Then I realized than the library (libs) folder was missing in the project. Once i added the libs folder and the corresponding Jar file, the issue was resolved..

If your project specific (or if not applicable, workspace default) JDK/JRE is being referenced correctly and you've just begun to get this issue out of the blue: restart Eclipse.
Unfortunately, "restart Eclipse" is one of the standard troubleshooting steps when a project won't build. Eclipse even has a dedicated entry under the File menu.

I had to add the JDK under the build path. After adding the correct build path it worked.

I just had to restart eclipse, and the error went away. Strange.

I solved this by pointing my eclipse to the jre available in jdk.

This error caused by invalid sdk is pointing in your project.properties file of your project.
project.properties -> target=android-19 . change to version which is installed in your eclipse.The error will be gone.

I had the same issue after moving from JRE7 to JDK7. Finally I had to remove the JRE7 configuration from the Eclipse preferences and then add the following two lines to the eclipse.ini file.
-vm
C:\Program Files\Java\jdk1.7.0_55\bin\javaw.exe

I had this problem, and I understood that Eclipse has automatically imported a core reference, instead of the reference for the project I needed.
Deleted the import, and rearranged it, and everything worked fine.

Same problem facing Me
Project->properties->Android
And select the api level and also go in java build path and check some external jar file path if we already add in it.update the jar file path

On "The type java.lang.Object cannot be resolved. It is indirectly referenced
from required .class files":
I found my project had 2 meta-inf.java files in 2 different directories with the same 'module ' on line one (a copy/paste error).
Once this was corrected, I cleared the meta-inf.java file with the issue, rebuilding it line by line, guided by Eclipse, until I had a working module configuration.