I recently installed visual studio on my Ubuntu Linux machine. I also installed Java on my Ubuntu system but I keep getting "Classpath is incomplete" warning" anytime I run my a java code as well as Java implicit super constructor not defined whenever I run my code. I would like an easy to understand solution on how to fix this particular problem.
Edit:
I tried this exact same code on my Mac and it doesn't give me the "Java implicit super Constructor not defined" warning.
If you getting that error message you can try below steps:-
1) Open Command Palette (Ctrl+Shift+P) and typing the command Java: Configure Java Runtime.
2) Scroll down to install JDK, Choose the version(I chose latest one), download it install it (during installation you get the option to add the path to java_home variable choose it) ,after clicking finish on set up click reload on vs code.
This has already been answered at Visual Studio Code - Java Classpath is incomplete. Only syntax errors will be reported
Visual studio code does not support java right out of the box without a maven or eclipse project defining the classpath. Best solution in my opinion is to use eclipse or intellij or any other java IDE instead of VSCode.
The constructor error you're getting is because your class isn't starting with a capital letters. Classes should always start with a capital letter.
Java naming conventions: http://www.oracle.com/technetwork/java/codeconventions-135099.html
Related
I recently downloaded IntelliJ IDEA to a different computer. On one computer it works fine on the other computer it is giving me this current issue.
When i open a new project with a template it automatically shows errors everywhere even though it allows the code to run and shows the output correctly: standard Java library classes like String and System are highlighted in red and the error tooltip says: "cannot resolve symbol".
I have tried "Invalidate caches/Restart", but it didn't help.
Check the JDK configuration Classpath tab in Project Structure | SDKs:
Also check that project and modules use the same JDK.
If it's empty, remove the JDK and add it again. It's not recommended to use JetBrains Runtime as your JDK, download and configure some different standalone JDK instead, 2020.1 version can download JDK for you.
Important notice
The bundled JRE is used for running the IDE itself,
and it's not sufficient for developing Java applications. Before you
start developing in Java, download and install a standalone JDK build.
I tried above, but no luck. I did get it working with File -> Invalidate Caches...
I selected all three checkboxes and then "Invalidate and Restart". That worked for me.
Often this means there is an issue with your java compiler. Normally this issue arises on an initial Intellij install. You can install/update the java compiler to get it working properly.
Go to the editor and type Ctrl + Alt + Shift + A . Then, a little bar pops down and you can select to either install the compiler, or configure it. Both times this happened to me, I just clicked install and once it was done, everything worked. If the install doesn't work, you can just reconfigure your compiler.
Removing the Java SDK and adding it back under File->Project Structure did it for me.
The only thing that worked for me (after hours of trying!) was to use the Android Studio's embedded JDK. "Invalidate caches/Restart" did not solve the issue, even using the same JDK version which was not coming with Android Studio was giving the Cannot resolve symbol 'String' errors. Wonder what's so special with this pre-packaged JDK! Hmmm
For me the solution seems to have been creating a new Run Configuration.
I had tried deleting the SDKs, and re-adding the one I needed but that did not clear the error. But creating a new Run Configuration did the trick.
I had this problem when I uninstalled JDK and re installed it, and when I was making a new project I had the uninstalled JDK file selected, which somehow caused the system to be in red and un run-able.
I'm trying to run eclipse on my Mac OS X. I've been doing some Android programming on Eclipse lately, and today wanted to do some development on Java. However, to my surprise, Eclipse says there's no JRE/JDK installed. I don't know how this is possible, since my android projects have worked very well so far, and even now. I've tried the following items:
Checking java version through the Mac terminal. It says java version "1.8.0_20" is installed. Here's the screenshot.
I've checked the Java version through the Java Control Panel in System Preferences. Again, same thing:
I know that when there's no JRE visible in Eclipse, it can be manually entered through the "add" option under preferences > Java > Installed JREs in Eclipse. But although I can find the Contents folder in this path: /Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/home/contents, when I attempt to manually add this in Eclipse, the Java folder under users/library just doesn't show up. I have no idea why this is happening. Here are some screenshots, just in case:
As you can see, the Java folder just doesn't show up under Library in the above screenshot.
Lastly, I've also tried to hit "Search" in Eclipse (same place as "Add" in one of the screenshots above), but "Search" doesn't find anything at all.
I've gone through existing answers on SO which deal with similar problems. The only thing which I haven't done seems to be about setting a path variable, but they were all in Windows OS, so not sure if it applies in my situation.
I'd really appreciate any help on this.
Update 1: According to what has been pointed out so far, I tried copy-pasting the suggested path. But the error I get is: The home directory does not exist.
Here's the screenshot:
You are trying to find the JRE in a wrong Library directory as Library directory maybe present in more than one place. Just copy paste the jre path in 'jre home' input as
/Library/Java/JavaVirtualMachines/jdk1.8.0_20.jdk/home/contents/Home/jre/
EDIT: To find where is your java installed on Mac, run the following command:
echo $(/usr/libexec/java_home)
it should return something like this:
/Library/Java/JavaVirtualMachines/jdk1.7.0_67.jdk/Contents/Home
append jre to the end of this path to build JRE home path:
/Library/Java/JavaVirtualMachines/jdk1.7.0_67.jdk/Contents/Home/jre
Alright so basically, I'm trying to run Eclipse with JavaFX, but then it gives me this error:
You are not running your eclipse instance with Java7 or Java8. The JavaFX tooling is disabled because of this.Make Java7/8 the default system java or adjust your eclipse.ini to pass -vm pointing to your Java7/8 install.
In case you want to turn off this check open your preferences and go to General > Startup and Shutdown and uncheck 'JavaFX Tooling Java Check'
Now I know it isn't pointing to the right SDK, but I have no idea how to change it, since I'm kind of new to this this stuff. I've already downloaded JDK 7.40 as well. I'm also using Ubuntu on a virtual machine, if that even matters anyway. Can anyone help me, I'd appreciate it.
Pre-requirements:
Install Java™ 8.
Install Kepler SR2 (4.3.2) .
The Kepler is still not supporting Java8. What to do?
Open Eclipse
Help > Install New Software…
Enter the following URL into the ‘Work with’ field:
http://download.eclipse.org/eclipse/updates/4.3-P-builds/
Press ‘Enter’
Select category ‘Eclipse Java 8 Support (for Kepler SR2)’
Click ‘Next’
Click ‘Next’
Accept Licence Agreement
Click ‘Finish’
Now jre8 is correctly located.
Now configure JavaFx
Open Eclipse
Help > Install New Software…
Enter the following URL into the ‘Work with’ field:
http://download.eclipse.org/efxclipse/updates-released/0.9.0/site
Press ‘Enter’
Select category ‘Eclipse Java 8 Support (for Kepler SR2)’
Click ‘Next’
Click ‘Next’
Accept Licence Agreement
Click ‘Finish’
It looks like the default java on your system is not java7. What do you get when opening a shell and execute java -version? Solution is to:
A) make java7 the default java
B) start eclipse with -vm
Apparently, you have installed 32bit Eclipse and 64bit JRE/JDK on a 64bit OS. Please use 64bit Eclipse and the problem will be solved. Please make sure JAVA_HOME And JRE_HOME is present in environment variables.
I had the same issue. I tried re-installing Eclipse, but it wouldn't work. I had to completely remove the project and delete all the project files. After that, I re-started eclipse and created the project again. However, this time I made sure the project path included the Java FX library as shown in the screen shot.
Java Build Path
I did this while I was creating the project and then I was able to create the project without any issues. Give this a try.
I've started encountering some weird exceptions trying to use the GWT designer. I'm on Ubuntu if it matters, GWT 2.4.0, Java 1.6.0_20 x64
When I use the designer, a previously used DisclosurePanel shows up in a pink box indicating. When viewing the details, it indicates a NoClassDefFound error. This makes no sense because in the code editor, the class is visible and compiles without error.
Secondly, I am unable to drop a CellTable instance on the designer. Even with the most basic T = java.lang.Object, the error comes back indicating an IllegalArgumentException : "Unable to find 'columns' in class com.google.gwt.user.client.UI.HTML.
This was working yesterday with the designer, but all of a sudden has entered the crapper. I tried reinstalling the GWT plugins, and even using a new eclipse install with fresh GWT plugins installed, but to no avail. Does anyone know the source of these errors and how to remedy them?
Alright, it seems that the other day I synced up my build machine for the fisrt time and had a different version of java installed on my dev machine. OpenJDK 1.6.0_20 (Iced Tea 1.9), vs Java SE 1.6.0_35.
Since this java was in my /usr/bin which was earlier in my PATH envi var than my 1.6.0_35 build that was at the end of the PATH, it was using hte older 0_20 version. I'm guessing the GWT designer was built with something closer to 1.6.0_35 than 1.6.0_20, and was causing conflicts as implied here.:
Start by checking your Eclipse ".log" file (found in your /.metadata directory). If the error references one of your classes or methods, check that your classpath properly references the class you are trying to use. Also check that your class is properly compiled (no red X's) and that a .class file exists in your projects /bin directory. A mismatch between the JDK used to compile your code and the JVM used to run Eclipse can also manifest itself as a NoClassDefFoundError problem. For example, if you compile your code using JDK 1.5 or 1.6 and then run your Eclipse using a 1.4 or 1.5 JVM, you can have this problem. If the error refers to a custom widget, you should also check that your component does not trigger an exception during its initialization (which can manifest itself as a NoClassDefFoundError). Try refreshing and cleaning your project using the Project > Clean... or Project > Build Project commands. If that does not help, send a test case to support.
I've got a curious problem. After installing java jdk 6u25 I tested the installation by typing java in the command prompt. Everything worked fine , the console displayed the usage options as expected. This was about 3 weeks ago - I recently reinstalled windows 7 on my machine- Now I would like to get started with the play framework and followed a tutorial. I got a new application with play new but couldn't use play run because of this:
play! 1.2.3, http://www.playframework.org
Ctrl+C to stop
Could not execute the java executable, please make sure the JAVA_HOME environment variable is set properly .
The funny thing is that typing java in the console still displays usage options and neither eclipse or netbeans complained about a missing jdk. Nevertheless I checked my environment variables and was surprised to find:
No reference to java at all.
Seriously I got no idea how the console, eclipse and netbeans found my java. As a first countermeasure I once again reinstalled java hoping that the installer might set the path correctly. It didn't. Now I would like your advise: Should I just create the JAVA_HOME variable ? If I do, will further versions of the jdk override the variable to point to the new version or will I have to change the variable manually everytime? What about eclipse and netbeans. I would guess that they have been downloaded with their "own" jdk. If I want to update java on my machine, will it update their versions, too ?
Update:
I set the environment variable manually and restarted the pc. Now everything works fine but I would like to know what symbolic link is. Could you just give me a link in a comment or explain briefly ?
Eclipse and netbeans use a different way of finding your java installation than command line tools likes play, ant, maven, gradle etc.
IDEs may search your registry, guess default locations, or even have the JRE prepackaged with the installation.
Command-line tools usually rely on JAVA_HOME variable. And you have to set that manually.
Should I just create the JAVA_HOME variable ?
There are several tools that use that environment variable, so I'd recommend creating it.
If I do, will further versions of the jdk override the variable to point to the new version or will I have to change the variable manually everytime?
If you install your new Java version into the same folder (or if you create symbolic links), then no.
What about eclipse and netbeans. I would guess that they have been downloaded with their "own" jdk. If I want to update java on my machine, will it update their versions, too ?
That depends on whether the JDK is prebundled and how the configuration is done. I can't speak for Netbeans but in Eclipse, you could add this to your eclipse.ini:
-vm
C:/Java/jre/bin
Note that this is an example path to the bin folder. If you don't add versions there or use symbolic links (see above) then you'd not have to update the path when installing a new version.
It is possible that you have a (older?) java.exe in C:\windows or other common directory.
Make sure that the java you get on the command line is the one you think it is:
java -version