I was just looking at my java project in eclipse, compiled it, and after closing program all projects in my solution show billions of errors.
Example:
The import java.awt cannot be resolved
When i try to compile it show error:
A JNI error has occured, please check your installation and try again.
Any clues how to fix it? I had many problems with java in the past and i couldn't fin any fixes, almost like it was designed to fail. This language vexes me, but sometimes you just have to use it.
Edit
I also get this error while attempting to open it in IntelliJ (just downloaded it):
JDK jre.1.8.0_241 is missing
Edit
Its just Java being Java (aka not working, as usual). You have to create new project and just copy everything to it, it will work.
Related
Just starting working on an existing project at work and wanted to use Visual Studio Code as my IDE (I have used it for a recent Rails project and loved it, so wanted to try with Java).
However, whenever I try to open one of the projects I receive a ton of different errors including:
When importing java.io, java.util, or anything similar, the error:
"The import of java.io (or java.util) cannot be resolved"
Existing classes have an error:
"The implicit super constructor is undefined for default constructor. Must define explicit constructor"
Other random "cannot resolve to a type" errors.
All of these seem to stem from some sort of setting error I have with VS Code but can seem to find what it is. I have already uninstalled and reinstalled the RedHat plug-in that enables the Java language for VS Code.
I have tried setting the java_home setting in the extension to the direct location of the install but that didn't work. Tried uninstalling and reinstalling java and that also didn't work.
My operating specs are as follows:
OS: macOS Sierra
VS Code version 1.15.1
JDK version 1.8.0.144
Any idea on what may be causing this? Do you think it may be an error in how I have VS Code set up or if it's an error (or rather incompatibility) with how the existing project is set up?
I ran into a similar issue. The solution was to remove everything from VS Code's workspace storage directory, which was located at $HOME/Library/Application Support/Code/User/workspaceStorage/.
I found this solution here: https://github.com/redhat-developer/vscode-java/wiki/Troubleshooting#clean-the-workspace-directory
Update: This can now be done from within VS Code as of Language Support for Java(TM) by Red Hat Version 0.33.0. Open the command palette and type "java clean" (see official description in link).
As already mentioned previously, you require to clean the project, but that is a bit difficult thing because every folder is a Guid, and you do not know which one to clear, thus requiring you to delete everything. Starting with 0.33.0 version of the plugin you can automatically do that from within the IDE as well, use CTRL + Shift + P and type, java clean, and IDE will show you the suggestion tip for, Java: Clean the Java language server workspace. Upon selection, agree and restart the IDE. It will clean the language server workspace for you.
Another approach can be, the Maven tools within the IDE. If you have this plugin installed, you can use the side bar and utilize the Maven project helper options to perform actions like, clean, install, and package etc. For example, here is the project I am having and the options this shows,
That can be used, graphically, to manage your Maven-based projects. Also, this would work with the Java Extension Pack, not sure yet as to how it would behave with other extensions.
For me: CMD + Shift + P
Then type "Java: Clean Java language Server Workspace"
Note: This will reload/restart vscode as well.
Update:
This appears to not fix it anymore for me. In my case I am using a gradle project, and needed to set the rootProject.name in the settings.gradle to be the same as the folder name that the project is in.
I faced this issue after creating a whole Java project in one computer and then trying to run it on another computer.
After doing everything said in the other answers, what really made VS Code compile was to open each single project java file in VS Code and save it (a simple Ctrl + S). Maybe there is a simpler way of doing it, but that is what worked for me and I hope this helps anyone stuck in this issue.
Press ctrl+shift+p
then search 'java clean' and click 'java: clean java language server workspace' then click restart IDE.
I found another simple trick at least to get rid of "cannot be resolved to a type" errors which were coming from older workspaces and wrong project files I guess?. I just ran an empty main(), with the body commented out, while still keeping my local package / import commands at the start - no errors. After commenting in again, the project compiled without errors. Perhaps this refreshing effect might also help in this context?
I had to clean this folder to get it working on Windows
%APPDATA%\code\Local Storage
Just starting working on an existing project at work and wanted to use Visual Studio Code as my IDE (I have used it for a recent Rails project and loved it, so wanted to try with Java).
However, whenever I try to open one of the projects I receive a ton of different errors including:
When importing java.io, java.util, or anything similar, the error:
"The import of java.io (or java.util) cannot be resolved"
Existing classes have an error:
"The implicit super constructor is undefined for default constructor. Must define explicit constructor"
Other random "cannot resolve to a type" errors.
All of these seem to stem from some sort of setting error I have with VS Code but can seem to find what it is. I have already uninstalled and reinstalled the RedHat plug-in that enables the Java language for VS Code.
I have tried setting the java_home setting in the extension to the direct location of the install but that didn't work. Tried uninstalling and reinstalling java and that also didn't work.
My operating specs are as follows:
OS: macOS Sierra
VS Code version 1.15.1
JDK version 1.8.0.144
Any idea on what may be causing this? Do you think it may be an error in how I have VS Code set up or if it's an error (or rather incompatibility) with how the existing project is set up?
I ran into a similar issue. The solution was to remove everything from VS Code's workspace storage directory, which was located at $HOME/Library/Application Support/Code/User/workspaceStorage/.
I found this solution here: https://github.com/redhat-developer/vscode-java/wiki/Troubleshooting#clean-the-workspace-directory
Update: This can now be done from within VS Code as of Language Support for Java(TM) by Red Hat Version 0.33.0. Open the command palette and type "java clean" (see official description in link).
As already mentioned previously, you require to clean the project, but that is a bit difficult thing because every folder is a Guid, and you do not know which one to clear, thus requiring you to delete everything. Starting with 0.33.0 version of the plugin you can automatically do that from within the IDE as well, use CTRL + Shift + P and type, java clean, and IDE will show you the suggestion tip for, Java: Clean the Java language server workspace. Upon selection, agree and restart the IDE. It will clean the language server workspace for you.
Another approach can be, the Maven tools within the IDE. If you have this plugin installed, you can use the side bar and utilize the Maven project helper options to perform actions like, clean, install, and package etc. For example, here is the project I am having and the options this shows,
That can be used, graphically, to manage your Maven-based projects. Also, this would work with the Java Extension Pack, not sure yet as to how it would behave with other extensions.
For me: CMD + Shift + P
Then type "Java: Clean Java language Server Workspace"
Note: This will reload/restart vscode as well.
Update:
This appears to not fix it anymore for me. In my case I am using a gradle project, and needed to set the rootProject.name in the settings.gradle to be the same as the folder name that the project is in.
I faced this issue after creating a whole Java project in one computer and then trying to run it on another computer.
After doing everything said in the other answers, what really made VS Code compile was to open each single project java file in VS Code and save it (a simple Ctrl + S). Maybe there is a simpler way of doing it, but that is what worked for me and I hope this helps anyone stuck in this issue.
Press ctrl+shift+p
then search 'java clean' and click 'java: clean java language server workspace' then click restart IDE.
I found another simple trick at least to get rid of "cannot be resolved to a type" errors which were coming from older workspaces and wrong project files I guess?. I just ran an empty main(), with the body commented out, while still keeping my local package / import commands at the start - no errors. After commenting in again, the project compiled without errors. Perhaps this refreshing effect might also help in this context?
I had to clean this folder to get it working on Windows
%APPDATA%\code\Local Storage
Recently I have been working on coding Minecraft mods. Yesterday i updated to a 64 bit version of Java, and I began to receive an error that said something of this nature: "Java returned error = 13". I looked around, and discovered that my Eclipse was not 64 bit, so I went to Eclipse, and downloaded the latest 64 bit version. I then replaced my normal eclipse folder with the new one, and it launched fine. However, when I open Eclipse, (I open the exact same workspace as I did before all of this happened), I don't see anything in the Package Explorer view. Nothing at all. Typically it says MDK Example or something like that, and within that are all of my packages, etc.
Here is my question: How can I make it to where I see all of my files in the package explorer like they used to? I am using the same Workspace...
Just a warning: I code a lot, and I believe that now I'm quite skilled at it, however I am not good with computers themselves (hence why I find myself in this predicament). If I need to completely start over, I can, and I can copy over my code. It would be a nuisance but if that is all that is left to do I will do so.
Thank you for reading! Please help if you can :)
I remember encountering a similar problem after having switched the location of my workspace.
Try the following: Choose a different location for your workspace and then choose File>Import>General>"Existing Projects into Workspace".
I'm writing an Android application and there's some Java code in it that's somewhat sophisticated and therefore hard to verify the correctness of in the Android environment. I would like to run this code in a desktop environment where I have more tools with which to examine the output of this code while still using it in my Android application.
My attempted solution is to have three different projects in Eclipse. My Android project and two plain (non-Android) Java projects. One Java project has the sophisticated code that I want to use in Android and the other is a test program that verifies the correctness of the former project. The latter project has already been useful in debugging the former.
However, so far, my attempts to use the Java project in my Android project appears to work in the IDE but when I actually run the Android application, the NoClassDefFoundError exception is thrown whenever I try to access any of the classes. Obviously, that code is not being recompiled into the .dex file but why not?
I could go into detail about what I've done so far but I can't help but think that what I'm doing is a pretty standard and simple thing and there's a plain way of doing it, even though I can't find anyone doing quite what I'm trying. Can someone describe to me how this is done?
Luckily, I found the answer to my own question and I thought I'd share it here to help others in the same situation. It turned out to be very simple...
What I was already doing would have normally worked, which should have been a big clue to me since I have actually done this before, successfully. All you have to do is, under your Android project's Properties > Java Build Path > Projects, add the plain Java project to your "Required projects on the build path" and then under Properties > Java Build Path > Order and Export, check the checkbox of that same project in the "Build class path order and exported entries" list and everything should just work.
From within Eclipse, there's nothing else you need to do to get this setup to work. It's only when you're compiling from the command line that you need to build Java Jars and import them as libraries but I'm not doing that (yet).
Finally, this wasn't working for me because I just happened to be compiling my plain Java project under JDK 1.7 compliance, while my Android project was compiled under JDK 1.6. This is verified by the output on the Console pane, reporting "Dx bad class file magic (cafebabe) or version." This error message goes away when both projects are compiled under the same compliance level and, not coincidentally, the Android program runs properly.
Thank you to everyone who tried to help and I hope this answer is helpful to someone out there!
Would it not work if you made your other plain java project into an Android project and use it to monitor the output on the device?
I recently became interested in Minecraft modding, so I downloaded MCP (Minecraft Coder Pack) and Eclipse. After running decompile.bat, I opened Eclipse using the workspace provided by MCP. At first I was given a list of errors related to missing libraries, but I easily fixed that by fixing their paths. Then I continued following the video tutorial I was using and pressed "Run" and selected "Client" as the project to run. Eclipse gave me the following error:
Must specify a URI scheme:MCP_LOC/jars
I have been Googling this for the past 20 minutes with no success. What is wrong, and how do I fix it?
I can probably still program mods for Minecraft and even recompile them with MCP, but it will be difficult to test them. Does anyone know what's wrong?
NEVER START IN ECLIPSE
Try This vid for 1.7.3
Its a nice little series about minecraft modding.