I am working on a soucre code which was developed using java 1.4 but now we want to migrate it to java 6. I was able to compile it but there are tons of warnings related to use of java generics wherever we have made use of collections framework. It is possible to remove them by manually make changes to them, but I wanna know if is there any tool which can run on the source code and remove all the warnings by making necessary changes ot the code. Any help will be highly appreciated.
Cheers,
Nitin Ware
Eclipse has an option to try to infer the type arguments for generic types. It's not fool-proof, but it's a start. It's available from the "Refactor" option in the context menu when you right-click inside the class's code.
Open your code with Eclipse, select your Package or Project and in the Refactor menu select "Infer Generic Type Arguments". It will infer the types and correctly change almost all the warnings. Correct the last ones by hand.
Unfortunately sometimes the plugin sometimes crash while trying to do it. I'd also try to do it with IntelliJ IDE. Edit: I've tried with InteliJ and it also failed. Nothing happened after 2 days running. The newer eclipse almost worked, just crashed in 2 files. I'm using it in a very old project with non-standard paths. Maybe you'll have better luck.
You could suppress warnings as a compiler option
-nowarn or -Xlint:none
see http://java.sun.com/javase/6/docs/technotes/tools/solaris/javac.html#options
In eclipse you can set the "Target" JVM to 1.4, that should fix your problem in the editor. I think you can also specify a target option to javac, but I'm not sure about that.
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
I am a beginner developer trying to create my first project using Jhipster. I am trying to set up everything to start coding in the most accurate environment in order to avoid further problems or warning in the future.
I have imported the new project to the Eclipse IDE following the instructions in jHipster web, but as you can see in the picture, some warnings appear:
Is there something important that I have to worry about? If yes, how can I solve it?
I can solve the first one, but I am not sure if I solve it in the right way. I did not find any solution related to the other ones.
Is there something important that I have to worry about? If yes, how can I solve it?
Warnings are not high priority problems, they will not break your application. That said fixing them is never a bad idea, I personally like to keep my projects clean.
Most of the Java problems you have are for unused imports or variables, remove them from your code and the warnings will disappear. You can double click on each warning and eclipse will take you right to the line of code.
For the serialVersionUID problems you can just click on the yellow light bulb left of the line number and then click Add default serial version ID.
The first two problems you say you can fix them, good. They are telling you there is a mismatch between the expected Java version and the one used. One way to fix them is to install the 1.8 JDK (get it from here) and set it as your default JRE (Windows > Preferences > Java > Installed JREs).
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
This error is just bizarre, my code compiles fine, I can see there are no problems with it, yet this error has just popped up. I have tried re-starting NetBeans and there is no additional exception information.
What can cause this?
If it is Netbeans, try to uncheck "Compile on save" setting in the project properties (Build -> Compiling). This is the only thing which helped me in a similar situation.
I guess you are using an IDE (like Netbeans) which allows you to run the code even if certain classes are not compilable. During the application's runtime, if you access this class it would lead to this exception.
It's caused by NetBeans retaining some of the old source and/or compiled code in its cache and not noticing that e.g. some of the code's dependencies (i.e. referenced packages) have changed, and that a proper refresh/recompile of the file would be in order.
The solution is to force that refresh by either:
a) locating & editing the offending source file to force its recompilation (e.g. add a dummy line, save, remove it, save again),
b) doing a clean build (sometimes will work, sometimes won't),
c) disabling "Compile on save" (not recommended, since it can make using the IDE a royal PITA), or
d) simply remove NetBeans cache by hand, forcing the recompilation.
As to how to remove the cache:
If you're using an old version of NetBeans:
delete everything related to your project in .netbeans/6.9/var/cache/index/ (replace 6.9 with your version).
If you're using a newer one:
delete everything related to your project in AppData/Local/NetBeans/Cache/8.1/index/ (replace 8.1 with your version).
The paths may vary a little e.g. on different platforms, but the idea is still the same.
I also got the same error and I did clean build and it worked.
Add selenium-server-standalone-3.4.0.jar. It works to me.
Download Link
Recheck the package declarations in all your classes!
This behaviour has been observed in NetBeans, when the package declaration in one of the classes of the package refers to a non-existent or wrong package. NetBeans normally detects and highlights this error but has been known to fail and misleadingly report the package as free of errors when this is not the case.
I had the same issue with one of my netbeans project.
Check whether you have correctly put the package name on all the classes. I got the same error message because i forgot to put the package name of a certain class (which was copied from another project).
Disable Deploy on Save in the Project's Properties/Run screen. That's what worked for me finally. Why the hell NetBeans screws this up is beyond me.
Note: I was able to compile the file it was complaining about using right-click in NetBeans. Apparently it wasn't really compiling it when I used Build & Compile since that gave no errors at all. But then after that, the errors just moved to another java class file. I couldn't compile then since it was grayed out. I also tried deleting the build and dist directories in my NetBeans project files but that didn't help either.
Organize your code as a maven module.
Once done run the command from terminal
$mvn installl
to check if your code builds fine.
Finally import the project in netbeans or eclipse as maven project.
change the package of classes, your files are probably in the wrong package, happened to me when I copied the code from a friend, it was the default package and mine was another, hence the netbeans could not compile because of it.
I had this problem with NetBeans 8.0.1. Messages about problem in project deleted class. Deleting the ~/.netbeans didn't work. Also I looked for ANY reference to the deleted class in ALL my projects, nothing found. I deleted the build classes, everything. Then, when I started Netbeans again, compile and magically appears the message in Run and into the mother compiled class. I tried the uncheck "Compile on save" Dime solution, and works, but it's not practical.
Finally, my solution was edit and force recompile of the mother class. This way the new .class doesn't contains the message and Run works OK.
Just check the packaging, the simplest answer I can provide is that your package has been mislabeled (within a class).
Also, you may have some weird characters. Try white-flushing the code in a Notepad (or Gedit) and then pasting it into a newly created class with your IDE.
If you are using Netbeans, try to hit the Clean and Build button, let it do the thing and try again. Worked for me!
I had the same problem. My error was the packaging. So I would suggest you first check the package name and if the class is in the correct package.
Implementing my own functional interfaces resolved this for me (so instead of using java.util.function.* just create your own single-method interface with the parameters and return-type you want).
In Netbeans, I used some scala code (jar) written by someone else and included it into a java project project along with Scala-library.jar. It worked nicely without hiccups.
Now when I try to do the same using eclipse, I get the following build error
Internal compiler error: java.lang.ClassCastException:
org.eclipse.jdt.internal.compiler.lookup.BaseTypeBinding cannot be cast to
org.eclipse.jdt.internal.compiler.lookup.ReferenceBinding at
org.eclipse.jdt.internal.compiler.lookup.BinaryTypeBinding.initializeTypeVariable(BinaryTypeBinding.java:944) DemoApp.java /demo/ line 0 Java Problem
On Googling, I found that others have had this problem but not seen any fixes.
If any of you have seen this error and figured how to fix it, please share it here.
Let me know if any other information is needed. Unfortunately, I do not have the source of the Scala code that I used, just the jar. If you need the code of DemoApp.java, I can paste it here, but that is not very useful: it just references an object in the Scala code.
Details: scala-2.8.0.r22602-b20100720020114
Thanks.
One of the problems of Scala is its lack of binary compatibility between different versions.
Either use the same library version with which the original Jar was compiled, or recompile the Jar (if that's an option).
Do you have JDT Weaving enabled? Go to Preferences -> JDT Weaving to find out. If it is disabled, then you may have inexplicable errors in your IDE.
Ok. I finally found the solution!
Thanks to this SO question
The problem seems to be Scala 2.8 compiler (apparantly). This issue is not there in 2.9.
One of the fixes suggested was to use Scala 2.9, but that is not always possible. So here is the right solution.
The problem lies in the List type of Scala. I found that I was returning (exposing) a List in the Scala code somewhere, which was causing the problem with Java in Eclpise.
To fix the problem, do not return List. Return Array or some Java type.