I have some classes in my current project which have the wrong package declaration (they are in the wrong folder for their declared package.)
Unfortunately, fixing the problem by moving the class is not an option. Is there a way I can get eclipse to ignore the error?
You can fiddle with Eclipse's display in the "Errors/Warnings" section of preferences, but Java requires that you have files in the correct folder to match their package, so it won't be able to build
If fixing the problem by moving the class is not an option, is fixing the problem by changing the declared package name an option? If you can't do one of those two things, the code won't compile -- so this wouldn't be an Eclipse problem so much as a Java problem.
Do you have the source folder for Eclipse at the right level? The source folder for Eclipse should be at the level where the package folders start. If there are multiple folders with separate package structures, each one would be it's own source folder.
Related
I want to run my code without creating a package in java eclipse IDE.
But when I do so it is showing error :
Must declare a named package because this compilation unit is associated to the named module 'Games'
You are using the Java Platform Module System (JPMS) which requires not to use the default/unnamed package.
In the default package delete the file module-info.java to not use JPMS and to be able to have code in the default package.
Just right click on the project folder -> New -> Package. Once the package is made, move all your classes into it.
Double click on the error icon at the line number ->move to default package option.
Make sure the classes are (public or protected) to be used in different packages.
In the file in question, right click to get the context menu. Select "Refactor->Move". The resultant dialog will have the (default package) into which the source file may be placed.
Also, be sure to not have a package definition line at the start of the source file.
Please note that the use of the default package is generally discouraged, but there are time I still use it (primarily for printing copyright/version information).
There are also options for turning on hidden/suppressed parent packages, but I think the Refactor approach is the most clean.
The most viable answer to this problem is to remove the module-info.java file located on the Project Explorer tab of Eclipse. This file is created by default. Also, deleting this will not affect your program. Hope this will help.
I cannot run a program in Eclipse Photon (4.8.0). Eclipse keeps telling me that, "Editor does not contain a main type." Even though it clearly does. According to Package Explorer, the java file I'm trying to run is under the src folder, so Eclipse should be able to find it.
So, I think this is because my project doesn't have a default package. Or at least, not one that I can see.
My question is, how can I add a default package to an already existing project in Eclipse?
If you choose to down-vote this, please let me know why. I would like to improve my post if possible.
Here is a screenshot of my Package Explorer.
You cannot use the default package in a project which has a module-info.java.
If you don't need the module system's features, just remove the module-info.java and you can develop as pre java 9.
You can't add a default package but you can add a package by right clicking on the folder and creating a new package and after that adding package "packagename"; on top of the file.
In the Package Explorer panel, right click on your "src" folder, and create a new class. In the window that pops up to ask you for the name of the class (see the picture below), there is a section that has the name of the package. Not providing any name there, would result in the new class to be saved in the "default package".
Note that, default package means that there is no package to hold that class. This is just a way for eclipse to show you that this class is not kept in any specific directory in your computer. It will be stored right inside the "src" folder, next to other packages.
I just started taking this Distributed Systems class, and my teacher says the following on our class website:
Please do NOT use packages! If your configuration of Eclipse uses them
by default, please remove them before writing code!
What the heck is she talking about? I thought eclipse NEEDS to create packages for your project source files to stay organized. How do I remove them?
Packages are not mandatory. If you create a new project in Eclipse, you can directly add your classes to src folder. These files will be under /workspace/project_name/src/ folder. If you add a package, your class files will be placed under /workspace/project_name/src/package_name folder. Your instructor will need to know package names to be able to compile your files and she is probably using a script or something to automatically compile them and that script assumes your files are placed under src folder.
Just remove the first line of your code if exist that says:
package <package-name>;
And if you are creating a new class, then don't give any package name.
I have three .class files that I'm supposed to black-box test. They are under a package named one.two.three. I'm having difficulty accessing them. I started a new java project in eclipse and created a package with the same name. I then proceeded to add the three .class files to bin/one/two/three. If I try using the classes Eclipse can't find them and I get compiler errors. I'm using the appropriate package header. Any help is greatly appreciated, thanks.
assuming bin/ is your output folder in the Eclipse project settings. Simply dropping the class files under bin/one/two/three will not work as eclipse will either delete them (on clean build) or just ignore these extra artifacts. Do as #Ray Tayek says- keep them in a different directory and edit project classpath and add this as class folder. This should work.
another problem. I have already placed my Jython.jar into what my computer recognizes as the Java CLASSPATH. This done, importing anything from Org.Python is not found by the compiler! Do I need to have the Jar in the same folder as the java code as well?
Thanks to anyone who replies :D
---------------------------------------------UPDATE-------------------------------------------
Still not working
within CLASSPATH I have Jython.jar.
within the location of my code and batch-compiler, I have the jar.
and I have typed "import org.python.util.*;" and nothing else are the beginning of my code
and it is still giving me errors :C
Make sure that you spelled the package correctly! In java the convention is to have packages with small letters: org.python
If you are using command line to compile and run your code then you will need to add the folder containing the given Jyhton.jar file.
For more help take a look at: http://docs.oracle.com/javase/1.3/docs/tooldocs/win32/classpath.html
If you are using an IDE:
Eclipse:
Got the Properties/Java Build Path/Libraries. From there you can add external Jars.
Netbeans:
Go to the projects Properties/Libraries/Compile tab and add all the JARs that you want to be included.