In Visual Studio land, I used to be able to define a structure in an XSD file and add a special attribute to it which would cause it to be dynamically compiled and available to use with intellisense in the other C# files in the application. I am not sure exactly what the term for this is, perhaps "dynamic code generation."
I am trying to accomplish the same in Java using Eclipse IDE. Basically what I am looking for is a tool that will allow me to specify some template and generate Java code from it in a "hot folder" that will allow me code complete in the other static Java files.
Does anyone know of a solution for this? I know it is possible in Visual Studio, but I can't seem to find anything for Eclipse.
Ok, here is exactly what I want to do.
Step 1. I create a folder called templates
Step 2. I create a file called HelloWord.ibes
Step 3. Code it automatically generated in my src folder HelloWorld.java
I want to be able to do this in eclipse easily.
You may create an ant build file that does the source generation for you. Then you are free to use any code generator you like. Ant support is part of the eclipse IDE. If you prefer maven, there's a nice eclipse pluging available (that's what I actually use for source code generation based on jaxb, javacc and xdoclet...).
Technically spoken, you just add another eclipse builder which is invoked anytime eclipse detects a change in your code base.
If you already have a code generator in mind, just 'ask' the internet if there's a plugin available.
Edit
On how to install a builder: This is done automatically. For maven, you just install the maven plugin (m2eclipse) and enable maven dependencies for a project. Then if you look at the projects properties pages (Builder section), you find a second entry in the list of builders.
It's similiar with ant, even easier, because ant is already integrated. "enable" ant for a project and the builder is added to the list of builders for the project. You can deselect it at any time if it kills performance or switch of automatic building (I don't know by heart how to enable ant builds for a project, but I remember that the eclipse help had sufficiant informations).
All about ant can be found here: Apache Ant
Creating a new builder is difficult, as it has to be coded in java and added to eclipse as a plugin. I bet you don't want to follow that track ;)
I'm not sure whether you have seen the code template option?
Preferences.Java, Code Style then Code Templates
How
to add code templates
Useful
code templates
Related
I am a java beginner, the first java IDE I downloaded was Visual Studio Code, it was very easy to use and everything is auto configured. But it kind overheats my laptop all the time, so I want to try IDEA, so far it's a very good experience, except when I open a java file and tried to run it in IDEA, it always pops out this run configuration window and I don't understand how to configure it. In visual Studio Code I can open any java file any time and run without any issues, but now I have to go through creating projects every time. Is there any solution for this?
From how the file icon looks:
your file is not recognized as the part of the sources of your project. Check the project settings to ensure that source directories are correctly set.
I'd also recommend you to look up and follow the conventions for the directory structure of java projects.
Once you've fixed the problem with sources, you'll see "run" icon next to your class, main method, or when you're right clicking the file.
Command-line
To run a single file, there is no need for an IDE.
In Java 11 and later, the java tool at the command-line can both compile and execute a single-file Java class. See JEP 330: Launch Single-File Source-Code Programs.
If your class named HelloWorld were in a file named HelloWorld.java, on a console type:
java HelloWorld.java
To be clear: The java command-line tool really only executes Java apps, while the javac command-line tool compiles Java source code. As a convenience, the java tool was enhanced to effectively call javac on your behalf for a single-file.
JShell
If you just want to run a few lines of Java, try JShell, the REPL tool bundled with Java 9 and later.
See:
Java Shell User’s Guide by Oracle
JEP 222: jshell: The Java Shell (Read-Eval-Print Loop)
Search to learn more and find tutorials.
BlueJ
Using an IDE such as IntelliJ, NetBeans, or Eclipse can be a daunting task for the new student of Java. Those IDEs are heavy-duty tools designed for professional programmers.
I recommend using an IDE designed for beginners. BlueJ comes to mind, designed specifically for educational purposes. BlueJ makes getting started with Java easier.
If you insist on using IntelliJ, read on.
If using IntelliJ, define a project
IntelliJ is not designed to work with single files. IntelliJ expects you to work within a project.
I strongly recommend learning the basics of Maven to create and drive your new project. By defining your project in Maven, the configuration is independent of any one IDE. You can move your project between major IDEs such as IntelliJ, NetBeans, and Eclipse.
Maven is also very useful for downloading needed libraries ("dependencies") that you may want to leverage in your work. And Maven is good at packaging your Java app as a JAR (or WAR or EAR).
In IntelliJ, choose "New Project". In the New Project window, click the Maven item on left. Check the Create from archetype box. Scroll the list to find item for org.apache.maven.archetypes:maven-archetype-quickstart. Under that, choose the "RELEASE" item. Click Next button.
In Name field, enter something like MyFirstProject. Click Next button.
On the Maven settings page, just click Finish.
Wait a moment for IntelliJ to download some stuff and configure your project. Eventually you should see a BUILD SUCCESS message in the Run pane.
You will also see a pom.xml file displayed. The POM contains your settings for Maven to run your project, in XML format.
Change the <maven.compiler.source> and <maven.compiler.target> elements to the version of Java you are using. The current version is Java 17.
After editing the pom.xml, look for a little floating windoid with a tiny Maven icon. Click the icon to have Maven process your changed POM. Wait a moment.
In the Project pane, navigate to the App file. There you see code to print “Hello World!”. Let's run that code now. Click the green triangle button on the left, in the gutter, next to the main method line. A pop-up menu appears offering a Run item. Choose that item to run the app immediately.
Down in the Run pane, you should see the results, the Hello World! text.
At this point you can add your single file to the org.example package seen in the Project pane.
By the way, you can change that package name by context-clicking and choosing Refactor > Rename….
Later, learn to use the Run/debug configurations feature of IntelliJ.
Know that you need not create a new project for each time you want to do a little experiment. Create one project for such experiments. Keep adding new .java class files for each experiment. Delete old class files you no longer need.
Eventually, I suggest updating the versions of various items in your POM. The QuickStart archetype is not configured for the latest versions (for reasons I cannot fathom).
And when you learn about unit testing, replace JUnit 4 in the POM with JUnit Jupiter (Aggregator) to use JUnit 5. One of the benefits of using Maven is that you can easily switch out dependencies such as going from JUnit 4 to JUnit 5.
The IDE needs to know what's called the entry point of the program, i.e. where to start running your code. That's what the "Edit Configuration" window is wanting you to do.
If your file "Lab3.java" is in a package, make sure to fully specify that in the field you have in red. Otherwise without knowing how your project is structured (as the other answer alludes to), it's difficult to pinpoint what we're missing here.
When you create your IntelliJ project, add a directory /src right at the root of your project. Right click on that folder and tell IntelliJ that you wish to mark it as a source root. The directory should turn blue in color.
Put your packages under /src. IntelliJ will know that those are Java files.
When you want to run a class with a main method, choose Run->Edit Configurations. Tell IntelliJ that you want to add an Application. It should prompt you with the classes that have main methods in them. You'll have no trouble running them.
Use Maven or Graddle. Make sure the project is configured with the build tool enabled and integrated, it will do basic things automatically. If you are not sure, please create a new project and add your files in. Steps:
Open the IDE
New Project
Choose from the left side bar "Maven" or "Graddle"
Give it a name and the location in your machine.
Click Finish
Now you have the project ready. You need the appropriate method to run in java. A main class. In IntelliJ you can just type "main" and the auto-complete will add it for you, make sure you inside the curly brackets of the class {}. More info about the main class. You seem to have this nailed down.
Lastly make sure you have a JDK installed in the IDE. I am pretty sure this is your issue here, make sure to use one of the option IntelliJ provides. A full guide from the developers is here and should satisfy your needs. I would suggest OpenJDK for a beginner, because that served me well at the beginning, at the end of the day its your choice.
I have installed an Eclipse plugin called PMD and I want to use only one of its feature (extracting Abstract Syntax Tree). The main problem is, instead of right clicking on each Java source code and then clicking on the AST feature, I want to fully automatize it without clicking on anything.
Therefore, the question is is there a way or method to call that plugin's feature from the source code that I have written.
I have tried to import PMD's maven project, however I have encountered some errors and there are many features that I won't be using (supporting other languages etc.). Thereby, I'm trying to find a more lightweighted approach. PMD is a quite big project to integrate it into my own project.
Thanks in advance.
Apparently, PMD Plugin has its source code open. Therefore, when the relevant classes and methods are converted into a standard Java desktop application (rather than Plugin), it is possible to create AST files without and UI interactions.
The conversion part is quite simple and easy. Since PMD Plugin requires UI, it uses classes such as IFile, IProject etc. Thereby, these classes could be changed equivalent classes such as; File, Project etc.
After giving the path of the project and by adding a simple code that recursively traverses its sub-directories will help you find all of the Java source files. Then by sending each of the Java source files into the AST generator method will do all the trick.
I have an eclipse Java project and want to get information like project source dir, classpaths, etc. My current implementation parses the .project file. But as I didn't find any official documentation describing the structure of the .project file, I have some concerns for the robustness of this approach.
A more convenient and robust way would be to use JDT (headlessly) to load the project and get the relevant information from the IJavaProject object.
Although the developer guide of JDT says
JDT Core packages give you access to the Java model objects and headless Java IDE infrastructure.
all the examples I can find opening an existing Java project get the IJavaProject object from projects within a workspace or use an IProject object. But I couldn't find the way to add a project to the workspace or to construct a IProject/IJavaProject from a path to .project file.
Could anyone please help?
Yes, and can all be done through clear and stable API. org.eclipse.jdt.core is a plug-in, just like org.eclipse.core.resources (which is where you would get an IWorkspace instance), and they both expect to be running within an Eclipse runtime, which can be headless if that's how you write your Eclipse Application. JDT uses the .classpath file to record where sources, libraries, and build output are, and what abstracted references to libraries to use, while the .project file is what records what kind of project it is in general--Java, PHP, Web, some combination of those or others--and a little more information about what builders to execute.
So make yourself a headless Eclipse Application, or package your end-goal functionality inside of one.
https://wiki.eclipse.org/FAQ_What_is_an_Eclipse_application%3F
https://wiki.eclipse.org/FAQ_What_are_extensions_and_extension_points%3F
http://help.eclipse.org/mars/topic/org.eclipse.platform.doc.isv/reference/extension-points/org_eclipse_core_runtime_applications.html?cp=2_1_1_27
http://help.eclipse.org/mars/topic/org.eclipse.platform.doc.isv/reference/api/org/eclipse/core/resources/ResourcesPlugin.html#getWorkspace--
http://help.eclipse.org/mars/topic/org.eclipse.jdt.doc.isv/reference/api/org/eclipse/jdt/core/JavaCore.html#getJavaCore--
http://help.eclipse.org/mars/topic/org.eclipse.jdt.doc.isv/reference/api/org/eclipse/jdt/core/IJavaProject.html#getResolvedClasspath-boolean-
See http://www.ant4eclipse.org/ for a project which allows you to work inside Eclipse projects.
I used it for a bit some years back, and found that this is too brittle for long term usage and build scripts. I would recommend against relying on internal Eclipse things. They break! Typically when mixing releases.
Instead I would suggest you move to Maven. This is a bit more work, but allows you to use the whole maven infrastructure and API's to do things. What you want to achieve here, may be possible already using a Maven plugin.
I'm trying to learn project automation and I'm using the book Pragmatic Project Automation as a guide. It's examples are in Java so I find it easier to follow it along in Java. I don't have any experience using Java or any of its IDEs. However, I've learned some C# using Visual Studio (although I'm still a beginner).
I'm having trouble understanding some parts of setting up a Java project. I'm using Netbeans IDE 7.0 on Windows 7. With Visual Studio, I have a solution with projects underneath. With Netbeans, I appear to just have a project with directories determining the rest of the structure (and the IDE to some degree)? The equivalent to Add Reference appears to be adding a source to the Classpath. There also seems to be a degree of separation between the compiler and the IDE. I'm currently in a situation where I can compile my project just fine while the IDE tells me I still have errors (and I assume this is because I have the project set up incorrectly).
I'm basically looking for analogies that will help me better understand Java project structure.
Lots of similarities between the two languages and IDEs. I spent many years in both. For starters the equivalent to 'add reference' in VS is adding a library or jar in netbeans. In respect to a reference - a jar is pretty much the same thing as a module or .dll in VS. A jar is a compiled reference. To add a reference just go to the project menu and then properties then to the libraries menu from there you can add either pre-assembled netbeans libraries, which are collections of .jar's, or a single .jar, or even a project. Once you add a reference you can import them into your class just like you would in C#.
Netbeans doesn't really have a 'solution' as VS does. You deal with individual projects. It does however have the capability to add a project as a reference so you don't have to continually re-build the references when you change something between multiple projects. It also has project groups to group similar projects.
Lastly Apache ANT is responsible for tying everything together in the background. Netbeans creates a build.xml and build-impl.xml file in the background to tell ANT how to assemble the project into a .jar.
There are my other things to cover but I thing this answers most of your questions. Does this help?
I can't speak for NetBeans, as I use Eclipse, but you are on the right track with classpath being roughly equivalent to references in the Visual Studio world. Libraries (usually .jar files) are placed on the classpath and must be there both at compile time and runtime (you specify the classpath to the compiler at compile time, and to the JVM at runtime). The classpath can contain many different entries, and they can be anywhere in the project structure (or outside of it entirely).
Java itself doesn't impose many restrictions on your project structure, although various IDEs and build tools do. The one thing that is a universal restriction in all Java environments is that source files (and class files) are placed in a directory named after the package name. So if your package name is com.test.something, then your source files will be in SRC_DIR/com/test/something, and your class files in OUT_DIR/com/test/something (note: SRC_DIR and OUT_DIR are not special variables; each IDE will have a different way to specify those directories).
Java libraires tend to heavily build-on one-another, so at some point, you'll find that the classpath entries are too many to manage manually. Before you get there, you'll want to take a look at Apache Maven or Apache Ivy which are dependency management tools. You'll need to understand how they work (either one, not both) and how to integrate them with your IDE. If you use Eclipse and Maven, m2eclipse offers fairly complete integration between the IDE and the dependency management tool.
With Netbeans, I appear to just have a
project with directories determining
the rest of the structure (and the IDE
to some degree)?
Visual Studio dictates a particular project layout and since the compiler is so tightly integrated into the IDE there's no real concept of a build script. In contrast, Java has no such structure (although certain 'best practices' have emerged such as having a 'src' directory for source files, 'lib' for libraries, 'test' for test source, etc.) and a build script is usually required to tell the compiler were to find source files and libraries, what artefacts to produce and a miscellany of other chores (running tests, deployment, creating code metrics and so forth).
In simple cases, the IDE will take care of this for you (if you follow the convention for that particular IDE) but ultimately you will probably want to take a look at a build tool to understand what's going on behind the scenes. Apache Ant and Apache Maven are both prominent offerings. Ant is very flexible whereas Maven attempts to dictate a common layout. I suggest you investigate both and see which suits.
There also seems to be a degree of
separation between the compiler and
the IDE. I'm currently in a situation
where I can compile my project just
fine while the IDE tells me I still
have errors
If your code compiles, it is correct. The IDE is simply acting in an advisory capacity (and will highlight issues beyond compiler errors, such as warning you of potential code mistakes or bad practice).
and I assume this is because I have
the project set up incorrectly
This is a possibility although, as stated above, there are many other explanations.
I have looked for an answer for this nearly every where that I can think of, but there doesn't seem to be any way to actually SEE what Eclipse "runs" to compile the projects (as it does need the JDK installed and visible to actually build). I ask because I imported a few jars into my project, and even though I've looked through all the javac documentation, I can't seem to figure out how to mimic it quite like Eclipse does. I really, really need to be able to compile on the command line in this case - Eclipse or any other IDE just isn't what is needed.
I started to look through the Eclipse source, and although this sounds lazy, I just became overwhelmed and figured I would ask here first, hoping someone else had the same question at one point.
Eclipse JDT does not require the JDK and does not use javac - it uses it's own compiler.
You can see the classpath by reading your project .classpath file. The various builders that are used to perform build operations (Java, or whatever the project builds) are listed in the .project file. (These are also listed in the project settings.)
It is possible to invoke Eclipse to build your project in headless mode, or write Ant scripts that can be executed both with the JDK and within Eclipse, or install Maven support for internal and external building. It is also possible to configure the project builders to rely only on external tools.
Look at these two articles.
http://www.eclipse.org/articles/Article-Builders/builders.html
http://www.eclipsepluginsite.com/builders-natures-markers.html
Look at your .classpath file and start building an ANT build.xml. You need to do this to be able to have consistent builds on a build machine anyways. It is unlikely that a build server would have eclipse installed on it anyways.
Maven is also another tool that is used for builds. In our shop we use Ant.
Have a look at ant4eclipse - this project allows for generating the appropriate ant data structures for invoking <javac> from the .classpath files and a projectSet.psf file.
By using this we can use Eclipse "natively" and bend ant to conform to Eclipse. The usual approach is the other way around.