I am looking for good and practical resources that will help me use the Ant APIs effectively. The project website just gives the documentation of the API which is not useful at all. Very few websites seem to give very brief tutorials on the subject.
Is there some resource I am missing out on? How can I use the Ant APIs for simple tasks, without spending hours browsing through them and looking at source code?
Thanks.
(Answers to previously asked questions not helpful - How can i use Apache ANT Programmatically )
As it turns out, the lack of good resources on using the Ant API, is known and intended.
The bottom paragraph of this article from the Ant says -
The question you are probably asking yourself at this point is: How would I know which classes and methods have to be called in order to set up a dummy Project and Target? The answer is: you don't. Ultimately, you have to be willing to get your feet wet and read the source code. The above example is merely designed to whet your appetite and get you started. Go for it!
So this seems to be the only way to make best use of the API.
..Java program to programmatically build source files
If compiling/Jarring is all you need and you can run it in an SDK (as opposed to a plain JRE), look to the JavaCompiler class for compilation. Then use the Jar related classes to build the Jars.
All J2SE. Ant not included, Ant not required.
There is no better manual to understand ANT than : http://ant.apache.org/manual/index.html
I am not sure if you've gone through this link that explains in detail about creating a task. A word of caution, If you're new to ANT, there is no easy way to jump on this tutorial. Better to learn the basics before you come here. Refer above link for a good starting point.
Related
I want to get started with Java! I have a bit of experience with C/C++ and Python development. For this i'm mainly using Emacs (a text editor) and the commandline, thus not using a heavier weight IDE for those kind of things.
I don't want to adapt my workflow to suit an IDE, but I don't know the Workflow (write, build, test) in Java so I thought about asking here. Searching the Web didn't give me good results.
Can someone give me the the basic workflow when developing Java with my requirements? I use Linux for all my programming.
Are my requirements/wishes even practical or should i consider using something like IDEA or Eclipse?
Can someone point me to documentation or blog posts about this topic or documents, that give a quick overview and/or examples on how to get started with Java (something for programmers with a little experience in other languages)?
For this I'm mainly using Emacs (a text editor) and the commandline,
thus not using a heavier weight IDE for those kind of things.
An IDE has many advantages over a text editor, mainly when navigating, debugging and refactoring code, but it is not required. Actually, working without an IDE is useful to understand the underlying technologies. My advice would be: Start without an IDE, and when everything works, try out some IDEs to see how they help you.
Can someone give me the the basic workflow when developing Java with
my requirements?
The basic workflow is (for any compiled language):
write source code
build
run
In the case of Java, that means:
1 Writing source code
You write .java files in a text editor, observing the right filesystem layout (file name = class name, directory corresponds to package etc.). You already have that covered.
2 Compiling the code
You compile the code using a Java compiler, possibly building a JAR or WAR file (depending on the type of application you are writing). You can do that manually by directly invoking javac (see for example Java - compile from command line - external jar ), but you should really use a build tool. The best tool to get started is probably Apache Maven or Gradle.
The basic idea is the same with both Maven and Gradle: You write a build file, which essentially describes your project and how to compile it (a POM file in the case of Maven, a build.xml for Gradle), then you can build by just invoking the build tool. The build tool takes care of all the nitty gritty like invoking javac etc. Most importantly, both also perform dependency resolution, meaning they can automatically download and use libraries that you use in your code.
3 Running
Finally, you run the program from the command line. How to do that depends on the type of program: A simple executable (or a Spring Boot application) can by run using java -jar myprog.jar, a WAR file must be deployed to a Servlet container (such as Apache Tomcat).
I hope this gives a general overview of How do I develop without an IDE?. For more details, look for specific questions here on Stackoverflow (or elsewhere), read the docs, and if all fails ask a more specific question here :-).
I agree with #sleske : if you really want to learn the language, it's good to start with a text editor. Later on you can use an IDE but by then you will know how the build process works and what exactly the IDE is doing. There exists no magic in coding. If something works but you don't understand why, it will certainly fail one day :)
Maybe some nice feature: I use Eclipse and added a vim plugin :)
And if you learn some useful shortcuts you can write code really fast (without a mouse)
You should download IntelliJ directly:
certain best practices like static import make your code more readable because you read it with a smart IDE. If you read code just with vim, the navigation between classes is not possible.
you have an easy access to a terminal and perform certain Maven or Gradle commands here.
I would not say the same with other languages (css, html).
I set out to install some fast matrix and BLAS libraries for Java, and settled on MTJ (backed by netlib-java) based on the results of Java Matrix Benchmark. I believe I have everything installed via Maven, but I can't find any credible documentaiton for these libraries.
The logical starting point would be the github pages:
MTJ
netlib
...But I can't find a link to any tutorials or javadoc beyond the incredibly terse MTJ wiki section on Github. Netlib's source appears to be in fortran (with F2J as a compilation step) so I can't crawl directly though source in lieu of javadoc, either.
To make things even more baffling, there appears to be some sort of Javadoc for MTJ out there hosted by a German university for some reason, that references packages (like nni.BLAS) that don't appear to be part of the MTJ library that Maven made for me. There's another even sketchier Javadoc hosted somewhere inside the University of Tennessee that, while having no apparent connection to the netlib-java project, does somehow have a Javadoc page that seems to explain the three extra integer arguments that netlib-java's DGEMV implementation uses (offsets of some sort?). If I look at the fortran documentation inside the netlib-java distribution for DGEMV, it has the eleven standard arguments that I would expect from DGEMV.
So here are my questions:
1.) Is there official documentation for MTJ/netlib? If so, where?
2.) If there is no official documentation, are there any other resources out there that would allow someone to learn to use this library? If this project isn't used exclusively by the developers, then people are learning to use it somehow. How?
3.) If a Java version of netlib's 11-argument DGEMV isn't installed as part of MTJ via Maven, then what is this 14-argument thing on my hard drive?
Thanks.
If you download MTJ via Maven, you can also download the Javadoc and source jars at that time. (IntelliJ IDEA will do this for you automagically.) The jar is called mtj-1.0.2-javadoc.jar and contains comprehensive Javadoc. Once upon a time, this seemed to be available on a website, but that site seems to be gone.
The closest I've seen so far:
http://en.wikipedia.org/wiki/Matrix_Toolkit_Java
Here is link to jar archive with complete javadoc of latest stable MTJ. Just unzip it with tool such 7zip or similar. I agree that lack of guides related to this library might be dauting.
I have created a site for mtj 1.0.3-snapshot on divshot.io:
http://mtj103.divshot.io/
Hope this helps.
I want to write some plugin to analysis Java source code. Which part of eclipse's plugin I have to know? I know this is a stupid question, but I really don't know where I have to start and I don't have too much time. I am not an actual programmer, I am a computer repair technician. So I just can write plugin (I love it) in spare time.
I am really grateful if someone give me a few pointers.
I didn't mean to be snarky above. So, I'd first recommend getting to understand the Eclipse architecture, plugin model and APIs. Here is an old, but still relevant tutorial:
http://eclipsepluginsite.com/#
It doesn't go into JDT at all, but does give you an idea about Eclipse plugins in general. So, once you understand that tutorial, you can move on to JDT:
http://www.vogella.com/articles/EclipseJDT/article.html
You'll need to master quite a lot -- the Builder API to hook into the incremental build process and get notified when files change, the IResource type hierarchy to get to the source files, the Java AST classes (there's a big bunch of those), some quirks concerning type bindings, etc. There is no simple pointer to give.
There are few open source projects/APIs/libraries that we use in our project (Spring, Struts, iBatis etc.) and I want to understand their design and how they work internally.
What is the best way to understand these projects? Note that I am already using these libraries in my project. And I know the input-output interaction/configurations for these libraries. What I don't understand is how these APIs/libraries work internally.
The problems I face is:
Finding the entry class of the library. Is there any way I can know the entry class for the library - something which is kicking the whole API?
Tools/Plugins to use in Eclipse to get an overview of the design of the library. Going through each and every class of the library, can be a very daunting task. Is there any tool you would like to recommend which can generate the class diagrams of the API in Eclipse.
Thanks in advance!!
UPDATE: I need some inputs on eclipse plugins which can help me in getting an overview/class diagram of the library
I always use the same strategy for this: I never try to "understand" the code base as a whole, and I usually try to follow the request flow. I read enough of the documentation to determine what is necessary to use the application, and I read that code (Keep all source code loaded in your IDE).
For example, in struts you'll be installing a servlet filter in web.xml. Start reading the filter and follow the path a single request takes through your stack.
Likewise for spring, there are two main entry points, the filter and "getBean", both of which are mentioned real early in the documentation. Read those two.
For both of these cases you'll find one or two classes that represent the "core" of the framework real quickly. Read those really well and let actual use cases & needs drive your further exploration.
Approaching "understanding" of an open source library (or any other code base for that matter) by trying to find all the pieces is usually not a very good way of approaching these things, it will usually just lead nowhere because a lot of these things contain too much code. When following the request flow I find making diagrams can also be quite distracting, it tends to draw attention/focus away from understanding (and since my understanding increases rapidly most of them are out-of-date even before they reach the printer).
Nice question!!!, what I've done, specially in the case of Spring, apart from consulting the Documentation and their API's is to attach the sources of the project to my project on Eclipse, that way I'm able to navigate through the source code, not just the API. Its been quite helpful specially in the case of the Spring-Security project, there were some concepts that I just couldn't understand until I inspected the source code.
That's one of the advantages of using Open Source libraries.
Regards.
Tools like Structure101 (http://www.headwaysoftware.com/products/structure101/index.php), and Lattix (http://www.lattix.com/) let you analyze code and produce architecture diagrams / dependency matrices.
This is not exactly class diagram - the main focus is on layering. So the entry point is usually the topmost layer.
But then again, as I specified above, you will notice that some libs are just a mess, and these tools will not be helpful enough.
See the S101 online demo: http://www.structure101.com/java/
This for example is the Sonar project architecture: http://www.structure101.com/java/tracker/sonar/1.11.1/arch.html
Your best bet for those three would be to consult the official documentation (make sure you are looking at the version you are using) or to get a book on the technology.
Most APIs don't have a class with a main method; they're running in the webserver called by the server itself. Unless they're running as their own server, they won't have a main method.
I've had several classes - university level - on Java.
However, what these classes lack is some practical approach to Java - or, to programming as a whole. Things you can only learn in a business.
However, since I am not allowed to use Java on the workfloor, I don't get to learn this now - even though I would like to.
So I guess what I'm asking for is any number of plain have-to-know Java resources. Things concering, for example, what Ant is and why and how to use it; using revision control systems from your IDE; standard Java libraries you would use often ... Anything that would help with actual software development, really.
As some side information, I've been using Eclipse for about four years now, and I feel at home there.
I have a system that works fairly well for class assignments and for projects as well. Firstly, I create one Eclipse project per class. This way I can re-use classes from previous assignments. You can also customize your classpath by adding another project as a library.
I use the Maven plugin for Eclipse M2Eclipse. Not only does this give you the ability to search for libraries and add them easily but the exec:java plugin is an easy way to execute your code from the command line. It's helpful because when it executes your code, it uses a classpath that includes all linked Maven dependencies. If you aren't using external libraries, you might not need Maven but I've found it to be helpful to learn in preparation for the job market. It's fairly simple to start with plus there are a ton useful plugins for open source projects.
Next, for revision control I recommend Subclipse. You can get a free SVN account with a single login from Unfuddle.com. Link that up to your Eclipse environment and Import your project.
When I want to get a particular class specification, I go to Sun's Java documentation.
Another excellent resource that will certainly give you the reference material (searchable!) to answer any java question would be this torrent containing ~100 ebooks on Java, sorted by directory on various topics (like Ant, Eclipse, or Swing).