From PHP to Java. Any advice? [closed]

Question

I wouldn't try to learn an IDE at the same time as learning a language. An easier transition would be to stick to your shell and habitual text editor, and use the following shell-friendly tools:

• ant, for organising your project, running automated test suites, incremental compiles
• BeanShell for interactive testing, trying things out quickly
• A quick trick: javap from the commandline will give method signatures for any class in the standard library. Similar to php -r but gives more information since Java is typed.

The online documentation for Java is precise, professional, and consistent in tone and format. Unlike in PHP where all of the functions are in one flat namespace, the standard libraries in Java are class hierarchies. You've got to know your way around that standard library, which means knowing hierarchies + responsibilities: for example you've got to know that java.util.List is a subinterface of java.util.Collection with the addition of a concept of ordered entries. With that information in your head, a google search for java.util.List will take you to the Javadoc for the class, and the Javadoc will tell you exact method signatures and link you to a selection of concrete implementations.

Some miscellaneous distinctions:

• Strings are sequences of characters rather than sequences of bytes. Absolutely the right way of doing it.
• Systems produce and consume streams (of bytes or characters) rather than byte buffers. For example, if you wanted to filter the output in PHP, a standard practice is to ask ob_get_contents for a byte buffer then to transform the whole buffer. In Java, you add a filter to your servlet that transforms the output a byte or a character at a time. It's a bit imposing to work with initially but it's simpler and more Lego-like when you get used to it - your stream processor doesn't have to know where things come from and where they go.
• Almost everything useful is an interface, and creating an instance of an interface can be tricky, non-standardised, and not always well-documented. In PHP, you can get up and running with XML with new DOMDocument(). In Java, org.w3c.dom.Document is an interface, so new() won't work. Javadoc is very precise about how interface instances behave once they come into existence, but it can be quite coy and prudish when you're trying to find out how an object is actually born. Very often, you'll have to look for tutorials and code examples and copy-paste a piece of boilerplate that gives you an instance of DOMDocument or java.sql.Connection or whatever. One reason frameworks like Spring are popular is that they separate out the ugly object-creation code and present you with a world where interface implementations are just magically there.

I actually switched in the opposite direction. I found that Java works very well in a large company where you might be working on a single component, handing it off to someone else who integrates that component into a larger system, which is then packaged and handed off to a separate operations team - that's where all this indirection and configurability (FactoryBuilderFactory type abstractions, web.xml files, etc) makes sense and does something useful. In a small company where the programmers are the ops personnel, Java is a lot more work. With Java, you'll have to get used to concepts like starting up the Java process, monitoring the Java process to make sure it stays up, monitoring the Java process to make sure that it doesn't go into a coma where it's alive but not responding, shutting down and restarting the Java process with minimal disruption when you're updating code, etc, etc. If you have separate ops personnel, that's fine, it's their job, they're very good at it. If you're a programmer, babysitting a Java process can be distracting and difficult to do well.

Start with the Java Tutorial

http://java.sun.com/docs/books/tutorial/getStarted/index.html

Then go buy Head First Java

http://oreilly.com/catalog/9780596004651

It will get you going pretty quickly in the language which is essential regardless of what you want to do.

Strictly speaking, you don't need an IDE to work in Java. I've been coding heavily in Java for well over a decade (and heavily on other stuff for over 25 years), and I don't much like IDEs. Perhaps that implicit indicator of my age is part of the issue :-) It's a trade-off, like anything else.

I'll plug Stripes as a nice simple framework, but mostly that's because it's relatively small and limited in scope. The large frameworks like Spring are "kitchen sink" ecosystems, and learning Java with one of those frameworks may smooth some of the difficult parts but leave other basic aspects mysterious. Again, it's a matter of personal preference.

It's good to have somebody around who knows the language. Oh, and to that point, make a friend of the Java API documentation. As platforms go, the Java API has its ups and downs but for the most part the documentation is at least pretty thorough and pretty accurate.

You'll also want to get really familiar with JSP and its relationship to Java and Java web service architectures, because that'll be what you'll relate to your PHP experience most directly (I'd think).

The best move I made was from Java to PHP.

Beware of complexity. Primarily, the key to great software is simplicity, and that is why PHP combined with a good framework kills Java.

With Java, you risk becoming a slave to your servlet container and framework. Choose the simplest most flexible framework. Controls and custom tags are the devil. You'll waste days learning things that were designed to make development quicker, but are ultimately too complex and inflexible. Java will slow development due to: complexity, compilation, and static types. You'll come to loathe null pointer exceptions.

Edit: Tools aside, Java and PHP are very similarly structured "C" style languages. Much more so than Python or Ruby. It is the static typing and complex tools that make Java so foreign.

I recommend hitting up JavaBat at here

It will give you some good ideas. It took me 1 solid year in a professional setting to get a very firm grasp on Java and I have been able to move into other OO languages quite easily once I had the thoughts beaten into me.

This appears to be a bit of an old post, but hey...

I moved from C# to Java and I've just started a role and am moving from Java to PHP...

First off: Java is awesome :)

• for your IDE get Eclipse, once you get used to it, you never have to leave the IDE (apart from SQL bits). It manages projects really well, you can download alsorts of plugins, such as SVN plugins. It allows you to run a Tomcat server within Eclipse and it will output errors straight to the Eclipse console.

• for the framework, I used Struts and Tiles and Torque for the ORM, took me a while to get my head around them, but once we made friends, I can't imagine any other way of developing. Although I imagine for a small project it would be a lot of overhead!

• agreed with an above post - get HEADFIRST JAVA, thats how I learnt and I used it for lots of other languages, they have a visual method of learning thats alot easier than pure textbooks - well for me anyway. I was up and running with in a day and confident within a couple of weeks I guess - but always learning :)

• yip Java is strict, but you come to love it, for me moving to loose 'ol PHP is a bit wierd.

• you will also need to download Tomcat to run your Java bits, its easy as to get running.

• Java organises all your classes very nicely, none of this 'require_once(some_text_file.php)' rubbish, just 'import myClass' and off you go.

• one of the things that annoys me is, there is no way of telling which JAR libraries you are NOT using, so after a couple of years working on a site, your lib folder can get a bit messy - specially if mulitple people are removing and adding functionality.

I could go on.

Paul