Knowing C++, how long does it take to learn Java?

Question

I am a competent C++ developer. I understand and use polymorphism, templates, the STL, and I have a solid grasp of how streams work. For all practical purposes, I've done no Java development. I'm sure some of you were in a similar situation at one point when you had to learn Java. How long did it take you to become a competent Java programmer?

Answer 1

I went the opposite way. Started with Java, then moved to C and C++. For my own personal experience, it was much easier to learn Java than C/C++ (C++ especially).

Java in many ways is meant to be C++ with many of the undefined and unnecessarily complicated portions removed or simplified. IMHO, it had great success with that goal. As a result it's a very easy language to learn and use. Especially for someone who is familiar with C++.

The actual time it will take is very dependent upon the person learning the language. However, I think it's safe to say it will take less time to become competent in Java than it did in C++.

Answer 2

Shouldn't be too bad. The syntax and classes should be very easy for you to grasp. There are some differences but none of it is too challenging.

The hardest part is more about learning the packages, since those will be different. The built in Java classes and functions, and then to use Java in a practical manner, you'll need to learn J2EE or whatever you might be actually using it for. The latter part will probably take more of your time than the language itself.

Answer 3

I know C++, and had to work with Java once and picked it up in 2 weeks. Of course there were quite a few surprises but it's easy.

Answer 4

I think there are two approaches to meaning of term "competent Java programmer". If it is about lexems, syntax and terms of OOP I began to completly understand Java before 2 (two) days of learning. But firstly you will be charmed by impossibility to shoot your own leg ;) But if it is case of embeded class system (i.e. packages), APIs references, tips-and-tricks and etc., it takes about half-year to feel yourself friendly with Java. I think.

Answer 5

I too learnt C++ first and then Java. It took very less time as I was already familiar with OOPS concepts. In the initial phase of learning I was really happy with new concepts in Jave like garbage collector. I referred The Complete Reference by Herbert Schildt and it did help me to get the syntax quickly.

Answer 6

Back in 1995 when I did it, it took me about half a day to get comfortable with the tools and basic ideas, a day or two to get the language, a week to get the more obscure parts of the language (there were less of them at the time) and a month to get the libraries (there were WAY less of them at that time).

Now I would guess that the tools and basic language will take as much time, a couple of weeks to a month for the obscure parts of the language (depends on what parts you hit, and when). The basic libraries will be a month to two months (java.lang, java.util, and a few others). The remaining class libraries 6 months to forever depending on what you need to learn and how often the keep updating them :-)

Answer 7

If you're already a competent programmer (especially in C++) then Java doesn't take long to learn at all. The books I would recommend (in order) for anyone who wants to learn Java are:

• Head First Java
• Thinking in Java
• Effective Java

You may find that you zip through Head First Java rather quickly, given your experience. For that reason I suggest you check it out of the library and skim it before moving on to Thinking in Java.

Also check out Sun's Java Tutorials.

Answer 8

I have C++ background. Picking up Java took me few days - the language seems really simple - at least its basis. I still consult my Java guru - google quite a bit, but it's usually a matter of exploring API and standard libraries. Java has some annoyances, but you should spot most of them them easily and quickly.

I was recommended Thinking in Java (there's an ebook for free), but was never persistent enough to read through it. I don't write rocket-science code in Java and to do it, my skills are sufficient.

Having said that, it would be good to have better formal knowledge of the language. At the moment I'm thinking about studying for SCJP, which seems a sensible way of learning, plus you will get well-recoginized programming certificate once you pass it (I've heard it's not worth much, but still it may be a motivation...).

You can also try Java Black Belt - the answers frequenty surprises me. After taking few tests I wonder how my programs even compile, which suggests I'm probably not the most competent Java programmer around :)

Answer 9

I think that learning the language is not difficult. In fact, I used to be a full time C++ developer, and at some point I started writing Java code. But the thing is that I don't remember ever learning Java, so I guess I just figured it as I went. I've been doing full time Java for a long time now.

If you are well familiar with C++, you may want to read a list of the major differences (e.g., everything is dynamically-bound) and then start practicing on an environment (just download Eclipse). The small differences are the main thing you would have to get adjusted to.

Now that Java supports generics, one of the major switching pains is gone. Multiple inheritance, while not supported, is not a big deal if you get used to interfaces, and in fact having interfaces rather than abstract classes with PVFs improves readability.

To me Java is a nice and friendly and relaxing sandboxed version of C++. I don't have to worry about GPFs, I don't have to worry about memory leaks, I don't have to worry about messing with pointers. However, don't let that confuse you, there are still plenty of opportunities to screw up royally, and they're sometimes even nastier to detect.

Just take the leap. If you have the instinct, it shouldn't be a problem.

Answer 10

C++ to Java: 1 week. Java to C++: 1 month.

Answer 11

How would you define competent? For my money, most professional (as in they do it for money) Java programmers never manage to reach competent.

Answer 12

I started from C++ and learned C#/.NET. That didn't take long. As C#/.NET is developed very near to Java (they used many of Java's base techniques such as GC, reference classes, JIT, ...) I think it is not that hard to learn Java.

Answer 13

These days, a programming language derives much of its power from its libraries and accepted idioms.

While it takes relatively short time to learn the Java language, learning to use the available libraries (collections, io, etc.) effectively will probably take significantly more time.

Answer 14

As Tom Hawtin wrote, the key issue is how you define competent.

You'll be able to pick-up the language fairly easily, but it's the idioms and the libraries that you will have to learn. And there are quite a few differences between niches you work in (e.g. embedded or enterprise), and between libraries that supposedly solve the same problems. Here are a few examples:

1. In business/enterprise apps, you generally work with databases. There you can have:

   • plain JDBC
   • SQL mapper (iBatis), wrapper around verbose and repetitive JDBC
   • ORM solution (Hibernate), with a philosophy of it's own

2. With desktop UIs, you have two competing platforms:

   • Swing, a part of JRE
   • SWT/JFace, from Eclispe foundation, originated by IBM, with native UI support

3. Web frameworks are too many to mention, with different ideas of representing the UI, configuration, folder/package structure etc.

4. DI (dependency injection) is common in business apps, either by 3rd party frameworks like Spring, or as a part of EJB3 standard. But, I don't think it is ever used in embedded set-up.

It would be fair to say this is just a tip of the iceberg.

Answer 15

I would go with six to eight weeks.

Answer 16

Shouldn't take you more than a day or two to learn the language, but you might have to spend a few weeks on the class library: how to use collections, the concurreny package, reflection, logging, swing/awt, dynamic proxies, MBeans etc.