If I had just made a dollar each time I heard this question...  *sigh*.

With the availability of so many different development technologies in Nokia's platforms today, sometimes is hard to decide which of them we should use to build our application, isn't it? There's Java, Symbian C++, Open C, Flash Lite, WidSets, WRT Widgets, Python, and the list is still growing.

This is good news for developers, since not everybody has the same technical background nor is developing the same kinds of applications; this means at least one of the technologies will fit our experience and purpose like a glove, and we are going to use it. On the other side, this may confuse newcomers to the wonderful but fragmented mobile software world. Usually it goes like this:

Question: "I want to write an application that opens a file and sends it out to a web server. What should I use to create it?"
Answer 1: "Java ME, FileConnection API"
Answer 2: "Don't bother, use C++ or you will get a lot of security prompts."
Answer 3: "Why use C++ when you can do the same with Python? C++ is way too hard!"
Answer 4: "Python does not run on S40, use Java."
Answer 5: "Do you really need all that jazz? Why don't you go with Flash Lite and use server-based persistence? Your application will look great!"
Answer 6: "Flash Lite is too fragmented. Use Java, but beware of the MIDlet signing issues or your app's user experience will be crap!"

Go check the Discussion Boards. It is crowded with examples of conversations like the one above. Having answered this question so many times before, I decided to summarize my answers in this blog, in the hopes of helping developers decide what use from the growing technology options pool offered in mobile devices these days. Please keep in mind that the following are my opinions on the subject; yours may differ and even prove mine wrong, but that's the beauty of interacting with people within a community. As the number of technologies it too big for a single post, I will continue my analysis in the upcoming posts. I will start off with the most popular mobile developmentp platform, Java ME.

Technology: Java

Good for:

• Productivity applications - Examples: sports trackers, expense control apps, Personal Information Management (calendar, phonebook, etc.).
• Games - Both casual and complex.
• Enterprise applications - These don't require fancy user interfaces. Using LCDUI and the standard packages can go a long way pretty fast.
• Rapid prototyping and proof-of-concept applications.
• Network applications - RSS readers, weather services, blogging applications, mobile versions of Web applications.
• Creating truly portable apps

Why? 

• Java and its mobile version are very simple to use and learn -  An experienced programmer, even coming from other C/C++-based languages, can get a pretty good working knowledge of how everything works in a matter of weeks and start producing applications quickly. This leads to faster time-to-market for Java ME apps.
• Applications are generally portable between S60 and S40 platforms - Although there are some differences in implementation, supported packages, audio/video formats and so on, those are few in number and thus easier to work around. You don't need to entirely rewrite your application so it will run on N95 instead of 6131: a few runtime checks and versioning tools will be enough.
• Game API combined with optional packages makes it a killer for game development
• Straightforward network API makes it easy to communicate with web services - The GCF (Generic Connection Framework) is a simple and unified way of using the network on Java ME applications. Once you learn how to do one kind of connection, you will have learned them all.

Bad for:

• Accessing device resources - Examples: SMS Inbox, file system, gallery, hardware.
• Multimedia applications - Examples: Video streaming players, audio and video recorders, camera applications.
• Performance-intensive applications - Scientific computing, image processors, video decoders, sound processors.

Why? 

• Java's functionalities depend on Java Community Process process: if there's no official, industry-standard API for what you want to do, you are out of luck. Example: accessing SMS inbox.
• Mobile Media API implementation is (too) highly modular, a lot of runtime checks are needed. Also, most functionality is implemented on the native side and then made available to Java's virtual machine, such as the camera access. This may have a serious impact on performance.
• Fine-grained control over video, audio and camera is generally not available. Although JSR 234 (Advanced Multimedia Supplements) tackles some of these issues, it still can't be compared to what's available on other technologies, and its device availability is still low.
• Access to the file system is provided by FileConnection API, but it's somewhat restricted and requires the midlet to be signed, otherwise multiple security prompts will be displayed, taking your user to tears (believe me). The signing process itself costs money and has some bureaucracy, so be prepared.

Next time I will cover the darling of all Internet programmers, now getting much of the attention on S60 platform: Python.

See you!