Binary10 – my blog with code

I have decided to describe installation process of Java Runtime Environment one more time, now I’m adding screenshots so it will be much easier to understand:

1. Go to http://www.java.com/en/download/
2. Click blue button, a new page appears:
3. After loading page, a download process should start automatically, if not click blue button again.
4. Now, the JRE installator will be downloaded, wait until it’s completed, then run it.
5. You will see this window:
6. Again, wait some time, the installer will download another installer, that will install JRE, it will be started automatically:
7. Click “Accept” and in next stage your JRE will be installed:
8. After finished installation a new window opens saying that it has successfully installed your JRE, click “Finish”.
9. You have installed JRE properly

Firstly, quick introduction: JavaMe (also known as: j2me, jme, java me, Java Mobile Edition, …) is a special version of Java (in fact it is “frozen” Java 1.3, maybe with some features) dedicated to devices with low computing power, we distinguish two configurations: CDC (palmtops, more powerful phones, …), CLDC (Connected Limited Device Configuration) – baisicaly every other phone.

Configurations include basic classes, and they are extended by profiles (MIDP – Mobile Information Device Profile), all new phones should handle MIDP version 2.0 (newer 2.1). Profiles provide classes to:

• handle screen (high and low level)
• multimedia features
• better connectivity (eg. HTTPS)
• and many more

Next, phone can also provide additional APIs, called JSR. JSRs extend phone’s powers (for example by allowing you to use bluetooth), they are not included in CLDC nor MIDP. Every JSR has it’s own number, so they are easly identified (bluetooth is called JSR-82).

All programs I’m going to write require MIDP version 2.0. That doesn’t mean you wont be able to run them on older phones, but you may not be able to use things that are extended in version 2.0, for example you won’t hear background music playing, or you won’t be able to initiate call inside application.

When writing program for mobile phone, you should remember, that it’s manufacturer is responsible for delivering appropriate runtime environment (JVM). Sometimes it is not written according to specification delivered by Sun. I have noticed, that Nokia models have some problems with some elements of GUI. I have also tested Samsung’s and Sony Ericsson’s, and didn’t have any problems with them (I have no possibility to chceck it on other phones, so I don’t know how it is with for example Motorola).

You can find additional info on wikipedia (as usual):

• http://en.wikipedia.org/wiki/Connected_Limited_Device_Configuration
• http://en.wikipedia.org/wiki/Mobile_Information_Device_Profile
• http://en.wikipedia.org/wiki/Java_Platform,_Micro_Edition
• http://en.wikipedia.org/wiki/Java_Community_Process

At most on Friday I’ll post information how to start new project in Netbeans, and start writing programs:)

Let’s begin with the most important thing if you want to develop in Java. You need JRE and JDK, you probably have JRE, because it is required by some websites to display (like banking, chats, games). But what they are?

• JRE stands for Java Runtime Environment, and it is basically software that allows you to run programs written in Java using JVM (Java Virtual Machine), if you have experience in programming in other languages, most of them are compiled to binary code, and executed directly by processor, that requires to compile different versions of programs for any other operating system or processor type. JVM acts like virtual machine (it just is a virtual machine), and executes compiled java program (java programs are compiled to bytecode)
• JDK is a set of applications that allows you to write programs in java, it provides you a compiler, loader, debugger and more useful tools.

More information here:
http://en.wikipedia.org/wiki/JDK
http://en.wikipedia.org/wiki/JRE
http://en.wikipedia.org/wiki/Java_Virtual_Machine

Getting JRE:

1. Go to http://www.java.com/en/download/index.jsp click blue button “Free Java Download”
2. Download file is used to download appropriate JRE, that will start after you run it.

JDK (quite harder):

1. Go to: http://java.sun.com/javase/downloads/index.jsp click “Download” near: “Java SE Development Kit (JDK) 6 Update xx”, where “xx” is latest java update, currently 12 (it’s on top)
   
2. Than select your OS, language, and confirm reading and accepting EULA.
   
3. If download didn’t start automatically click “jdk-6uxx-windows-i586-p.exe”
4. After JDK installation we can move to another point which is installing IDE (Integrated Development Environment).

Next step soon, after that we can start real codding:)