Some questions for j2me

Question

Dear all,

I do have some questions which always confuse me a lot.

(1) Why when we install j2me, we have to install jdk first? [for my understanding, they are independent 2 versions, one is of embedded, another is for desktop application]

(2) How to install the j2me environment into the phone or embedded device? Do we need to install the jdk firstly? (It seems that jdk cannot be installed on phone and embedded devices).

(3) what is the relationship among j2me, j9, phoneMe, jamVM...? When use this in the embedded devices, the pre-requisites is also the JDK? (you have to install the jdk firstly?)

Thank you very much!

Answer 1

A very rough outline...

1. You need the JDK to compile java code - J2ME provides an API for your application, but no compiler.

2. Your target devices will come with a JVM and J2ME environment built in, so no need to worry about this directly as a developer.

3. I think you've got two questions in here. You don't need the JDK on the target device; only when compiling your app. But see 1. - you do need the JDK to compile your app.

J9 and JamVM are VMs I'm not familiar with; hopefully others will chip in. Likewise on phoneMe.

See also the related questions on SO (over at the right of this page), especially this one.

Answer 2

For missing part,

J9 is JVM implementation by IBM. phoneME is open source implementation of Java ME (CLDC, CDC) by Sun Microsystems. I don't know about JamVM but, I can find it from web. It looks like SE JVM for light weight implementation.