Java backward compatibility ?s

[Yu Chen]

Not sure which categoty it fit better, but let me ask some other backward compatibility ?s.
- If codes were compiled on JDK1.1, will it run correctly on JVM/JRE1.4.0?
- If codes were compiled on JDK1.2, will it run correctly on JVM/JRE1.4.0? Is this
better than the previous case?
- If codes were compiled on JDK1.3, will it run correctly on JVM/JRE1.4.0?
I am trying to analyze the impact of migration from Netscape4.x (with JRE1.1.1) to Netscape6.2.1(with JRE1.4.0Beta).
Thanks in advance!!
-yc

[Roy Ben Ami]

background compatiobality is complete as far as i know.
anything u compiled in 1 2 or 3 would work perfectly in 1.4 .
however the opposite wont work.

[Cindy Glass]

yc,
Please change your name to be compliant with JavaRanch's naming policy.
Your displayed name should be 2 separate names with more than 1 letter each. We really want this to be a professional forum and would prefer that you use your REAL name.
Thanks,
Cindy

[Dale DeMott]

Hmm.. Sounds like you are getting your wording mixed up. Backward compatibility is when your code is able to run in previous versions of systems. In this case we are talking about our JVM as a system. So if you were compiling your code in 1.3 JVM it would run in 1.2 JVM. Backward compatibility depends on the methods you are using and if those methods are still used in the new JVM [not deprecated]. Or do you really mean forward compatibility? This is when your code in your code in 1.2 JVM would run in 1.3 JVM. If you mean this then the question is mostly yes. Again it depends on the methods that you are using and if those methods are deprecated or not. In both cases you want to make sure all the methods you are using are not deprecated. Usually you will get a warning when things are deprecated.

[Dirk Schreckmann]

Hello,

A follow up question:

When a method has been deprecated, does Sun publish data on when (in what new version of Java) that method will no longer be available?

Thank You,
-Dirk Schreckmann

[Rob Ross]

The truth is, no one knows that. As APIs evolve, methods will get deprecated to encourage developers to start using other methods. It's a good system though; on other platforms/libraries, sometimes you don't get a warning. You just get a bunch of compiler errors when you try using the latest version of the library.
Deprecation is like the yellow light on American traffic signals...it's letting you know that a red light is coming. So if you're a dilgent programmer, as soon as you get a deprecation warning during a compile, you start planning a migration to start using the replacement method. Deprecation also gives you time to do this planning and migration. But the longer you wait, the more likely it becomes that a new version of the JDK will no longer have the method.
However, I'm not aware of a deprecated method that has actually "gone away" yet...but it is bound to happen at some point. There's just no way to predict when that happens.