Our enterprise code only compiles on Java 1.6, I tried 1.7, but it lead to horrible compilation problems that we can't resolve at this time. We use IBM RAD for our IDE and Websphere 8.5 server to deploy the EAR on our local machines. Would there be an issue to keep compiling with 1.6, while JAVA sends out new updates in the future?
We use DB2 with JCC4 for DB.
There will be no more updates to Java 6. As per official page you would have to pay Oracle to send you updates to Java 6 (and I'm not sure if this is even possible any more):
Oracle offers updates to Java 6 only for customers who have purchased Java support or have Oracle products that require Java 6.
Since Java 12 you can't even compile down to Java 6 (see JDK-8028563 : Remove javac support for 6/1.6 source and target values.
On the other hand Java 6 is very stable. There is certain stability in death...
Related
I have a program for work that I'm told will only use Java version 8 update 192 to run correctly. When I downloaded eclipse, it's suggesting that I use JRE 17.0.2 but I recalled my coworker saying I need Java 8 update 192 otherwise it won't work. Does the JRE version matter? Is it irrelevant?
Perhaps I need to download JRE 8.192? I'm not sure. Any help would be appreciated.
I have a program for work that I'm told will only use Java version 8 update 192 to run correctly.
I would doubt the accuracy of that statement. I would say that someone is making a statement without evidence ... if that is what they actually said.
Maybe a more accurate statement is that the program is only known to run on that particular version ...
Anyway, it will probably run on a later version of Java 8, or Java 11. Java 17 is less certain because of the issue of package sealing / blocking of access to internal packages that occurred in Java 16. (Some of the sealing / blocking started in Java 9 ... but there are easy workarounds ...)
Q: Do you need a JRE?
A: No. A JDK will work just as well. (A JDK distro includes a JRE.) But unless there are strong counter-indications, you need the latest version of Java 8, 11 or 17. Java 8 u192 is years out of date.
The only way to be sure that the application will work on a particular version of Java is to try it. In general, there are no shortcuts.
Java 8 is still available, as the first Long-Term Support (LTS) version. The current release is Update 331. I would suggest starting with the latest update of Java 8.
Be aware that Java 8 is not receiving regular updates for the public except for critical security patches. You may want to consider paying for a support contract from any number of vendors such as Azul Systems or Oracle to get support including possible additional updates releases through the rest of this decade.
Generally Java apps will run on later versions of Java without any modifications needed. The Java team at Oracle and the OpenJDK community place a very high priority on preserving that compatibility.
However, there are exceptions to the compatibility policy. In particular: Java 9 introduced the Java Platform Module System which caused some problems in some apps. And in later versions of Java some libraries that were previously bundled are now removed. Some of those removed libraries were transferred to the Jakarta EE project at the Eclipse Foundation. Some were abandoned for lack of interest such as CORBA.
Some few parts of Java that were for years marked as “deprecated for eventual removal” have now been removed.
If you consider moving beyond Java 8, I suggest your first step be sitting down to read through the Release Notes for every release of Java. They are quite well-written. They should alert you to any issues that may affect your app.
FYI, Java 17 is the latest LTS version. Java 18 is current.
As in the other answers, an application built for Java 8 will probably work fine in Java 17, with some caveats, but if you absolutely need the final product to run under Java 8, go get a real Java 8 runtime and set it up in your IDE. Building a Java application for any specific Java version is best done by having an actual copy of that runtime present, preferably a JDK. By having an exact version of its standard library to compile against, you can avoid accidentally referring to packages, classes, and methods added to, or removed from, later versions. You can get an OpenJDK build of Java 8 from https://adoptium.net/?variant=openjdk8 . Be sure to ask your co-worker why they're mentioning an outdated patch version.
Additionally, keep in mind that Eclipse is itself a large Java application. Running it requires Java, and a growing number of downloads include a Java runtime for that simple reason, even the ones that do not include Java development tools. You don't have to compile your code against that version of Java, though--you probably don't even want to since JDK downloads will include JavaDoc for the standard library, among other useful extras.
Here's the thing:
Me and my teammates are now working on a Java project, but I'm almost new to Java development. The thing is that I recently updated my local Java version to 15.0.2, however, they created the project with JDK 1.8 (Java 8 perhaps?).
We are worried that this might cause some conflicts since our Java versions are not corresponding, and I'm also not familiar with the relationship between Java version and JDK version (Just like Java 8 and JDK 1.8).
Could somebody give me some explanations of this? Thanks a lot!
We are worried that this might cause some conflicts since our Java versions are not corresponding ...
Yes, you could run into problems:
There are significant differences in the Java language and Java standard class libraries between Java 8 and Java 15. Code written for Java 15 using Java 15 may not compile on Java 8.
Java 8 and Java 15 tool chains produce compiled code with different classfile version numbers. Code compiled for Java 15 will not run on a Java 8 platform.
It is possible to work around these problems, but it is much simpler if all project members use the same Java version.
If you are new to Java, my recommendation is to install and use Java 8. Note that it is possible to have different versions of Java installed simultaneously, and use different versions for different projects.
... and I'm also not familiar with the relationship between Java version and JDK version (Just like Java 8 and JDK 1.8).
It is pretty straightforward. Java 8 is JDK 1.8, Java 9 is JDK 1.9, and so on. This started with Java 5 / JDK 1.5
The weird numbering is a result of a Sun Management / Marketing decision when naming Java 5:
"The number "5.0" is used to better reflect the level of maturity, stability, scalability and security of the J2SE."
Source: https://docs.oracle.com/javase/1.5.0/docs/relnotes/version-5.0.html
(You could also say that the people who made this decision didn't understand the principles of semantic version numbering.)
We currently use Glassfish 4.1 and I really want to use Java 8. Will Glassfish 4.1 work with Java 8 or will I have to upgrade my application container?
Simple answer,
Yes.
GlassFish 4.1 will work with Java 1.8.
In general: updating the jvm version alone rarely leads to issues.
Keep in mind that a lot of work goes into making sure that new Java versions are backwards compatible. And most importantly: a new jvm can always run byte code compiled for an older version of Java. The other way round (upgrading your application server for example) is much more likely to cause significant problems.
So, the (unspecific) answer here is: just try it. And for the record: Java 9 (or newer) with the new module system is a completely different story. But at least for now, the corresponding checking can be disabled on the command line.
Of course, there can be subtle issues for large applications. A new jvm may use different defaults for say, garbage collection settings (or use a different gc in the first place). That can of course change the runtime characteristics of large applications running in a large stack.
The best (and easiest) approach for determining whether Java version 'x' will work Glassfish version 'y' is to refer to the Release Note for that specific Glassfish release.
The Release Note will have a section titled Hardware and Software Requirements, and within that a sub-section titled Required JDK Versions.
For Release 4.1 the answer is:
GlassFish Server Open Source Edition Release 4.1 requires Oracle JDK 7
Update 65 or later, or Oracle JDK 8 Update 20 or later.
Notes:
The word "later" in the part stating "Oracle JDK 8 Update 20 or later" is ambiguous, but it is referring only to the update level for the specified JDK version. Do not interpret "later" as implying that Glassfish 4.1 might work with Java 9 or higher. It would be much clearer if the wording was:
GlassFish Server Open Source Edition Release 4.1 requires Oracle JDK 7
using Update 65 or later, or Oracle JDK 8 using Update 20 or later.
It is incorrect to state that "Glassfish 4.1 will work with Java 7 or Java 8", because in both cases a minimum update level is also required.
You can also get the minimum JDK requirements from Glassfish itself. Under the root of the unzipped download in a file named README.TXT there is a section titled 0. Prerequisite. For Glassfish 4.1 it is worth noting that the information given conflicts with that in the Release Note!...
GlassFish 4.1 requires Oracle JDK 7 Update 65+ or Oracle JDK 8 Update
5+.
In the odd cases where the requirements in the documentation conflict I'd always be inclined to choose the higher update level, and most of the time this is unlikely to be an issue.
I compiled my old JAR files in Java 7 and my production environment has Java 8. Is there anything I need to be careful about directly deploying the JAR files onto Java 8 Environment? I test ran them on Java 8 and it worked fine. Could I encounter any problems or should I be fine? I was wondering this because I was debating removing Java 8 and installing Java 7.
EDIT: A side question: Do companies update their code when they update their Java version? I can't imagine how painful this must be so have your app working on a previous version and then completely fail on the new version.
I was wondering this because I was debating removing Java 8 and installing Java 7.
I assume you mean the other way around?
Java attempts to maintain backwards compatibility as far as it can, so theoretically at least you should be ok.
In practice however, issues do sometimes come up, so I'd advocate testing thoroughly. These may be due to regression bugs, or (more likely in my experience) buggy code that might have run fine under Java 7, but not under 8. (FWIW, I had a couple of FX apps that mixbehaved under 8 but ran fine under 7, it turned out both were due to bugs in my code that coincidentally had no unusual side effects when running with 7.)
Usually, there should be no problem. Otherwise you would have a hard time to use any third-party libraries not explicitly compiled for Java SE 8.
I recommend to run your automated tests on a continuous integration server such as Jenkins using Java SE 8 and see if you have any issues.
It is safe to package Java 8 application with jar dependencies compiled with Java 7. Given that said, however, keep in mind differences in JDK 7 and 8, that can result the same Java code could behave differently when running on JDK 8 vs JDK 7 (refer to JDK 8 release notes)
I am developing software on a machine with the latest JDK update (e.g. jdk1.6.0_24). Do the machines where the software is running also need the corresponding JRE update version? Or would it suffice to have an older version (e.g. jre1.6.0_10) installed?
Just the major version (1.6.0) needs to match for Java. It's fine if the update version (10 and 24) is different, the spec is still the same. Although ideally the place where the software will run has the latest update for bug fixes, security fixes and performance improvements.
You do not need to worry, if both are the same major version, which is your case, both are Java 6.
However, if you are releasing your software to a client machine, I would suggest you to read the incompatibilities between Java 6 and other Java versions. And, if there is an incompatibility, mention it in your product document.
Please read this document: Java 6 Compatibility