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.

CodePudding user response：

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 Java 8 u192 is years out of date.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.

CodePudding user response：

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.

CodePudding user response：

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.