是否可以编译较新的Java版本（9,10,11）以在较旧的平台（例如Java 8）上运行？

Question

Is it possible to develop using newer Java (eg 9, 10, 11 etc.) versions, and have that Java be compiled down to some older version - such as Java 8?

We would like to use the new features of newer Java versions, but our code needs to run on a Java 8 platform.

If it matters: we are building with Maven.

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Phrasing it in Javascript fashion:

Does there exist a Babel Polyfill equivalence for Java?

Answer 1

Not necessarily. If you have code that uses packages/syntactical structures not defined in previous versions, the program will fail to run/compile.

Think of it this way. Before Java 8, there were not lambda expressions. So if you create a lambda expression in Java 8+ and then attempt to compile it in java 7, the compiler will be like: What is a lambda expression?

In short no. However, you can go the other way. Compile code written in a lower version using a higher version... for the most part.

Answer 2

No - you cannot use new features on an older JVM; the bytecode is incompatible .

You can absolutely use the newer versions of Java to compile down to a lower version, with some caveats around modules.

If you need the new features of newer Java versions, then it's time to migrate to a new version; other than that, where you are will be fine until you require support from Oracle.