有没有办法在 Java 8 运行时中使用 flatc 生成的类？

Question

I have working code that runs fine in OpenJDK Java 9, but throws the NoSuchMethodError below when run in OPenJDK Java 8. Even when flatc is built on a system with Java 8 I still get this error. Is there any way to generate classes that will work in Java 8?

    Exception in thread "main" java.lang.NoSuchMethodError: java.nio.ByteBuffer.position(I)Ljava/nio/ByteBuffer;
at com.google.flatbuffers.FlatBufferBuilder.createString(FlatBufferBuilder.java:605)
at jeromq_and_flatbuffers.io.MonsterIO.writeTo(MonsterIO.java:54)
at jeromq_and_flatbuffers.io.MonsterIO.writeTo(MonsterIO.java:1)
at jeromq_and_flatbuffers.core.MonsterPublisher.sendMessage(MonsterPublisher.java:80)
at jeromq_and_flatbuffers.core.MonsterPublisher.run(MonsterPublisher.java:104)
at jeromq_and_flatbuffers.core.Main.lambda$0(Main.java:46)
at java.util.Optional.ifPresent(Optional.java:159)
at jeromq_and_flatbuffers.core.Main.main(Main.java:46)

I realize there were a number of NIO improvements in Java 9, but my network IT has constrained us to Java 8.

Answer 1

A solution is to either not use downloaded Flatbuffers 2.0.0 dependency from Maven central repo, which is built with Java 9 or higher. Instead, build Flatbuffers jar from source by downloading Flatbuffers source, then executing maven package in the top level directory, within a Java 8 environment. Then take the jar in target and use that in your app. This got me past the error.

A better solution is to use Flatbuffers 2.0.2 or later, which fixes the problem.