Android: No virtual method position(I)Ljava/nio/ByteBuffer

[dbrgn]

Since version 0.8.19, our Android CI (using Android 5 and 6 devices) started failing on a msgpack test. Here's a simplified reproducer:

@RunWith(AndroidJUnit4.class)
@SmallTest
public class MsgpackTest {
	@Test
	public void testPutString() throws Exception {
		ByteArrayOutputStream out = new ByteArrayOutputStream();
		MessagePacker packer = MessagePack.newDefaultPacker(out);
		packer.packString("hello android");
	}
}

The error message:

java.lang.NoSuchMethodError: No virtual method position(I)Ljava/nio/ByteBuffer; in class Ljava/nio/ByteBuffer; or its super classes (declaration of 'java.nio.ByteBuffer' appears in /system/framework/core-libart.jar)
  at org.msgpack.core.buffer.MessageBufferU.resetBufferPosition(MessageBufferU.java:70)
  at org.msgpack.core.buffer.MessageBufferU.putBytes(MessageBufferU.java:232)
  at org.msgpack.core.MessagePacker.addPayload(MessagePacker.java:1073)
  at org.msgpack.core.MessagePacker.addPayload(MessagePacker.java:1043)
  at org.msgpack.core.MessagePacker.packStringWithGetBytes(MessagePacker.java:659)
  at org.msgpack.core.MessagePacker.packString(MessagePacker.java:732)
  ...

This is most probably due to the changes in #514 (cc @ppkarwasz). The test succeeds when running with msgpack-core version 0.8.18.

[ppkarwasz]

I believe the library must have been compiled against the wrong JRE (i.e. Java's 11 JRE was used instead of Java's 7/8): in Java 8 the classByteBuffer inherits the position method from Bufferand has a return type of java.nio.Buffer. On Java 11 the method is overridden with an implementation that returns java.nio.ByteBuffer.

@dbrgn: can you compile the library from source and check if it still fails the tests?

[bananaumai]

I also faced same issues. I'm using this library for Android Project. As @ppkarwasz said, jvmTarget is configured as 1.8.

[dbrgn]

@dbrgn: can you compile the library from source and check if it still fails the tests?

My local Java version:

$ java -version
openjdk version "1.8.0_232"
OpenJDK Runtime Environment (build 1.8.0_232-b09)
OpenJDK 64-Bit Server VM (build 25.232-b09, mixed mode)

I compiled the library locally:

./sbt publishM2

Then I added the local maven repo to my gradle file:

repositories {
    ...
    maven { url "/home/<user>/.m2/repository" }
}

...and finally forced msgpack to resolve to the snapshot version:

configurations.all {
    resolutionStrategy.force 'org.msgpack:msgpack-core:0.8.20-SNAPSHOT'
}

With that configuration, the test passes, so I think you're right. Maybe you can release a fix?

[ppkarwasz]

@xerial, can you make another release? Version 0.8.19 is almost certainly compiled against JRE 11 and linking problems occur, when using another JRE.

Maybe it is possible to setup Travis CI to run the test against the jar file, so oversights like this don't occur?

[xerial]

Got it. Thanks for the investigation.

We can add such an integration test using GitHub Action. First, I'll try to automate the release process to make sure to produce Java8 compatible jar files.

[xerial]

Released 0.8.20 built with jdk8.

[dbrgn]

Tthank you!