What version of Java does Cassandra 3 require

Question

The recommended version of Java for Cassandra 2.0 was Java 7. But which version is recommended or required for Cassandra 3 (specifically, version 3.5)?

Some information suggests that Java 7 or Java 8 are required; that is, that Java 7 is still OK:

• The Cassandra Wiki says:

Cassandra requires the most stable version of Java 7 or 8

• The change log for Cassandra 3.5 does not mention changing the required JRE. It does have a change (CASSANDRA-7028) to "Allow compilation in java 8". But allow is not the same as require.

Answer 1

Cassandra 3.0+ requires Java 8.

• The cassandra-env.sh script, used by the cassandra shell script, examines the JVM version and refuses to run if the JVM version is before 1.8.
• If you try to run code directly using one of the classes of the cassandra-all.jar using a Java 7 environment you will get a java.lang.UnsupportedClassVersionError complaining of Unsupported major.minor version 52.0.
• The META-INF/MANIFEST.MF file in the JAR indicates it was compiled using a Java 8 compiler: Created-By: 1.8.0_45-b14 (Oracle Corporation).
• The Datastax announcement about Cassandra 3 says that it requires Java 8.

In conclusion, the Cassandra Wiki is wrong and the Cassandra change log is misleading.