Java – Unsupported version error using JTDS with Scala

javajtdsscalaspray

I'm trying to use the Java JTDS driver to connect to my database in Scala . However, whenever I try to use it I get an error that the version(of java?) is wrong.

java.lang.UnsupportedClassVersionError:
net/sourceforge/jtds/jdbcx/JtdsDataSource : Unsupported major.minor
version 51.0

object DaoDriverAdaptor {
  import java.sql.{DriverManager, Connection}

  private def loadDriver() {
    try {
      Class.forName("net.sourceforge.jtds.jdbcx.JtdsDataSource")
    } catch {
      case e: Exception  => {
        println("ERROR: Driver not available: " + e.getMessage)
        throw e
      }
    }
  }

Scala version : 2.9.2
Java Version : 1.6
Using jtds 1.3.0
Output of java -version:

java version "1.6.0_35"
Java(TM) SE Runtime Environment (build 1.6.0_35-b10-428-11M3811)
Java HotSpot(TM) 64-Bit Server VM (build 20.10-b01-428, mixed mode)

Best Answer

Yes, your Java runtime is too old, according to Java class file format:

J2SE 7 = 51 (0x33 hex),
J2SE 6.0 = 50 (0x32 hex),
J2SE 5.0 = 49 (0x31 hex),
JDK 1.4 = 48 (0x30 hex),
JDK 1.3 = 47 (0x2F hex),
JDK 1.2 = 46 (0x2E hex),
JDK 1.1 = 45 (0x2D hex).

51.0 means you need Java 7 to run some of the classes in your project. And you are right it's jTDS that's causing the problem (from jTDS JDBC Driver 1.2.7 and 1.3.0 released):

Version 1.3.0 is the first Java 7 compatible version of the driver and

Either upgrade to Java 7 (always a good idea) or downgrade to some older jTDS driver.

Related Solutions

Java – How to create an executable JAR with dependencies using Maven

<build>
  <plugins>
    <plugin>
      <artifactId>maven-assembly-plugin</artifactId>
      <configuration>
        <archive>
          <manifest>
            <mainClass>fully.qualified.MainClass</mainClass>
          </manifest>
        </archive>
        <descriptorRefs>
          <descriptorRef>jar-with-dependencies</descriptorRef>
        </descriptorRefs>
      </configuration>
    </plugin>
  </plugins>
</build>

and you run it with

mvn clean compile assembly:single

Compile goal should be added before assembly:single or otherwise the code on your own project is not included.

See more details in comments.

Commonly this goal is tied to a build phase to execute automatically. This ensures the JAR is built when executing mvn install or performing a deployment/release.

<plugin>
  <artifactId>maven-assembly-plugin</artifactId>
  <configuration>
    <archive>
      <manifest>
        <mainClass>fully.qualified.MainClass</mainClass>
      </manifest>
    </archive>
    <descriptorRefs>
      <descriptorRef>jar-with-dependencies</descriptorRef>
    </descriptorRefs>
  </configuration>
  <executions>
    <execution>
      <id>make-assembly</id> <!-- this is used for inheritance merges -->
      <phase>package</phase> <!-- bind to the packaging phase -->
      <goals>
        <goal>single</goal>
      </goals>
    </execution>
  </executions>
</plugin>

Java – How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version

The version number shown describes the version of the JRE the class file is compatible with.

The reported major numbers are:

Java SE 17 = 61,
Java SE 16 = 60, 
Java SE 15 = 59,
Java SE 14 = 58,
Java SE 13 = 57,
Java SE 12 = 56,
Java SE 11 = 55,
Java SE 10 = 54,
Java SE 9 = 53,
Java SE 8 = 52,
Java SE 7 = 51,
Java SE 6.0 = 50,
Java SE 5.0 = 49,
JDK 1.4 = 48,
JDK 1.3 = 47,
JDK 1.2 = 46,
JDK 1.1 = 45

(Source: Wikipedia)

To fix the actual problem you should try to either run the Java code with a newer version of Java JRE or specify the target parameter to the Java compiler to instruct the compiler to create code compatible with earlier Java versions.

For example, in order to generate class files compatible with Java 1.4, use the following command line:

javac -target 1.4 HelloWorld.java

With newer versions of the Java compiler you are likely to get a warning about the bootstrap class path not being set. More information about this error is available in a blog post New javac warning for setting an older source without bootclasspath.

Best Answer

Related Solutions

Java – How to create an executable JAR with dependencies using Maven

Java – How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version

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