Which Java version is supported by Spring Cloud?

Question

Under http://start.spring.io (Initializr) you can create a Spring Cloud application for Java 6. The Spring Boot reference documentation still gives the hint that Java 6 is supported: http://docs.spring.io/spring-boot/docs/1.2.2.RELEASE/reference/htmlsingle/#howto-use-java-6 I can compile the generated "Initializr" project with Java 6, but when I try to run the application on Java 6 I get the following UnsupportedClassVersionError:

java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:53)
    at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.IllegalArgumentException: Cannot instantiate interface org.springframework.context.ApplicationListener : org.springframework.cloud.bootstrap.BootstrapApplicationListener
    at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:381)
    at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:358)
    at org.springframework.boot.SpringApplication.initialize(SpringApplication.java:231)
    at org.springframework.boot.SpringApplication.<init>(SpringApplication.java:206)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:957)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:946)
    at com.daimler.daivb.services.common.configserver.ConfigserverApplication.main(ConfigserverApplication.java:16)
    ... 6 more
Caused by: java.lang.UnsupportedClassVersionError: org/springframework/cloud/bootstrap/BootstrapApplicationListener : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:631)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:615)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at org.springframework.boot.loader.LaunchedURLClassLoader.doLoadClass(LaunchedURLClassLoader.java:163)
    at org.springframework.boot.loader.LaunchedURLClassLoader.loadClass(LaunchedURLClassLoader.java:136)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    at org.springframework.util.ClassUtils.forName(ClassUtils.java:249)
    at org.springframework.boot.SpringApplication.getSpringFactoriesInstances(SpringApplication.java:374)
    ... 12 more

So the question is, is it a mistake that the spring-cloud-context-1.0.1.RELEASE.jar:/org/springframework/cloud/bootstrap/BootstrapApplicationListener.class library has been compiled with Java 7 and target version Java 7?

Answer 1

Spring Cloud requires Java 7 (except for one module that requires java 8). The Spring Cloud Commons readme will get updated with that information. I'll see about logging an issue with Initializr to not allow java 6 when spring cloud dependencies are chosen.