All geek questions in one place

Finding a .class file has a bad version

What is the easiest way to determine which Java class is compiled with the “wrong” version number?

I have a project with a lot of dependencies, and I have a class compiled using Java 1.6 where Java 1.5 is required. At runtime, I get an uninformative exception:

[WARN] StandardWrapperValve [shell]: Servlet.service () for servlet shell threw exception
java.lang.UnsupportedClassVersionError: Bad version number in .class file
    at java.lang.ClassLoader.defineClass1 (Native Method)
    at java.lang.ClassLoader.defineClass (ClassLoader.java:675)
    at java.security.SecureClassLoader.defineClass (SecureClassLoader.java:124)
    at java.net.URLClassLoader.defineClass (URLClassLoader.java:260)
    at java.net.URLClassLoader.access $ 100 (URLClassLoader.java:56)
    at java.net.URLClassLoader $ 1.run (URLClassLoader.java:195)
    at java.security.AccessController.doPrivileged (Native Method)
    at java.net.URLClassLoader.findClass (URLClassLoader.java:188)
    at java.lang.ClassLoader.loadClass (ClassLoader.java data16)
    at sun.misc.Launcher $ AppClassLoader.loadClass (Launcher.java:280)
    at java.lang.ClassLoader.loadClass (ClassLoader.java:251)
    at java.lang.ClassLoader.loadClassInternal (ClassLoader.javahaps74)
    at foo.Listener. (Listener.java:30)
    at foo.rpc.service.MapServiceImpl. (MapServiceImpl.java:58)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0 (Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance (NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance (DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance (Constructor.java:494)
    at java.lang.Class.newInstance0 (Class.javahaps50)
    at java.lang.Class.newInstance (Class.java:303)
    at com.google.gwt.dev.shell.GWTShellServlet.tryGetOrLoadServlet (GWTShellServlet.java:934)
    at com.google.gwt.dev.shell.GWTShellServlet.service (GWTShellServlet.java:276)
    at javax.servlet.http.HttpServlet.service (HttpServlet.java:717)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter (ApplicationFilterChain.java:237)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter (ApplicationFilterChain.java:157)
    at org.apache.catalina.core.StandardWrapperValve.invoke (StandardWrapperValve.java:214)
    at org.apache.catalina.core.StandardValveContext.invokeNext (StandardValveContext.java:104)
    at org.apache.catalina.core.StandardPipeline.invoke (StandardPipeline.java∗20)
    at org.apache.catalina.core.StandardContextValve.invokeInternal (StandardContextValve.java:198)
    at org.apache.catalina.core.StandardContextValve.invoke (StandardContextValve.java:152)
    at org.apache.catalina.core.StandardValveContext.invokeNext (StandardValveContext.java:104)
    at org.apache.catalina.core.StandardPipeline.invoke (StandardPipeline.java∗20)
    at org.apache.catalina.core.StandardHostValve.invoke (StandardHostValve.java:137)
    at org.apache.catalina.core.StandardValveContext.invokeNext (StandardValveContext.java:104)
    at org.apache.catalina.valves.ErrorReportValve.invoke (ErrorReportValve.java:118)
    at org.apache.catalina.core.StandardValveContext.invokeNext (StandardValveContext.java:102)
    at org.apache.catalina.core.StandardPipeline.invoke (StandardPipeline.java∗20)
    at org.apache.catalina.core.StandardEngineValve.invoke (StandardEngineValve.java:109)
    at org.apache.catalina.core.StandardValveContext.invokeNext (StandardValveContext.java:104)
    at org.apache.catalina.core.StandardPipeline.invoke (StandardPipeline.java∗20)
    at org.apache.catalina.core.ContainerBase.invoke (ContainerBase.java:929)
    at org.apache.coyote.tomcat5.CoyoteAdapter.service (CoyoteAdapter.java:160)
    at org.apache.coyote.http11.Http11Processor.process (Http11Processor.java:799)
    at org.apache.coyote.http11.Http11Protocol $ Http11ConnectionHandler.processConnection (Http11Protocol.java:705)
    at org.apache.tomcat.util.net.TcpWorkerThread.runIt (PoolTcpEndpoint.java=77)
    at org.apache.tomcat.util.threads.ThreadPool $ ControlRunnable.run (ThreadPool.java:683)
    at java.lang.Thread.run (Thread.java:613)

The only thing I see is the class foo.Listener, which requires all my dependencies (Camel, ActiveMQ, various in home libraries).

, , - opennoop , "how-can-i-find-the- -Java---- " . ?

+3
4

, UnsupportedClassVersionError. (Run → Java Eclipse)

, defineClass loadClass, .

+4

-verbose .

+1

( .jar ), , - (BCEL ASM)

0

In addition to what @gibbss said, you can use this command on the command line.

javap -v path-to-your-class-file > output.txt

After that, open the output.txt file with any editor. Information about the java version used to compile this class will appear at the beginning of the file. The information you should be looking for is the "java core version".
Use the information below to find out the version of java as soon as you learn the basic information.

Java 1.2 uses major version 46
Java 1.3 uses major version 47
Java 1.4 uses major version 48
Java 5 uses major version 49
Java 6 uses major version 50
Java 7 uses major version 51
Java 8 uses major version 52
0
source

Source: https://habr.com/ru/post/1710495/

More articles:


All Articles