how do I know if my code base has java 8 methods

[Katedral Pillon via StackOverflow]

I am having some problems where AppEngine is complaining that my code has Java 1.8 methods, whereas AppEngine requires Java 1.7. Here is the error trace. I am not sure how to fix it.

Failed startup of context com.google.apphosting.utils.jetty.RuntimeAppEngineWebAppContext@6c5c4442{/,/base/data/home/apps/s~myapi-mobile/1.123456789034567}
org.mortbay.util.MultiException[java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0, java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0]
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:656)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.createHandler(AppVersionHandlerMap.java:203)
    at com.google.apphosting.runtime.jetty.AppVersionHandlerMap.getHandler(AppVersionHandlerMap.java:176)
    at com.google.apphosting.runtime.jetty.JettyServletEngineAdapter.serviceRequest(JettyServletEngineAdapter.java:133)
    at com.google.apphosting.runtime.JavaRuntime$RequestRunnable.run(JavaRuntime.java:501)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
    at com.google.apphosting.runtime.ThreadGroupPool$PoolEntry.run(ThreadGroupPool.java:235)
    at java.lang.Thread.run(Thread.java:745)
java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0
    at com.google.appengine.runtime.Request.process-9f0a91645afbfd1f(Request.java)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:820)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:375)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
    at java.lang.Thread.run(Thread.java:745)
java.lang.UnsupportedClassVersionError: org/apache/jsp/editor_005fform_jsp : Unsupported major.minor version 52.0
    at com.google.appengine.runtime.Request.process-9f0a91645afbfd1f(Request.java)
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:820)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at sun.reflect.GeneratedMethodAccessor5.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:606)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:375)
    at org.mortbay.util.Loader.loadClass(Loader.java:91)
    at org.mortbay.util.Loader.loadClass(Loader.java:71)
    at org.mortbay.jetty.servlet.Holder.doStart(Holder.java:73)
    at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:242)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:685)
    at org.mortbay.jetty.servlet.Context.startContext(Context.java:140)
    at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1250)
    at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:517)
    at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:467)
    at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:50)
    at com.google.tracing.TraceContext$TraceContextRunnable.runInContext(TraceContext.java:446)
    at com.google.tracing.TraceContext$TraceContextRunnable$1.run(TraceContext.java:453)
    at com.google.tracing.CurrentContext.runInContext(CurrentContext.java:276)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContextNoUnref(TraceContext.java:312)
    at com.google.tracing.TraceContext$AbstractTraceContextCallback.runInInheritedContext(TraceContext.java:304)
    at com.google.tracing.TraceContext$TraceContextRunnable.run(TraceContext.java:450)
    at java.lang.Thread.run(Thread.java:745)

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http://stackoverflow.com/questions/40073992/how-do-i-know-if-my-code-base-has-java-8-methods

[Timothy Truckle via StackOverflow]

The message does not tell that you have Java8 methods, it tells that your Java files have been compiled using Java8 compiler whereas the execution environment is an earlier Java version.

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http://stackoverflow.com/questions/40073992/how-do-i-know-if-my-code-base-has-java-8-methods/40074037#40074037

[TroyS via StackOverflow]

To answer the actual question, you can attempt to compile your code using a Java 7 (or lower) compiler, and see what happens.

If the code compiles without issue, it's likely not using Java 8 methods (although that isn't necessary true, there could be Java 8 methods called using reflection).

If there are exceptions, you would have to inspect the exceptions to see their root cause.

If the errors report methods that don't obviously exist (e.g. the new collections/ streams API), or they report unrecognised syntax (e.g. using lambdas, () -> {}), then you are likely using Java 8.

Please DO NOT REPLY directly to this email but go to StackOverflow:

http://stackoverflow.com/questions/40073992/how-do-i-know-if-my-code-base-has-java-8-methods/40075436#40075436