Issue populating map in Groovy - groovy

Question

I've got an interesting issue in groovy, I am trying to populate a map and for some reason it doesn't work, here is the program (just made a bare-bones version to see the problem easier):
public class dd2 {
Map<String, String> subscriptions = ["Listing":"a Listing","Issue":"an Issue"]
Map<String, Object> subscriptionAttributes = new HashMap<String, Object>()
public static void main(String[] args) throws Exception {
def dd = new dd2()
dd.getSubscriptionAttributes()
}
def getSubscriptionAttributes(){
subscriptions.each {
def attributes = ""
println "getting ${it.key}"
subscriptionAttributes.put(it.key, attributes)
}
}
}
if I remove:
subscriptionAttributes.put(it.key, attributes)
it iterates through the whole map of subscriptions. If I try to add to the subscriptionAttributes map it will only get Listing until eventually I get stack overflow.
What am I doing wrong?

Answer 1

It's due to def getSubscriptionAttributes() method name - when getter method is defined Groovy uses it wherever you use a property name. So in your case you are getting:
*** java.lang.instrument ASSERTION FAILED ***: "!errorOutstanding" with message transform method call failed at JPLISAgent.c line: 844
*** java.lang.instrument ASSERTION FAILED ***: "!errorOutstanding" with message transform method call failed at JPLISAgent.c line: 844
*** java.lang.instrument ASSERTION FAILED ***: "!errorOutstanding" with message transform method call failed at JPLISAgent.c line: 844
Exception in thread "main" java.lang.StackOverflowError
at sun.net.www.protocol.file.Handler.parseURL(Handler.java:67)
at java.net.URL.<init>(URL.java:622)
at java.net.URL.<init>(URL.java:490)
at sun.misc.URLClassPath$FileLoader.getResource(URLClassPath.java:1259)
at sun.misc.URLClassPath.getResource(URLClassPath.java:239)
at java.net.URLClassLoader$1.run(URLClassLoader.java:365)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:361)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at groovy.lang.Closure.call(Closure.java:416)
at groovy.lang.Closure.call(Closure.java:430)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.callClosureForMapEntry(DefaultGroovyMethods.java:5278)
at org.codehaus.groovy.runtime.DefaultGroovyMethods.each(DefaultGroovyMethods.java:2117)
at org.codehaus.groovy.runtime.dgm$164.invoke(Unknown Source)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoMetaMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:274)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:56)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)
at dd2.getSubscriptionAttributes(dd2.groovy:13)
at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
at groovy.lang.MetaClassImpl.getProperty(MetaClassImpl.java:1850)
at groovy.lang.MetaClassImpl.getProperty(MetaClassImpl.java:3758)
at dd2.getProperty(dd2.groovy)
at org.codehaus.groovy.runtime.InvokerHelper.getProperty(InvokerHelper.java:174)
at groovy.lang.Closure.getPropertyTryThese(Closure.java:312)
at groovy.lang.Closure.getPropertyOwnerFirst(Closure.java:306)
at groovy.lang.Closure.getProperty(Closure.java:295)
at org.codehaus.groovy.runtime.callsite.PogoGetPropertySite.getProperty(PogoGetPropertySite.java:50)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callGroovyObjectGetProperty(AbstractCallSite.java:307)
at dd2$_getSubscriptionAttributes_closure1.doCall(dd2.groovy:16)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:93)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:325)
at org.codehaus.groovy.runtime.metaclass.ClosureMetaClass.invokeMethod(ClosureMetaClass.java:294)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1022)
at groovy.lang.Closure.call(Closure.java:414)
at groovy.lang.Closure.call(Closure.java:430)
because when you say:
subscriptionAttributes.put(it.key, attributes)
Groovy actually tries doing:
getSubscriptionAttributes().put(it.key, attributes)
and you get into infinite loop.
Change your method name so it does not conflict with internal map variable and you're good.