I followed these directives perfectly and I get these errors when I compile: [javac] /home/jones/projects/COCFramework/src/it/unisa/dmi/l3p/COCFramework/DataModel/PersistentEnum.java:135: warning: non-varargs call of varargs method with inexact argument type for last parameter; [javac] cast to java.lang.Class for a varargs call [javac] cast to java.lang.Class[] for a non-varargs call and to suppress this warning [javac] Method mth = other.getClass().getMethod("getEnumCode", null); [javac] ^ [javac] /home/jones/projects/COCFramework/src/it/unisa/dmi/l3p/COCFramework/DataModel/PersistentEnum.java:136: warning: non-varargs call of varargs method with inexact argument type for last parameter; [javac] cast to java.lang.Object for a varargs call [javac] cast to java.lang.Object[] for a non-varargs call and to suppress this warning [javac] Serializable enumCode = (Serializable) mth.invoke(other, null); [javac] ^ [javac] /home/jones/projects/COCFramework/src/it/unisa/dmi/l3p/COCFramework/DataModel/PersistentIntegerEnum.java:87: compareTo(java.lang.Integer) in java.lang.Integer cannot be applied to (java.io.Serializable) [javac] return ((Integer) getEnumCode()).compareTo(((PersistentEnum) other).getEnumCode()); [javac] ^ [javac] Note: Some input files use unchecked or unsafe operations. [javac] Note: Recompile with -Xlint:unchecked for details. [javac] 1 error [javac] 2 warnings