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In fact, an enum type in Java is actually a special compiler-generated class rather than an arithmetic type, and enum values behave as global pre-generated instances of that class. Enum types can have instance methods and a constructor (the arguments of which can be specified separately for each enum value). All enum types implicitly extend the ...
Boxing is the operation of converting a value of a primitive type into a value of a corresponding reference type, which serves as a wrapper for this particular primitive type. Unboxing is the reverse operation of converting a value of a reference type (previously boxed) into a value of a corresponding primitive type. Neither operation requires ...
Integer are reference objects, on the surface no different from List, Object, and so forth. To convert from an int to an Integer, one had to "manually" instantiate the Integer object. As of J2SE 5.0, the compiler will accept the last line, and automatically transform it so that an Integer object is created to store the value 9. [2]
Primitive wrapper classes are not the same thing as primitive types. Whereas variables, for example, can be declared in Java as data types double, short, int, etc., the primitive wrapper classes create instantiated objects and methods that inherit but hide the primitive data types, not like variables that are assigned the data type values.
Push the value of field of object (or value type) obj, onto the stack. Object model instruction 0x7C ldflda <field> Push the address of field of object obj on the stack. Object model instruction 0xFE 0x06 ldftn <method> Push a pointer to a method referenced by method, on the stack. Base instruction 0x4D ldind.i
This is because the latter one is an instance call on the primitive value 42, while the former one is an instance call on an object of type java.lang.Integer. Finally, another difference is that Java makes heavy use of boxed types in generics (see below).
Another way is to make another class that extends java.lang.Enum<E>) and may therefore define constructors, fields, and methods as any other class. As of C++11 , C++ supports strongly-typed enumerations which provide more type-safety and explicit specification of the storage type.
Comparison of Java and .NET platforms ALGOL 58's influence on ALGOL 60; ALGOL 60: Comparisons with other languages; Comparison of ALGOL 68 and C++; ALGOL 68: Comparisons with other languages; Compatibility of C and C++; Comparison of Pascal and Borland Delphi; Comparison of Object Pascal and C; Comparison of Pascal and C; Comparison of Java and C++