using getclass on references

[ronnir paterl]

Hi,

Im facing this wierd problem while using getClass method on different references

e.g
intarray.getClass() gives me "Class [I"
where intarray is a reference to int[]
Objarray.getClass() gives me "Class [Ljava.lang.Object;"
where Objarray is a reference to Object[] .. also why does it have ";" in the end
myclass.getClass() gives me "Class [Lmyclass;"
where myclass is a class created by me.

My Question are
a. Why doesnt it show the entire name of the class in eg. 1
b. What determines the prefix appended to the class names as in eg. 2 &3

Thanks

[Henry Wong]

My Question are
a. Why doesnt it show the entire name of the class in eg. 1
b. What determines the prefix appended to the class names as in eg. 2 &3

When you call the getClass() method, you will get a Class object that gives you a ton of information about the class -- its fields, its methods, its interfaces, etc.

To answer (a), one of the methods of the Class object that is returned, gives you the "entire name of the class".

To answer (b), I am assuming that you simply did a system out of the class object and got a string (that is pretty useless). When you print the Class object, all you see is the result of the toString() method. The result of the toString() method simple returns "Class" followed by the class descriptor (as a string) for the class.

Don't just println() the class object, use the methods of the class object to obtain the information about the class.

Henry

[Henry Wong]

.. also why does it have ";" in the end

BTW, for the full details on why it ends with ";", or start with "[L", etc., google for "Java class descriptor" -- for the string format of the descriptor.

Henry

[Ilja Preuss]

a) this is an array of *primitives* - there really isn't a true class name in this case.

[Rob Spoor]

Originally posted by Henry Wong:
To answer (b), I am assuming that you simply did a system out of the class object and got a string (that is pretty useless). When you print the Class object, all you see is the result of the toString() method. The result of the toString() method simple returns "Class" followed by the class descriptor (as a string) for the class.

Except he's not printing an instance of his own class, he's print an instance of an array of his own class.

Sadly, arrays have a quite useless toString() implementation. Instead, use the static Arrays.toString methods. That will print arrays just like the default collection implementations are printed.