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I show you now a class in Java which has no public constructor!

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Are you sure that know Java well? Is it possible that class in Java has no public constructor? I do not mean default constructor with no arguments, which always exists, but its declaration can be skipped if it just one default constructor there...

No I mean no public constructor at all... And if so, why it is private? How it is supposed to be used if it is private? Is not it strange? If you can not instantiate a class, how you can use it?

Answer: it is class Class which has no public constructor Smile You are not supposed to construct it.

Instead Class objects are constructed automatically by the Java Virtual Machine as classes are loaded and by calls to the defineClass method in the class loader.

The following example uses a Class object to print the class name of an object:

 

void printClassName(Object obj) {
   System.out.println("The class of " + obj +
       " is " + obj.getClass().getName());
}
 

It is also possible to get the Class object for a named type (or for void) using a class literal (JLS Section 15.8.2). For example:

System.out.println("The name of class Foo is: "+Foo.class.getName());
 
Reference: Java API

 


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