first class

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first class

A class is defined as follows:

	class name_of_class {
		instance variable(s);
		method(s);
	} //end of class

Write a class called circle which has three instance variables center( x,y ) and radius with two methods area and circumference.

You should have 3 constructor methods

Whenever an overloaded function is called, the function which matches the call is the one that is executed (Dynamic Method Lookup).

When methods are overriden, Java always invokes the right one.
Like virtual functions in C++.
Done with method lookup tables.
Lookup is the default, but final, private, and static methods are invoked directly without lookup. This can be more efficient.

Now, outside of the class, perhaps in a Main routine, you can create an object which is an instance of a class. To create a new object, you instantiate it. e.g.

        ClassName object_name  = new ClassName();

Now, still outside of the class, perhaps in a Main routine, to invoke a method of a class object, specify the object name, a dot ".", and then the method name. For example:

 object.method();

Implement the class in the main part. Create 3 objects and use all the methods.