Creating Objects in java

An Object in Java is a block of memory that contains space to store all the instance variables.  Creating an object of a class is a two-step process.

1.      Declare a variable of the class type.  At this stage, the variable refers to an object only.

2.      Assigning an actual, physical copy of the object and assign it to that variable by means of ‘new’ operator.  The new operator dynamically allocates memory for an object and returns a reference to that object.

            Example:         Rectangle rect1;                     // reference

                                    rect1 = new Rectangle();       // instantiate

                                                      (or)

                                    Rectangle rect1 = new Rectangle();

            The first statement declares a variable to hold the object reference.

	null

 

                                                                 rect1

            The second statement assigns the object reference and allocates memory

	Rectangle object

 

                       

                   rect1

Note: Each object contains its own instance variables of its class.  This means that any changes to the variables of one object have no effect on the variables of another.  But the function name is name for both objects.

            It is also possible to create two or more references to the same object.

            Example:         Rectangle r1 = new Rectangle( );

                                    Rectangle r2 = r1;

                       

Rectangle object

                        r1

 

                        r2