A class can be defined as a template/blueprint that describes the behaviour/state that the object of its type support.
public class Dog { String breed; int age; String color; void barking() { } void hungry() { } void sleeping() { } }
Objects have states and behaviours. Example: A dog has states - colour, name, breed as well as behaviours – wagging the tail, barking, eating. An object is an instance of a class.
An object is created from a class. In Java, the new keyword is used to create new objects.
There are three steps when creating an object from a class −
Declaration − A variable declaration with a variable name with an object type.
Instantiation − The 'new' keyword is used to create the object.
Initialization − The 'new' keyword is followed by a call to a constructor. This call initializes the new object.
Following is an example of creating an object −
public class Puppy { public Puppy(String name) { // This constructor has one parameter, name. System.out.println("Passed Name is :" + name ); } public static void main(String []args) { // Following statement would create an object myPuppy Puppy myPuppy = new Puppy( "tommy" ); } }
Passed Name is :tommy