![]() And we can access the member variables and methods using both the objects.įinally we are assigning null to myBox2 and this causes the object to lose the reference of the allocated memory location. So, now myBox and myBox2 both point at the same allocated memory location. Then we are declaring another object myBox2 of the same class and then assigning the reference saved in myBox to myBox2. In the following example we are creating an object myBox of PackagingBox class. We can assign the reference saved in one object of a class to another object of the same class. calling the getPrice method to get the price In the following example we are accessing the public methods and public variables of the PackagingBox class using the myBox object. And this is only possible if the variables and methods are accessible from outside i.e. operator to access the member variables and call the methods of the class via object of the class. Accessing member variables and methods of a class via object ClassName objectName = new ClassName() Įxample: PackagingBox myBox = new PackagingBox() Īfter the object is created we can then access the member variables and call the methods of the class via the object. More on constructors in the next tutorial.Ĭombining all three steps. ![]() If no constructor is defined for the class then Java compiler adds a default constructor to the class. objectName = new ClassName() Īfter the class name we have the parenthesis () which calls the constructor of the class and initialises the object.Ĭonstructors are an important part of a class and most real world class will have a constructor explicitly defined. Note! In the object instantiation step we are writing the following code. In the following code we are instantiating an object of the PackagingBox class. Meaning, the object now points at the allocated space. The reference of the allocated memory space is then set to the object. In the object instantiation step we use the new keyword followed by the class name and this allocates the required memory space for the object. This creates myBox object and at this moment it is not pointing at any allocated memory location. In the following code we are declaring an object myBox of PackagingBox class. means that other Java classes (classes other than the Displayer class in Listing 3-1) can use the features declared in Listing 3-1. And we do this by writing the class name and then the object name. The first step is the declaration of the object. To understand this lets take the PackagingBox class we have been working on. To create an object we go through the following steps - Object declaration, Object instantiation and then Object initialisation. Using the class we can then instantiate an object of that class. When we create a class we create a new data type. Now, lets talk about object and how to create objects of a class.Ī class is a blueprint of an object. And we have been working on a class named PackagingBox. So far we have learned how to create a class then add some member variables and some methods. ![]() In this tutorial we will learn about class objects in Java programming language.
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