Category Archive for: Introducing Classes

Instance Variable Hiding

Instance Variable Hiding As you know, it is illegal in Java to two local variables with the same name inside the same or enclosing scopes. interestingly, you can have local variables, including formal parameters to methods, which overlap with the names of the class’ instance variables. However, when a local variable has the same name as an…

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Parameterized Constructors

Parameter Constructors While the Box( ) constructor in the preceding example does initialize a Box object, it is . not very useful=-all boxes have the same dimensions. What is needed is a way to construct Box objects of various dimensions. The easy solution is to add parameters to the constructor. As you can this makes them much more…

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Constructors

Constructors It can be tedious to initialize all of the variables in a class each time an instance is created. Even when you add convenience functions like set Dim( ), it would be simpler and more concise to have all of the setup done at the time the object is first created .. Because the requirement for…

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Returning a Value

Returning a Value While the implementation of volume( ) does move the computation of a box’s volume inside the Box class where it  it is not the best way’ to do it. For example, what if another part of your program wanted to know the volume of a box, but not display its value? A better way to…

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Adding a Method to the Box Class

Adding a Method to the Box Class Although it is perfectly fine to create a class that contains only data, it rarely happens, Most of the time you will use methods to access the instance variables defined by the . . class. In fact, methods dcfir e the interface to most classes ..This allows the class implementor to…

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Assigning Object Reference Variable

Assigning Object Reference Variable Object reference variables act differently than you might expect when an assignment , takes place. For example, what do you think the following fragment docs?You might think that  is being assigned a reference to a copy of the object referred to by That is, you might think that  to separate and distinct objects. However,…

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A Closer Look at new

A Closer Look at new Here, class-var is a variable of the class type being created. The class name is the name of the class that is being instantiated. The class name followed by parentheses specifies the constructor for the class. A constructor defines what occurs when an object of a class is created. Constructors are an important…

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Declaring Objects

Declaring Objects As just explained, when you create a class. you are creating a new data type. You can use this type to declare objects of that type. However, obtaining objects of a class is a two-step process. First, you must declare a variable of the class type. This variable does not define an object. Instead,…

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A Simple Class

A Simple Class Let’s begin or study of the class with a simple example. Here is a ‘class called Box that defines three instance variables: width,  eight, and depth. Currently, Box docs not contain any methods (but some will be added soon).After this statement executes, my box will be an instance of Box. Thus, it will have…

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The Complete Reference

The Complete Reference The class is at the core of java.It is the logical construct upon which the entire Java language is built because it defines the shape and nature of an object. As such, the class forms the basis’ for object-oriented programming in Java. Any concept .you wish to implement in a Java program must be…

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