Objects are crucial to building complex and efficient Java applications.
When a developer creates a complex system, the process design begins, dividing the various project requirements into component applications. In the last phase, they are represented by objects in the application and are implemented in the code by class declarations. It might be difficult to see the benefits of this technique while learning (and working on small projects), but if you adopt the right techniques right now, you will develop the skills required for Java professional development.
Using Objects gives you the ability to share responsibility between different sections of an application. For example, you can implement certain requirements of your program using different methods by calling them from the main part of the code. Objects provide you with similar functionality, but you must remember that each object has its own class, defined in a separate .java file.
Objects that you may have already used (such as String, Array, etc.) also have their own class statements – these are predefined by Java language – and even if you can not access the code, you can see their properties and methods in Java API (Application Programming Interface). The objects you define yourself will work the same way.
Class properties:
The members or properties of a class are information that is stored in each instance of an object. If a class property has been declared private, it means that its value can only be changed from within that class.
Class builder.
You can see that it looks the same as any other method, except that the type of data returned is specified. Because the builder is only used to create a class object using the “new” keyword, what it returns is an instance of the class. This method initializes the property of the class with a value, which means it assigns a value to the helperNum variable. It is recommended that after the execution of the constructor, no property remains uninitialized, as this could generate a series of errors.
Public method.
The statement contains a public “getNumber” method, which can be called from anywhere, even from another class. Even though the example might seem trivial, it is normal to have methods that set or return values of class properties.
The importance of these methods is related to the fact that some properties of the class are private. A basic principle of object-oriented programming is the creation of a well-defined interface – this means that access to any data within a class is done through one of a method. If the class properties were public, an external code could have directly changed their value, which is not recommended because the external code would not pay attention to the implementation details of that class. If you restrict access to these properties, in a public method, you can do any checks to ensure that data received as parameters or returned are valid.
A class may have private methods that are only used inside it. For example, one of the public methods might involve a complex and repetitive process that you decide to define in a proprietary method called by the public method – in this case, your own, specific method should be declared private because you even the implementation of the class, to which the external code should not have access.
Principles of Objects.
If you do not know a lot about objects, it could help you see them as “black boxes.” One of the principles that make Java suitable for large project development is that any application developed in Java can be used as part of another application.
Because a separately developed component can be used in another application, its implementation details should not matter. As long as the component has a well-defined interface, you should be able to use the resources it provides without knowing anything about what’s happening inside – as you can use a String or Array without understanding how they are implemented in the code. In this case, you can consider the objects as “black boxes”, as the external code should let you use them without paying attention to how they are built.
As a final observation, you should know that a class can have several builders if each of them has different parameters. Creating an object will cause one of the builders to call on the parameters you send. If you do not define any constructor, Java will create one by default.