Introduction to Object in Java
Java is a powerful object-oriented programming language that consists of objects and classes. The objects make it easier to map real-life entities while coding. The objects will be used all the time while programming in java. The objects in java are easy to define and use. It is necessary to understand Classes and Objects because everything in an object-oriented programming language like Java is based upon them.
How to Create an Object in Java?
- If you are familiar with Java programming, you may know that an object is created using a class in java. The class is nothing, but it provides a blueprint for creating an object. The class is used to instantiate an object. So technically, we will be having the class declared already before we create the object in Java.
Let’s see the syntax of creating an object:
ClassName objectName = new ClassName();
- The syntax is simple and easy to understand. It starts with the class name for which we are declaring an object, followed by the object name. The object name is nothing, but it is similar to declaring a variable name with the user-preferred name. Till this process of defining an object with a name is called as object declaration in Java.
- Object declaration is followed by an equal to (=) sign, which will assign the reference of the object to our declared object variable. The new keyword is used for creating the new object. This new keyword will create a new object using the blueprint, i.e. class, and will allocate memory for the object. This creation of a new object is called object instantiation in Java.
- The new keyword is then followed by the method or the constructor of the class. The new keyword will call the constructor automatically of the class while creating a new object; this process is known as object initialization in java.
We can also declare an object in a different way. First, we will declare it, and then we can initialize it.
ClassName objectName; // Declarationobject Name = new ClassName(); // Initialization
- Every time we create a new object in java, the memory will be allocated for the newly created object, and the reference of that object will be returned to the object variable. This object reference is then can be used to perform different actions related to an object. Object reference here is nothing but corresponds to the newly declared object variable name.
Characteristics of Object in Java
- Every object in java will have its own identity. No two objects will have the same identity. Every object will correspond to a different memory location, and the address of the memory location will not be available to the user.
- An object will have its type associated with it. Every object will have a data type as a class.
- An object will also have two things state and behavior declared in it. These things are declared in class itself. The state will define attributes, and behavior will define the actions related to the class.
Properties of Object in Java
When defining a class in Java, we define the main two things. The first represents the attribute or state. This is known as the properties of an object. The properties are nothing but the specific data which is related to the class. Every object, when created in java, it will have these properties available with it. We can access these properties in the class or outside by using the object reference depending upon the modifier used for it. As the object resembles a real-time entity, properties represent the state of an entity. For example, an object of Mobile may have a property like size, weight, etc. The different memory locations will be allocated for every property related to the object we create.
Methods of Object in Java
- The second main thing which we declare while creating a class is methods. These methods are nothing but are like the functions which are declared in a class. The methods are again specific to the class in which they are declared. The methods represent a specific action or process to be performed when called using the object reference. The methods are like behavior in the real world. For example, the mobile will perform the action of calling or dialing. Calling action is nothing but the behavior of the mobile.
- While programming in Java, we will normally create an object and assign values to its data members and perform specific actions related to it using the methods. The methods are an easy way to combine and perform the specific actions which are required while programming.
- We can perform anything which is the requirement in methods. The methods can also access the data members defined in the class. We can perform the actions on the data members in a class. We can define any number of methods in the class as long as required.
Rules for Object in Java
- There are no such hard rules for the declaration of any object, but we should follow the standard java naming convention while declaring the object name.
- We can access the methods of a class only by object reference or by class reference in special cases, but in any of both situations, we cannot access or modify the implementation of methods.
- We can reuse the once-defined object as many times as we want.
- We can easily remove or replace the object being used depending upon the requirement.
So, everything in java revolves around the object. An object can be created simply by using the class name. An object will contain state and behavior. We can access the methods and data members of the class using the object reference. Every object will have certain characteristics or properties related to it. Being an object-oriented programming language, everything in java is an object. The objects make the java programming language more secure and robust.
This is a guide to Object in Java. Here we discuss how to create an object in java, its characteristics, properties, methods, along with rules. You may also look at the following articles to learn more –