Learn How to Create Classes in Java
It’s not too difficult to learn how to create classes in Java. Whether you’re a beginner or an experienced developer, creating classes in Java is one of the fundamental building blocks in the development of Java applications.
A class is a blueprint of an object in Java, which defines its properties and behavior. It is an encapsulation of data members and member functions. In other words, classes are a way to define real-world objects that can be instantiated and used in your program.
Here are the steps to create a class in Java:
Step 1: Define the Class
To define a class, you will need to open a new file in your IDE (Integrated Development Environment) and give it a name. The name of the class file should match the name of the class.
For example, if you want to create a class called “Person,” then the file name should be “Person.java.”
Once you have created the file, you need to define the class using the “class” keyword followed by the name of the class. Here is an example:
public class Person {
// Class Definition
}
Step 2: Declare Variables
Once you have defined the class, you can declare variables that will be used to store data in the class. These variables are known as member variables or instance variables.
To declare a variable, you will need to specify its type (e.g. int, double, String) followed by its name. For example, to declare a variable called “age” of type int, you can write:
public class Person {
int age;
}
Step 3: Create Methods
After declaring the variables, you can create methods which will be used to perform operations on the data stored in the class.
To create a method, you need to define the return type of the method (e.g. void, int, String) followed by its name and any parameters that the method will accept. Here is an example:
public class Person {
int age;
void setAge(int newAge) {
age = newAge;
}
}
In this example, we are creating a method called “setAge” which accepts an integer parameter called “newAge.” The method then sets the value of the “age” variable to the value passed into the method.
Step 4: Create an Object
Once you have defined the class, declared variables, and created methods, you can create an object of the class.
To create an object, you need to use the “new” keyword followed by the name of the class and any arguments that the constructor of the class requires.
Here is an example:
public class Person {
int age;
void setAge(int newAge) {
age = newAge;
}
}
public class Main {
public static void main(String[] args) {
Person john = new Person();
john.setAge(25);
}
}
In this example, we are creating an object called “john” of class “Person.” We then call the “setAge” method on the “john” object passing the value 25 as an argument.