Introduction to Class in Java

 In Java, a class is a blueprint or a template that defines the properties and behaviors of objects. It provides a way to encapsulate data and functionality into a single unit, making it easier to organize and manage code.

A class consists of fields, constructors, and methods. Fields are variables that hold data, while constructors are special methods that are used to create objects of the class. Methods are functions that perform actions or calculations on the data in the class.

Here is an example of a simple class in Java:

csharp
public class Person {
   private String name;
   private int age;

   public Person(String name, int age) {
      this.name = name;
      this.age = age;
   }

   public void sayHello() {
      System.out.println("Hello, my name is " + name);
   }

   public int getAge() {
      return age;
   }

   public void setAge(int age) {
      this.age = age;
   }
}

In this example, the Person class has two fields, name and age, a constructor that takes two arguments, and two methods, sayHello() and getAge(). The setAge() method allows us to modify the age of the person object after it has been created.

To use this class, we would create objects of the Person class by calling the constructor and passing in the required arguments, like so:

java
Person person1 = new Person("John", 30);

We can then call the methods of the person1 object, like person1.sayHello() or person1.getAge(), to perform various actions or retrieve information about the object.