In Java, a class is a blueprint or template for creating objects. It defines a set of attributes and methods that are common to all objects of that class. An object is an instance of a class, which means that it is created from the blueprint defined by the class.
Here are some important points to keep in mind about classes in Java:
# A class is declared using the class keyword, followed by the name of the class.
# The body of the class is enclosed in curly braces {}.
# The attributes of the class are declared inside the class body, but outside of any method.
# The methods of the class are also declared inside the class body, but after the attributes.
# The public keyword is used to specify that a class, attribute, or method can be accessed from outside the class. If no access modifier is specified, the attribute or method is only accessible within the class.
Here is an example of a simple class in Java:
simple class declaration
public class Person {
public String name;
public int age;
public static void main(String args[]) {
System.out.println("Hello, my name is " + name + " and I am " + age + " years old.");
}
}
In this example, we have defined a class called Person with two attributes (name and age) and one method (sayHello). The sayHello method prints a message to the console that includes the person’s name and age.
To create an object of the Person class, we can use the following code:
creating an object
Person john = new Person();
john.name = "John";
john.age = 30;
john.sayHello();
This code creates a new Person object called john, sets the name and age attributes, and calls the sayHello method.
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