static keyword in java

In Java, the static keyword is used to create variables and methods that are associated with a class rather than with individual objects of the class. This means that static variables and methods can be accessed without creating an object of the class, using the class name instead.

Here’s an example of a static variable:

public class Person {
    private String name;
    private static int count = 0;

    public Person(String name) {
        this.name = name;
        count++;
    }

    public String getName() {
        return name;
    }

    public static int getCount() {
        return count;
    }
}

public class Main {
    public static void main(String[] args) {
        Person person1 = new Person("John");
        Person person2 = new Person("Mary");
        Person person3 = new Person("Bob");

        System.out.println(Person.getCount()); // output: 3
    }
}

In this example, we have defined a Person class with a static variable called count, which keeps track of the number of Person objects that have been created. We have also defined a static method called getCount, which returns the value of the count variable.

In the Person constructor, we increment the count variable every time a new Person object is created. In the Main class, we create three Person objects and then use the getCount method to retrieve the value of the count variable.

static methods can also be used to perform operations that are not specific to individual objects of the class. Here’s an example:

public class MathUtils {
    public static int factorial(int n) {
        if (n == 0) {
            return 1;
        } else {
            return n * factorial(n - 1);
        }
    }
}

public class Main {
    public static void main(String[] args) {
        int result = MathUtils.factorial(5);
        System.out.println(result); // output: 120
    }
}

In this example, we have defined a MathUtils class with a static method called factorial, which calculates the factorial of a given integer. We can call this method using the class name and the dot operator, without creating an object of the MathUtils class.

In summary, the static keyword is used in Java to create variables and methods that are associated with a class rather than with individual objects of the class. static variables and methods can be accessed using the class name instead of an object reference.