What is Method In Java

As we know Object is an entity with states and behavior , in java we are creating methods to represent behavior of object.

Method is defined as group of instructions grouped together to perform a task, one of the biggest advantage of method is re-usability.we can create a method in java and we can call that method many times to perform some task.We do not need to write same code again and again.We can execute a method by calling or invoking it.

One of the most important method in java is the main method ,execution of every java program , starts with main method :

How to write main method in java ?

	public static void main(String[] args) {
		
	}

Note - execution of every java program starts with main method.

- we can create our own method to perform some set of operations :

Method Signature In Java :

syntax :

AccessSpecifier ReturnType methodName(parameter1,parameter2){

}

NOTE - Method Name should be in Camel Case Format :

Example : addNumbers(),calculateInterest(),addition(), getEmployeeInformation() etc.

there are two main types of methods :

1.Predefined method.

2.User defined method.

1.Predefined methods are declared as part of java library , these are built in methods in java , which we can use as per requirement .Examples : toUpperCase(),toString(),length(),equals() etc.

2.User defined methods are created by programmer to perform some task.

Example of user defined method in Java :

	public int addTwoNumbers(int num1,int num2) {			
		return num1+num2;
	}	

method can be static or non-static , if method is available in another class we can call static method by using class name and we can call non-static method by using object of class.

Example of Method in same class in Java : 

now here our static method is available in same class ,so we can call it directly inside main method as in below, if method is not returning anything then we can use void as return type.

Example :

 public class MethodDemo {
    public static void main(String[] args) {
	addTwoNumbers(2,3);
    }		
    public static void addTwoNumbers(int num1,int num2) {
        System.out.println("Addition is :"+(num1+num2));
    }
   }

Output of above program :

Addition is :5

In above example both methods are static and are in same class, so we can easily call one static method in another directly. but what if addTwoNumbers() method is not-static ? we can call it using object , check below example : Example :

	
 public class MethodDemo {
    public static void main(String[] args) {
	 MethodDemo m1=new MethodDemo();
	 m1.addTwoNumbers(2,3);
    }
    public void addTwoNumbers(int num1,int num2) {
	System.out.println("Addition is :"+(num1+num2));
    }
 }
    

Output of above program is : Addition is :5 Note - if non-static method is available in another class , you can call method by creating object of that class. if static method is available in another class , you can call it directly by using class name. Example :

 public class CollegeApp {
	public static void main(String[] args) {
    	    Exam ex=new Exam();
     	    ex.doExamRegistration();
	    Exam.calculatePercentage();
	}	
 }	
 class Exam{
   public void doExamRegistration() {
	System.out.println("Enrolled for Exam");
   }	
   public static void calculatePercentage() {
	System.out.println("Percentage calculated");
   }
  }

Output is :
Enrolled for Exam 

Percentage calculated

Note : In above example in Exam class calculatePercentage is the static method , so we called it using class name, and doExamRegistration is non-static so we called it using object of class.