A method is a block of code, a group of statements, or a set of code that performs a specific task or operation. These are also known as functions in other programming languages.

• The method describes the behavior of an object.
• It increases code reusability.
• It also provides an easy modification of the code.

Method Declaration:

Method attributes such as visibility, return type, name, and arguments are all listed in the method declaration.

• A method signature can be found in every method. It’s included in the method definition. It contains the method name as well as a list of parameters.
• The method’s access specifier or modifier is the method’s access type. It specifies the method’s visibility. There are four different types of access specifiers in Java:

Modifier	Class	Package	Subclass	Global
Public	Yes	Yes	Yes	Yes
Protected	Yes	Yes	Yes	No
Default	Yes	Yes	No	No
Private	Yes	No	No	No

• The return type of a method is the data type it returns. It could be a primitive data type, an object, a collection, or void, for example. The void keyword is used when a method does not return anything.
• The name of a method is defined by its method name, which is a unique name. It must be appropriate for the method’s functionality.
• The parameter list is a collection of parameters separated by a comma and enclosed in parentheses.
• The method declaration includes the method body. It contains all the actions that must be completed. It is protected by a pair of curly braces.

  Syntax to declare the method in Java:

Access_specifier return-type methodName(parameter-list) //method header
{
 //method-body  method signature
}

Example:

public String getDetails(String st, int age, float per)
{
 String details=details+" "+st+" "+a+" "+per;
 return details;
}

Calling a Method:

In a program, calling a method is straightforward. The program control passes to the called method when we call or invoke a user-defined method.

for instance,

String ans=getDetails("Rabecca Fatima",20,89.70);

It will return a value Rabecca Fatima 20 89.70 after appending the argument passed during the method call.

Example: Even or Odd

import java.util.Scanner;  
public class EvenOdd  
{  
public static void main (String args[])  
{  
//creating Scanner class object     
Scanner sc=new Scanner(System.in);  
System.out.print("Enter the number: ");  
//reading value from user  
int num=sc.nextInt();  
//method calling  
findEvenOdd(num);  
}  
//user defined method  
public static void findEvenOdd(int num)  
{  
//method body  
if(num%2==0)   
System.out.println(num+" is even");   
else   
System.out.println(num+" is odd");  
}  
}  

Output:

By providing different inputs, we get different values accordingly.

Enter the number: 34
34 is even
Enter the number: 91
91 is odd

Types of Method

There are two types of methods in Java:

• Predefined Method
• User-defined Method

Predefined method:

• Predefined methods are methods that are already defined in the Java class libraries.
• It’s also known as the built-in method or standard library method. We can use these methods directly by calling them at any point in the program.
• length(), equals(), compareTo(), sqrt(), and other pre-defined methods are examples.

User-defined method:

• A user-defined method is a method created by the user or programmer.
• These methods are modified according to the requirement.
• The even-odd program is an example of the user-defined method.

call-by-reference and call-by-value

An argument can be passed to a method in two ways.

• call-by-value: In this approach, a method is passed a copy of an argument value. Inside the method, changes to the argument value have no effect on the arguments.
• call-by-reference: A method is called by passing a reference to an argument. The argument value will be affected by any changes made within the method.

Important: Java is Strictly Pass by Value

Note: also read about the OOPs in Java

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