• Skip to main content
  • Skip to primary sidebar
  • Skip to secondary sidebar
  • Skip to footer

Computer Notes

Library
    • Computer Fundamental
    • Computer Memory
    • DBMS Tutorial
    • Operating System
    • Computer Networking
    • C Programming
    • C++ Programming
    • Java Programming
    • C# Programming
    • SQL Tutorial
    • Management Tutorial
    • Computer Graphics
    • Compiler Design
    • Style Sheet
    • JavaScript Tutorial
    • Html Tutorial
    • Wordpress Tutorial
    • Python Tutorial
    • PHP Tutorial
    • JSP Tutorial
    • AngularJS Tutorial
    • Data Structures
    • E Commerce Tutorial
    • Visual Basic
    • Structs2 Tutorial
    • Digital Electronics
    • Internet Terms
    • Servlet Tutorial
    • Software Engineering
    • Interviews Questions
    • Basic Terms
    • Troubleshooting
Menu

Header Right

Home » Java » Java Methods

Class variables and methods in Java

By Dinesh Thakur

To create a class variable or method, include the word static in front of the method’s name. The modifier static typically comes after any protection modifiers. Given below is an example that illustrates how a class variable may be created in a program. [Read more…] about Class variables and methods in Java

accessor methods in Java

By Dinesh Thakur

Accessor methods are used for initializing and accessing the value of instance variables. The value of these instance variables can be used further in the program. For creating accessor methods, it is required to create two methods among which one method is used to initialize the value and other is used to retrieve the value. An accessor method makes the program more readable and understandable. Moreover, accessor methods are similar to any other method, as can be seen from Program.

Implementing accessor methods.

// A program to find area of a square.

 

import java.io.*;

class AccessorMethodClass

{

         int side;

         //This method is used for initializing the value of global variable ‘side’

         public void setSideValue(int a)

        {

                 side = a;

        }

// This method is used for getting the value of the global value

     public int getSideValue()

     {

               return side:

      }

      public static void main(String args[ ])

     {

                       int area, side;

                     accessorMethodClass ob=new accessorMethodClass();

                     ob.setSideValue(10); // Initializing the value of global variable

                     side = ob.getSideValue(}; // Retrieving the value of Global variable

                     area = side * side; // Finding the area of square.

                     System.out.println(“The area of Square is” +area);

     }

}

The output of Program is as shown below:

The area of Square is 100

In Program the global variable side is initialized by the method setSideValue(int a) and its value is retrieved by the method getSideValue(). Here, the words like set and get make the functionality of accessor methods more clear even though it is not a part of any rules or specifications.

Accessor methods can also have names similar to their instance variable and Java performs the appropriate operation based on the use of these methods and variables, as shown in Program.

Using accessor methods II.

 

// A program to find the area of a square which is equal to square of the side.

import java.io.*;

class AccessorMethodClass

{

       int side;

      // Note that method name and variable name is same

      public void side(int a)

      {

             side = a;

      }

      public int getSideValue()

      {

                    return side;

       }

        public static void main(String args[])

       {

            int area, sidevalue;

               AccessorMethodClass ob = new AccessorMethodClass();

               ob.side(10);

               sidevalue = ob.getSideValue{);

            area = sidevalue*sidevalue;

               System.out.println(“The area of Square is”+area);

         }

}

The output of Program is as shown below:

The area of Square is 100

There are some problems with the convention used for having same name as described in the above program.

• Using same name for the instance variable and method may make the program less readable and understandable. Providing meaningful names to the variables and methods with respect to their functionality is a good programming practice.

• Adopting this type of convention violates the essentials of structured programming.

What is Methods in Java ? – Definition (With Examples)

By Dinesh Thakur

A Java method is a collection of statements, all performing a particular operation.  Let’s say that you were calling the method called System.out.println(); Java executes some different statements that print a message to your console.  We’re going to look at the creation of methods or, as they often called, functions. [Read more…] about What is Methods in Java ? – Definition (With Examples)

Example of Super Method in Java

By Dinesh Thakur

[Read more…] about Example of Super Method in Java

Static Method and Static Variable in Java Example

By Dinesh Thakur

Since the string variable str is static, it is initialized to “This is second line displayed” (static variables are initialized before an object is initiated). Then, the static block is executed which will invoke the disp() method displaying the message: “This is first line displayed”. Static() method can be invoked without the need of any object. In main(), again disp() method is called with the string str (This is second line displayed). After that an object SMV is made, and it will get a member str2 initialized to “This is last line displayed”. Then disp() is called with SMV. str2 which displays: This is last line displayed on the screen [Read more…] about Static Method and Static Variable in Java Example

Tail Recursion in java

By Dinesh Thakur

Tail recursion occurring when the recursive call is at the end of the recursive instruction. This eliminates the potential problem of stack overflow. A call is tail recursive if nothing has to be done after the call returns. i.e. when the call returns, the returned value is immediately returned from the calling method.

 

Greatest Common Divisor Using Recursion Java Example

By Dinesh Thakur

[Read more…] about Greatest Common Divisor Using Recursion Java Example

Reverse the Digits of a Number Using Recursion | Java Example

By Dinesh Thakur

In this program, user is asked a number to enter which is stored in integer form in variable n. The value entered is say 1023.Now, this value of variable n is passed to parameter x by invoking revers() method. In revers() method, x is divided by 10 and the remainder is displayed (% returns remainder). When 1023 is divided by 10, the remainder will be 3 which is displayed on the screen. Then, again revers() is invoked with value 102/10 i.e. with 102 (because the output of dividing two integers is also an integer). 102 is assigned to variable x. Again, 102 is divided by 10 and the remainder is displayed. The remainder this time will be 2 which is displayed. Again revers() method is invoked with 10/10 i.e. which 1. And the process continues until value of x becomes 0.

Here is the Java Example for ReverseDigits:

import java.io.*; 
class ReverseDigits
{
            void revers(int x)
            {
                        if(x==0) return;
                        else
                        {
                                    System.out.print(x%10);
                                    revers(x/10);
                        }
            }
            public static void main(String args[])
            throws IOException
            {
                        ReverseDigits Digit = new ReverseDigits();
                        BufferedReader bf=new BufferedReader(new InputStreamReader(System.in));
                        String h;
                        int n;
                        System.out.print("Enter a number to Reverse : ");
                        h=bf.readLine();
                        n=Integer.parseInt(h);
                        System.out.print("The  Reverse Number is : ");
                        Digit.revers(n);
            }
}

Reverse the Digits of a Number Using Recursion

Recursion in Java with Example

By Dinesh Thakur

Recursion occurs when a function calls itself in its own body. That is, in the body of the function definition there is a call to itself. When the function calls itself in its body, it results in an infinite loop. So, there has to be an exit condition in every recursive program.

The case in which the recursion ends is called a base case. In every recursive program, the problem is broken into small pieces so as to bring it closer to the base case.

Methods/Functions have locally defined variables (or objects) which have no existence outside the function. Each time a function is invoked recursively, a new set of variables (or objects) are created. Although they have the same names, their values are preserved till the end of the recursion. So, to implement recursion, the language has to take the help of stack to keep track of objects and statements of each recursive call.

Demonstrating the Concept of Recursion

class ConceptofRecursion 
{
            void display(int x,int y)
            {
                        if(x<1) return;
                        System.out.println("Value of x : "+ x );
                        display(x-1,y+1);
                        System.out.println("Value of y :"+y);
            }
            public static void main(String args[])
            {
                        ConceptofRecursion Recursion = new ConceptofRecursion();
                        Recursion.display(5,1);
            }
}

 

Recursion in Java

As, we can see in the above program, that the method display () is invoked with two arguments 5 and 1 which will be assigned to parameters x and y respectively. In display ()  method, value of x is displayed which prints following message on the screen : Value of x: 5

Then again display ()  is invoked with values 4 and 2 (because value of x is decremented and value of y is incremented by 1 while invoking the display (). But because of the recursive call, one statement of the program couldn’t execute, that statement is:

System.out.println(“Value of y :”+y);

So, the message: Value of y : 1 is pushed on to the stack.

By the recursive call, the values 4 and 2 will be assigned to parameters x and y respectively. Here, value of x is displayed which prints following message on the screen:

Value of x: 4

Again, display ()   is invoked with values 3 and 3 (because value of x is decremented and value of y is incremented by 1 while invoking the display () . But again, because of the recursive call, the following statement couldn’t execute:

System.out.println(“Value of y :”+y);

So, the message: Value of y: 2 is pushed on to the stack (above the message Value of y : 1) and so on. Hence, 5 messages will be pushed onto the stack which couldn’t execute as shown:

Disadvantages of Recursion

 

1. The problem of stack overflow occurs in case of infinite recursion

 

2. Recursion can be slower to run than simple iteration.

 

3. The recursive version is usually less efficient because of having to push and pop values on and off the run-time stack, so iteration is quicker.

 

Advantages of Recursion

 

1. It is easier to code a recursive solution.

 

2. The recursive code is usually smaller, more concise, and more elegant.

 

3. There are some real time problems that are very difficult to solve without recursion.

Passing Arguments to a Method in Java Example

By Dinesh Thakur

There are two ways of passing arguments to a method (function/subroutine):

1. Call by Value

This method copies the value of an argument into the formal parameter of the method. Therefore, changes made to the parameter of the method are limited to that method only and there is no impact of changes on the argument. That is, when control returns back to the caller method, earlier values of the arguments will be seen.

2. Call by Reference

In this method, a reference to an argument (not the value of the argument) is passed to the parameter. Inside the method, this reference is used to access the actual argument specified in the call. This means that changes made to the parameter will affect the actual argument also. When the control returns back to the caller method, the changes made in the method can be seen in the arguments in the caller method too.

In Java, when we pass a simple type to a method, it is passed by value. When we create a variable of a class, we are only creating a reference to an object. Thus, when we pass this reference method, the parameter that receives it will refer to the same object as that referred by the argument. This means that objects are passed to methods by reference.

 

Demonstration of Pass by Reference

 

 

class Passby

{

            int a,b;

            void setdata(int x,  int  y)

            {

                        a  =  x;

                        b = y;

            }

            void display(Passby m)

            {

                        m.a =m.a+10;

                        m.b=m.b-5;

            }

}

class PassbyRef

{

            public static void main(String args[])

            {

                        Passby Ref =new Passby();

                        Ref.setdata(50,100);

                        System.out.println(“Before Function Call: a=” + Ref.a +” b= ” + Ref.b) ;

                        Ref.display(Ref);

                        System.out.println(“After Function Call: a=” + Ref.a +” b= ” + Ref.b) ;

            }

}

 

Output

 

Before Function Call: a = 50 b= 100

After Function Call: a = 60 b= 95

 

In above program, first an instance of class Passbyby name Ref is made. The value of its data members a and b are set to 50 and 100 respectively by invoking setdata() method. After that by invoking display (), the instance Ref itself is sent as argument to parameter m. Since, we know that objects are passed to methods by reference, any changes made in the data members of parameter m will also effect the argument Ref. In the display (), the value of data member a is incremented by 10 and the value of data member is decremented by 5. The same effects will be seen in the argument Ref when the control returns back to the main() method.

 

Demonstration of Pass by Value

 

 

class PassbyValue

{

            public static void main(String args[])

            {

                        int a =50, b=100;

                        System.out.println(“Before Function Call : a = ” +a+ ” b = “+b);

                        chng(a,b);

                        System.out.println(“After Function Call : a = ” +a+ ” b = “+b);

            }

            static void chng(int x, int y)

            {

                        x=x+10;

                        y=y-5;

            }

}

 

Output:

Before Function Call: a= 50 b= 100

After Function call: a= 50 b= 100

 

When we pass a simple type to a method, it is passed by value. So, any changes made to the data in the method are limited to that method only and the data retains its older values when returns back to the caller.

Primary Sidebar

Java Tutorials

Java Tutorials

  • Java - Home
  • Java - IDE
  • Java - Features
  • Java - History
  • Java - this Keyword
  • Java - Tokens
  • Java - Jump Statements
  • Java - Control Statements
  • Java - Literals
  • Java - Data Types
  • Java - Type Casting
  • Java - Constant
  • Java - Differences
  • Java - Keyword
  • Java - Static Keyword
  • Java - Variable Scope
  • Java - Identifiers
  • Java - Nested For Loop
  • Java - Vector
  • Java - Type Conversion Vs Casting
  • Java - Access Protection
  • Java - Implicit Type Conversion
  • Java - Type Casting
  • Java - Call by Value Vs Reference
  • Java - Collections
  • Java - Garbage Collection
  • Java - Scanner Class
  • Java - this Keyword
  • Java - Final Keyword
  • Java - Access Modifiers
  • Java - Design Patterns in Java

OOPS Concepts

  • Java - OOPS Concepts
  • Java - Characteristics of OOP
  • Java - OOPS Benefits
  • Java - Procedural Vs OOP's
  • Java - Polymorphism
  • Java - Encapsulation
  • Java - Multithreading
  • Java - Serialization

Java Operator & Types

  • Java - Operator
  • Java - Logical Operators
  • Java - Conditional Operator
  • Java - Assignment Operator
  • Java - Shift Operators
  • Java - Bitwise Complement Operator

Java Constructor & Types

  • Java - Constructor
  • Java - Copy Constructor
  • Java - String Constructors
  • Java - Parameterized Constructor

Java Array

  • Java - Array
  • Java - Accessing Array Elements
  • Java - ArrayList
  • Java - Passing Arrays to Methods
  • Java - Wrapper Class
  • Java - Singleton Class
  • Java - Access Specifiers
  • Java - Substring

Java Inheritance & Interfaces

  • Java - Inheritance
  • Java - Multilevel Inheritance
  • Java - Single Inheritance
  • Java - Abstract Class
  • Java - Abstraction
  • Java - Interfaces
  • Java - Extending Interfaces
  • Java - Method Overriding
  • Java - Method Overloading
  • Java - Super Keyword
  • Java - Multiple Inheritance

Exception Handling Tutorials

  • Java - Exception Handling
  • Java - Exception-Handling Advantages
  • Java - Final, Finally and Finalize

Data Structures

  • Java - Data Structures
  • Java - Bubble Sort

Advance Java

  • Java - Applet Life Cycle
  • Java - Applet Explaination
  • Java - Thread Model
  • Java - RMI Architecture
  • Java - Applet
  • Java - Swing Features
  • Java - Choice and list Control
  • Java - JFrame with Multiple JPanels
  • Java - Java Adapter Classes
  • Java - AWT Vs Swing
  • Java - Checkbox
  • Java - Byte Stream Classes
  • Java - Character Stream Classes
  • Java - Change Color of Applet
  • Java - Passing Parameters
  • Java - Html Applet Tag
  • Java - JComboBox
  • Java - CardLayout
  • Java - Keyboard Events
  • Java - Applet Run From CLI
  • Java - Applet Update Method
  • Java - Applet Display Methods
  • Java - Event Handling
  • Java - Scrollbar
  • Java - JFrame ContentPane Layout
  • Java - Class Rectangle
  • Java - Event Handling Model

Java programs

  • Java - Armstrong Number
  • Java - Program Structure
  • Java - Java Programs Types
  • Java - Font Class
  • Java - repaint()
  • Java - Thread Priority
  • Java - 1D Array
  • Java - 3x3 Matrix
  • Java - drawline()
  • Java - Prime Number Program
  • Java - Copy Data
  • Java - Calculate Area of Rectangle
  • Java - Strong Number Program
  • Java - Swap Elements of an Array
  • Java - Parameterized Constructor
  • Java - ActionListener
  • Java - Print Number
  • Java - Find Average Program
  • Java - Simple and Compound Interest
  • Java - Area of Rectangle
  • Java - Default Constructor Program
  • Java - Single Inheritance Program
  • Java - Array of Objects
  • Java - Passing 2D Array
  • Java - Compute the Bill
  • Java - BufferedReader Example
  • Java - Sum of First N Number
  • Java - Check Number
  • Java - Sum of Two 3x3 Matrices
  • Java - Calculate Circumference
  • Java - Perfect Number Program
  • Java - Factorial Program
  • Java - Reverse a String

Other Links

  • Java - PDF Version

Footer

Basic Course

  • Computer Fundamental
  • Computer Networking
  • Operating System
  • Database System
  • Computer Graphics
  • Management System
  • Software Engineering
  • Digital Electronics
  • Electronic Commerce
  • Compiler Design
  • Troubleshooting

Programming

  • Java Programming
  • Structured Query (SQL)
  • C Programming
  • C++ Programming
  • Visual Basic
  • Data Structures
  • Struts 2
  • Java Servlet
  • C# Programming
  • Basic Terms
  • Interviews

World Wide Web

  • Internet
  • Java Script
  • HTML Language
  • Cascading Style Sheet
  • Java Server Pages
  • Wordpress
  • PHP
  • Python Tutorial
  • AngularJS
  • Troubleshooting

 About Us |  Contact Us |  FAQ

Dinesh Thakur is a Technology Columinist and founder of Computer Notes.

Copyright © 2025. All Rights Reserved.

APPLY FOR ONLINE JOB IN BIGGEST CRYPTO COMPANIES
APPLY NOW