BeginnersBook

  • Home
  • Java
    • Java OOPs
    • Java Collections
    • Java Examples
  • C
    • C Examples
  • C++
    • C++ Examples
  • DBMS
  • Computer Network
  • Python
    • Python Examples
  • More…
    • jQuery
    • Kotlin
    • WordPress
    • SEO
    • JSON
    • JSP
    • JSTL
    • Servlet
    • MongoDB
    • XML
    • Perl

For loop in Java with example

Last Updated: September 11, 2022 by Chaitanya Singh | Filed Under: java

For loop is used to execute a set of statements repeatedly until a particular condition returns false. In Java we have three types of basic loops: for, while and do-while. In this tutorial you will learn about for loop in Java. You will also learn nested for loop, enhanced for loop and infinite for loop with examples.

Syntax of for loop:

for(initialization; condition ; increment/decrement)
{
   statement(s);
}

Initialization: In the initialization part, variables like loop counter (you will generally see i and j in loops, these are the loop counters) are initialized. This is an optional part of the loop as the variables can be initialized before the loop. This executes only once when the loop starts.

Condition: This is one of the important part of the loop. This condition determines till when the loop should keep repeating. The loop keeps repeating until the condition becomes false.

Increment/Decrement: In this part of the loop declaration, you can specify the increment or decrement of loop counter. This is to modify the loop counter value so that at one point condition becomes false and the loop ends.

Statement: The statements inside the loop body keeps executing for each iteration of the loop until the loop stops.

Flow of Execution of the for Loop

As a program executes, the interpreter always keeps track of which statement is about to be executed. We call this the control flow, or the flow of execution of the program.
for loop Java

First step: In for loop, initialization happens first and only one time, which means that the initialization part of for loop only executes once.

Second step: Condition in for loop is evaluated on each iteration, if the condition is true then the statements inside for loop body gets executed. Once the condition returns false, the statements in for loop does not execute and the control gets transferred to the next statement in the program after for loop.

Third step: After every execution of for loop’s body, the increment/decrement part of for loop executes that updates the loop counter.

Fourth step: After third step, the control jumps to second step and condition is re-evaluated.

Example: Simple for loop

This is a simple example of for loop. Here we are displaying the value of variable i inside the loop body. We are using decrement operator in the loop so the value of i decreases by one after each iteration of the loop and at some point the condition i>1 returns false, this is when the loop stops.

class ForLoopExample {
    public static void main(String args[]){
         for(int i=10; i>1; i--){
              System.out.println("The value of i is: "+i);
         }
    }
}

The output of this program is:

The value of i is: 10
The value of i is: 9
The value of i is: 8
The value of i is: 7
The value of i is: 6
The value of i is: 5
The value of i is: 4
The value of i is: 3
The value of i is: 2

In the above program:
int i=1 is initialization expression
i>1 is condition(Boolean expression)
i– Decrement operation

Java Nested for loop

A for loop inside another for loop is called nested for loop. Let’s take an example to understand the concept of nested for loop. In this example, we are printing a pattern using nested for loop.

public class JavaExample {
  public static void main(String[] args) {
    //outer loop
    for(int i=1;i<=6;i++){
      //inner loop
      for(int j=1;j<=i;j++){
        System.out.print("* ");
      }
      // this is to move the cursor to new line
      // to print the next row of the pattern
      System.out.println();
    }
  }
}

Output:
Java for loop example

Infinite for loop

A loop that never stops executing is called infinite loop. This happens when the condition expression defined in loop never returns false. The following example will help you understand the importance of Boolean expression and increment/decrement operation co-ordination:

class ForLoopExample2 {
    public static void main(String args[]){
         for(int i=1; i>=1; i++){
              System.out.println("The value of i is: "+i);
         }
    }
}

This is an infinite loop as the condition would never return false. The initialization step is setting up the value of variable i to 1, since we are incrementing the value of i, it would always be greater than 1 (the Boolean expression: i>1) so it would never return false. This would eventually lead to the infinite loop condition. Thus it is important to see the co-ordination between Boolean expression and increment/decrement operation to determine whether the loop would terminate at some point of time or not.

Here is another example of infinite for loop:

// infinite loop
for ( ; ; ) {
    // statement(s)
}

Example: Iterate an array using for loop

Let’s see another example of for loop. Here we are iterating and displaying array elements using the for loop.

class ForLoopExample3 {
    public static void main(String args[]){
         int arr[]={2,11,45,9};
         //i starts with 0 as array index starts with 0 too
         for(int i=0; i<arr.length; i++){
              System.out.println(arr[i]);
         }
    }
}

Output:

2
11
45
9

Enhanced For loop

Enhanced for loop is another way of defining a loop. This is especially useful when you want to iterate array, ArrayList and other collections classes. Tt is easy to read and write.

Let’s take the same example that we have seen above. We are rewriting it using enhanced for loop.

class ForLoopExample3 {
   public static void main(String args[]){
      int arr[]={2,11,45,9};
      for (int num : arr) {
         System.out.println(num);
      }
   }
}

Output:

2
11
45
9

Note: In the above example, I have declared the num as int in the enhanced for loop. This will change depending on the data type of array. For example, the enhanced for loop for string type would look like this:

String arr[]={"hi","hello","bye"};
for (String str : arr) {
         System.out.println(str);
}

Check out these java programming examples related to for loop:

  1. Java Program to find sum of natural numbers using for loop
  2. Java Program to find factorial of a number using loops
  3. Java Program to print Fibonacci Series using for loop
❮ PreviousNext ❯

Top Related Articles:

  1. Logical Operators in Java with Examples
  2. How to Compile and Run your First Java Program
  3. Java 9 – Factory methods to create Immutable Map
  4. Java 8 – Get Current Date and Time
  5. Java Integer byteValue() Method

About the Author

I have 15 years of experience in the IT industry, working with renowned multinational corporations. Additionally, I have dedicated over a decade to teaching, allowing me to refine my skills in delivering information in a simple and easily understandable manner.

– Chaitanya

Comments

  1. Harsh bhatnagar says

    September 27, 2015 at 4:53 AM

    I really appreciate and recommend this website to all the beginners and experienced as well. As i find it very ease in learning java, i’ve been in touch with the same for past 1yr but never been so comfortable with it. But after reading the few tutorials on this website i realized that, my concepts weren’t that much clear which i feel have been cleared after hitting these tutorials.
    Thanks –

    Reply
  2. Sasidhar says

    November 12, 2015 at 7:11 AM

    Very Helpful for beginners…As I am from a Non-IT background in my graduation, this site has helped me a lot…Add more sample & simple programs so that we can know more.
    Great going guys…keep it up :)

    Reply
  3. shashi says

    June 25, 2016 at 3:52 PM

    I think this array declaration is wrong.it can’t be like this.
    int arr[4]={2,11,45,9};
    It should be like this
    int arr[]={2,11,45,9};

    Reply
    • Syed Bilal says

      September 2, 2016 at 7:19 PM

      Both ways are correct. He declared and FIXED the size of array to 4 and if I come to your point, you can declare any number of members in your array!. Your concept is good for Multidimensional Array but for Single array.. Always declare the size of array!.

      Reply
    • Dragica says

      November 24, 2016 at 9:39 AM

      That’s right!

      Reply
    • Wuu says

      November 26, 2016 at 12:10 PM

      thanks, your comment is helping me a lot.

      Reply
      • king says

        March 20, 2017 at 6:36 PM

        i think first one was right .
        You can right like this :
        int [] array = new int[4];
        array ={2,11,45,9};

        Reply
  4. azhar says

    March 30, 2017 at 2:56 AM

    I want a real life example. For all the loops can any one help me out

    Reply
  5. Unknown says

    June 15, 2017 at 6:37 PM

    This is one of the best sites for learning java. Concepts are made very clear and explained in such a simple way. Wonderful way of teaching. Thank you so much!

    Reply

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Java Tutorial

Java Introduction

  • Java Index
  • Java Introduction
  • History of Java
  • Features of Java
  • C++ vs Java
  • JDK vs JRE vs JVM
  • JVM - Java Virtual Machine
  • First Java Program
  • Variables
  • Data Types
  • Operators

Java Flow Control

  • Java If-else
  • Java Switch-Case
  • Java For loop
  • Java while loop
  • Java do-while loop
  • Continue statement
  • break statement

Java Arrays

  • Java Arrays

OOPs Concepts

  • OOPs Concepts
  • Constructor
  • Java String
  • Static keyword
  • Inheritance
  • Types of inheritance
  • Aggregation
  • Association
  • Super Keyword
  • Method overloading
  • Method overriding
  • Overloading vs Overriding
  • Polymorphism
  • Types of polymorphism
  • Static and dynamic binding
  • Abstract class and methods
  • Interface
  • Abstract class vs interface
  • Encapsulation
  • Packages
  • Access modifiers
  • Garbage Collection
  • Inner classes
  • Static import
  • Static constructor

Java Exception Handling

  • Exception handling
  • Java try-catch
  • Java throw
  • Java throws
  • Checked and Unchecked Exceptions
  • Jav try catch finally
  • Exception Examples
  • Exception Propagation

Collections Framework

  • Collections in Java
  • Java ArrayList
  • Java LinkedList
  • Java Vector
  • Java HashSet
  • Java LinkedHashSet
  • Java TreeSet
  • Java HashMap
  • Java TreeMap
  • Java LinkedHashMap
  • Java Queue
  • Java PriorityQueue
  • Java Deque
  • Comparable interface
  • Comparator interface
  • Collections Interview Questions

MORE ...

  • Java Scanner Class
  • Java 8 Features
  • Java 9 Features
  • Java Conversion
  • Java Date
  • Java Multithreading
  • Java I/O
  • Java Serialization
  • Java Regex
  • Java AWT
  • Java Swing
  • Java Enum
  • Java Annotations
  • Java main method
  • Java Interview Q

Copyright © 2012 – 2025 BeginnersBook . Privacy Policy . Sitemap