Java for Loop

In computer programming, loops are used to repeat a block of code. For example, if you want to show a message 100 times, then rather than typing the same code 100 times, you can use a loop.

In Java, there are three types of loops.

This tutorial focuses on the for loop. You will learn about the other types of loops in the upcoming tutorials.

Java for Loop

Java for loop is used to run a block of code for a certain number of times. The syntax of for loop is:

for (initialExpression; testExpression; updateExpression) < // body of the loop >

The initialExpression initializes and/or declares variables and executes only once.
The condition is evaluated. If the condition is true , the body of the for loop is executed.
The updateExpression updates the value of initialExpression .
The condition is evaluated again. The process continues until the condition is false .

To learn more about the conditions, visit Java relational and logical operators.

Working of for <a href= loop in Java with flowchart" width="320" height="493" />

Example 1: Display a Text Five Times

// Program to print a text 5 times class Main < public static void main(String[] args) < int n = 5; // for loop for (int i = 1; i > >

Output

Java is fun Java is fun Java is fun Java is fun Java is fun

Here is how this program works.

Iteration	Variable	Condition: i	Action
1st	i = 1 n = 5	true	Java is fun is printed. i is increased to 2.
2nd	i = 2 n = 5	true	Java is fun is printed. i is increased to 3.
3rd	i = 3 n = 5	true	Java is fun is printed. i is increased to 4.
4th	i = 4 n = 5	true	Java is fun is printed. i is increased to 5.
5th	i = 5 n = 5	true	Java is fun is printed. i is increased to 6.
6th	i = 6 n = 5	false	The loop is terminated.

Example 2: Display numbers from 1 to 5

// Program to print numbers from 1 to 5 class Main < public static void main(String[] args) < int n = 5; // for loop for (int i = 1; i > >

Output

1 2 3 4 5

Here is how the program works.

Iteration	Variable	Condition: i	Action
1st	i = 1 n = 5	true	1 is printed. i is increased to 2.
2nd	i = 2 n = 5	true	2 is printed. i is increased to 3.
3rd	i = 3 n = 5	true	3 is printed. i is increased to 4.
4th	i = 4 n = 5	true	4 is printed. i is increased to 5.
5th	i = 5 n = 5	true	5 is printed. i is increased to 6.
6th	i = 6 n = 5	false	The loop is terminated.

Example 3: Display Sum of n Natural Numbers

// Program to find the sum of natural numbers from 1 to 1000. class Main < public static void main(String[] args) < int sum = 0; int n = 1000; // for loop for (int i = 1; i System.out.println("Sum java-exec"> // Program to find the sum of natural numbers from 1 to 1000. class Main < public static void main(String[] args) < int sum = 0; int n = 1000; // for loop for (int i = n; i >= 1; --i) < // body inside for loop sum += i; // sum = sum + i >System.out.println("Sum /java-programming/arrays">arrays and collections. For example,
 // print array elements class Main < public static void main(String[] args) < // create an array int[] numbers = ; // iterating through the array for (int number: numbers) < System.out.println(number); >> >
Output
3 7 5 -5
Here, we have used the for-each loop to print each element of the numbers array one by one.
In the first iteration of the loop, number will be 3, number will be 7 in second iteration and so on.
Java Infinite for Loop
If we set the test expression in such a way that it never evaluates to false , the for loop will run forever. This is called infinite for loop. For example,
// Infinite for Loop class Infinite < public static void main(String[] args) < int sum = 0; for (int i = 1; i > >
Also Read:

  Enhanced For Loop
  Nested Loop
  Break Statement
  Continue Statement