Java for loop

Java for loop is used to repeat execution of the statement(s) until a certain condition holds true. for is a keyword in Java programming language.

Java for loop syntax

1. for (/* Initialization of variables */ ; /*Conditions to test*/ ; /* Increment(s) or decrement(s) of variables */){
2.   // Statements to execute, i.e., Body of a for loop
3. }

You can initialize multiple variables, test many conditions and perform increments or decrements on many variables according to requirement. Please note that all three components of a for loop are optional. For example, following for loop prints "Java programming" indefinitely.

1. // Infinite for loop
2. for ( ; ; ) {
3.   System.out.println("Java programming");
4. }

You can terminate an infinite loop by pressing Ctrl+C.

Simple for loop example in Java

Example program below uses for loop to print first 10 natural numbers i.e. from 1 to 10.

1. //Java for loop program
2. class ForLoop {
3.   public static void main(String[] args) {
4.     int c;
5.    
6.     for (c = 1; c <= 10; c++) {
7.       System.out.println(c);
8.     }
9.   }
10. }

Output of program:

Java for loop example to print stars in console

Following star pattern is printed
*
**
***
****
*****

1. class Stars {
2.   public static void main(String[] args) {
3.     int row, numberOfStars;
4.    
5.     for (row = 1; row <= 10; row++) {
6.       for(numberOfStars = 1; numberOfStars <= row; numberOfStars++) {
7.         System.out.print("*");
8.       }
9.       System.out.println(); // Go to next line
10.     }
11.   }
12. }

This program uses nested for loops i.e. for loop inside a for loop to print the pattern of stars. You can also use spaces to create another pattern, it is left for you as an exercise.

Output of program: