JavaFor Loop

Java For Loop

When you know exactly how many times you want to loop through a block of code, use thefor loop instead of awhile loop:

for (statement 1; statement 2; statement 3) { // code block to be executed}

Statement 1 is executed (one time) before the execution of the code block.

Statement 2 defines the condition for executing the code block.

Statement 3 is executed (every time) after the code block has been executed.

Print Numbers

The example below will print the numbers 0 to 4:

for (int i = 0; i < 5; i++) {
  System.out.println(i);
}

Example explained

• Statement 1 sets a variable before the loop starts:int i = 0
• Statement 2 defines the condition for the loop to run:i < 5. If the condition is true, the loop will run again; if it is false, the loop ends.
• Statement 3 increases a value each time the code block has run:i++

Print Even Numbers

This example prints even values between 0 and 10:

for (int i = 0; i <= 10; i = i + 2) {
  System.out.println(i);
}

Sum of Numbers

This example calculates the sum of numbers from 1 to 5:

int sum = 0;
for (int i = 1; i <= 5; i++) {
  sum = sum + i;
}
System.out.println("Sum is " + sum);

Countdown

This example prints a countdown from 5 to 1:

for (int i = 5; i > 0; i--) {
  System.out.println(i);
}

For Loop With False Condition

Just like awhile loop, afor loop may also never run. If the condition isfalse right from the start, the code inside the loop will be skipped entirely:

for (int i = 10; i < 5; i++) {  System.out.println("This will never be printed");}

In this example, the loop starts withi = 10. The conditioni < 5 is already false, so the loop body is skipped, and nothing is printed.