Loops

COMP122 Lectures 2021-02-22

for Loops

These are used to repeat a block of code a fixed number of times:

for (initialisation;
	condition;
	update) {
		// stuff to repeat
}

Example

Print the first 10 integers:

for (int i = 1; i <= 10; i++) {
	System.out.println(i);
}

In this case the {} aren’t required as a single line statement is a block.

while Loops

while(condition) {
	// stuff to repeat
}

The condition is tested before running the loop. do while loops check after.

Example

This program adds integers until the user types 0:

//import java.util.Scanner;
Scanner input = new Scanner();

int total = 0;
int value = input.nextInt();

while (value != 0) {
	total += value;
	value = input.nextInt();
}
System.out.println(total);