10 Java Fundamentals | For Loop in Java | By Dummy for Dummies
public class ForLoopDemo {
public static void main(String[] args) {
// Print numbers 1 to 5
for (int i = 1; i < 6; i++) {
System.out.println("Number: " + i);
}
System.out.println("Loop exited!");
}
}⦿ The code sets i to be 1, then check if it's smaller than 6, then update it by INCREMENTING for next iteration.
public class ReverseForLoop {
public static void main(String[] args) {
// Print numbers 5 to 1
for (int i = 5; i > 0; i--) {
System.out.println("Number: " + i);
}
System.out.println("Loop exited!");
}
}⦿ The code sets i to be 5, then check if it's greater than 0, then update it by DECREMENTING for next iteration.
POINTS TO REMEMBER
public class EvenNumbers {
public static void main(String[] args) {
// Print even numbers from 2 to 10
for (int i = 2; i <= 10; i += 2) {
System.out.println("Even: " + i);
}
System.out.println("Done printing evens!");
}
}It prints 10, because the condition is i <= 10 . Therefore as long as i is less than or equal to 10, the loop will run
EXERCISE
Let's do an exercise for what we studied in this post. Study this code, break it down, analyze it and identify the concepts used here. It would be even better if you write down your observations and make a mini report on it.
import java.util.Scanner;
public class ForLoopExercise {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
System.out.println("=== For Loop Practice ===");
System.out.print("Enter a small positive integer (n): ");
int n = sc.nextInt();
System.out.print("Enter a number for multiplication table (m): ");
int m = sc.nextInt();
// 1) Count from 1 to n
System.out.println("\n-- 1) Count from 1 to n --");
for (int i = 1; i <= n; i++) {
System.out.println("Number: " + i);
}
// 2) Even numbers from 2 to n (step update)
System.out.println("\n-- 2) Even numbers from 2 to n (i += 2) --");
for (int i = 2; i <= n; i += 2) {
System.out.println("Even: " + i);
}
// 3) Reverse count from n to 1
System.out.println("\n-- 3) Reverse count from n to 1 --");
for (int i = n; i >= 1; i--) {
System.out.println("Rev: " + i);
}
// 4) Sum and average of 1..n
System.out.println("\n-- 4) Sum and average of 1..n --");
int sum = 0;
for (int i = 1; i <= n; i++) {
sum += i; // accumulate
}
System.out.println("Sum: " + sum);
System.out.printf("Average: %.2f\n", (n > 0) ? (double) sum / n : 0.0);
// 5) Multiplication table for m (1..10)
System.out.println("\n-- 5) Multiplication table of " + m + " --");
for (int i = 1; i <= 10; i++) {
System.out.println(m + " x " + i + " = " + (m * i));
}
sc.close();
}
}
MINI PROJECT: (For Loop - Multiplication Table)
Your project is to create a simple Java program that prints the multiplication table of any number using a for loop. The program should ask the user to enter a number. Then it should use a for loop to print the table of that number from 1 to 10.
Example:
If the user enters 6, the output should be:
6 x 1 = 6
6 x 2 = 12
6 x 3 = 18
…
6 x 10 = 60
While writing the program, make sure you use:
⦿ Scanner for input
⦿ A for loop that runs from 1 to 10
⦿ printf or println to format the output properly
EXAMPLE OUTPUT: