The for loop
- Java course
- Beginner
- Lesson 42/116
- 4 min
Learn counting loops with for.
The for loop
The for loop repeats a fixed number of times. It has three parts: init, condition and step.
for (int i = 0; i < 5; i++) {
System.out.println(i);
}Here i starts at 0, repeats while it is below 5 and grows by 1 each step. The output is 0, 1, 2, 3, 4. i++ adds 1 to i each turn. When the condition is false, the loop ends.
for components
The three parts of a for loop are separated by semicolons: for (init; condition; step).
// Sum from 1 to 5
int sum = 0;
for (int i = 1; i <= 5; i++) {
sum += i;
}
System.out.println(sum); // 15Init runs once, the condition is tested at the start of each turn, and the step runs at the end. i <= 5 includes equality, so the loop runs five times from 1 to 5.
Practice Print 1 to 5
Write a Main class with a main method. With for (int i = 1; i <= 5; i++) print each i using System.out.println(i).
Sample solution
public class Main {
public static void main(String[] args) {
for (int i = 1; i <= 5; i++) {
System.out.println(i);
}
}
}Expected output
1 2 3 4 5
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How many times does for (int i = 0; i < 3; i++) { ... } run?
- 2
- 4
- 3 Correct answer
- Infinite
Explanation: It runs 3 times for i=0,1,2.
2 Complete the for loop
for (int i = 0; i ____ 5; i++) {
System.out.println(i);
}for (int i = 0; i < 5; i++) {
System.out.println(i);
}Explanation: i < 5 loops from 0 to 4.
3 Match the for concepts
| Term | Meaning |
|---|---|
int i = 0 |
Init |
i < 5 |
Condition |
i++ |
Step |
{ } |
Block |