for
Keyword in Java
The for
keyword in Java is one of the most commonly used control flow tools. It helps repeat a block of code a specific number of times. From looping through numbers to iterating over arrays, the for
loop is everywhere in real-world programming.
Syntax of the for
Loop
Here’s the basic structure of a traditional for
loop in Java:
for (initialization; condition; update) {
// Code to be executed
}
How It Works
- Initialization: Happens once before the loop starts. Typically used to declare and initialize a counter.
- Condition: Evaluated before each iteration. The loop continues only while this condition is true.
- Update: Executes after each iteration. Usually increments or decrements the loop counter.
Example 1: Counting from 1 to 5
public class ForLoopExample {
public static void main(String[] args) {
for (int i = 1; i <= 5; i++) {
System.out.println("Count: " + i);
}
}
}
Count: 1
Count: 2
Count: 3
Count: 4
Count: 5
Example 2: Decrementing the Loop
Loops can also count downwards. Let’s count from 5 to 1.
public class Countdown {
public static void main(String[] args) {
for (int i = 5; i > 0; i--) {
System.out.println("Countdown: " + i);
}
}
}
Countdown: 5
Countdown: 4
Countdown: 3
Countdown: 2
Countdown: 1
Enhanced for
Loop (for-each)
Java also supports an enhanced for
loop—commonly called the for-each loop. It simplifies iteration over arrays and collections.
Syntax:
for (type variable : arrayOrCollection) {
// Code to execute
}
Example 3: Iterating Over an Array
public class ForEachExample {
public static void main(String[] args) {
String[] fruits = { "Apple", "Banana", "Cherry" };
for (String fruit : fruits) {
System.out.println("Fruit: " + fruit);
}
}
}
Fruit: Apple
Fruit: Banana
Fruit: Cherry
When to Use the for
Loop
The for
loop is a great choice when:
- You know how many times you need to repeat an action.
- You are working with counters or fixed-size iterations.
- You want tight control over initialization and updates.
Real-World Analogy
Think of a for
loop like counting the number of pushups you do. You start at 1 (initialization), keep going until you hit 10 (condition), and increase your count after each pushup (update).
Common Mistakes to Avoid
- Infinite loops: If you forget to update your loop counter or provide a faulty condition, the loop may never end.
- Off-by-one errors: These happen when you loop one time too few or too many.