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Java · Basics

Loops

Loops repeat work — for every item in a list, until a condition changes, or a fixed number of times.

Beginner 5 min Lesson 6 of 31Examples target Java 21 LTS (they also run on Java 25).
Before you start:Conditional Statements
0/31 in Java
On this page · 5 min · Beginner

On this page

  1. In simple words
  2. Learning objectives
  3. Explanation
  4. Code example
  5. Step by step
  6. Real-world use
  7. Common mistakes
  8. Best practices
  9. Remember this
  10. Practice exercise
  11. Mini quiz
  12. Related topics
  13. My notes
Reading time
5 min
Difficulty
Beginner
Updated
Oct 30, 2026

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Interview questions

In simple words#

A loop is a teacher calling roll: repeat “say the next name” for every student on the register, and stop when the list ends.

for
Counter-based loop.
for-each
Visit every element of an array or collection.
while / do-while
Repeat while a condition holds (do-while runs at least once).

Learning objectives#

  • Write counter loops
  • Iterate collections with for-each
  • Use while and do-while
  • Control loops with break and continue

Explanation#

for (int i = 0; i < n; i++) — when you need the index.

for (Type item : collection) — simplest way to visit every element.

while (condition) checks before each run; do { } while (condition) runs at least once.

break exits the loop; continue skips to the next iteration.

Code example: Totals, skipping and searching#

JavaTotals, skipping and searching Illustrative
int[] prices = {499, 1299, 0, 250, 899};


int total = 0;
for (int price : prices) {
    if (price == 0) continue;     // skip free items
    total += price;
}
System.out.println("Total: ₹" + total);


for (int i = 0; i < prices.length; i++) {
    if (prices[i] > 1000) {
        System.out.println("First expensive item at index " + i);
        break;
    }
}


int attempts = 0;
do {
    attempts++;
} while (attempts < 3);
System.out.println("Attempts: " + attempts);
Expected output
Total: ₹2947
First expensive item at index 1
Attempts: 3

This example is illustrative. Copy or download it and run it in your own environment; the expected output is shown above.

Step-by-step explanation#

  1. for-each adds every non-zero price.
  2. continue skips the free item.
  3. The indexed loop stops at the first price above 1000.
  4. do-while runs before checking the condition.

Real-world use case#

Batch jobs loop over thousands of orders to calculate totals and send invoices.

Common mistakes#

Off-by-one errors

Use i < length, not i <= length, to avoid ArrayIndexOutOfBoundsException.

Infinite while loops

Make sure the condition eventually becomes false.

Best practices#

  • Prefer for-each when the index isn’t needed
  • Keep loop bodies short
  • Consider streams for transformations
  • Avoid modifying a list while iterating it

Remember this#

for = index, for-each = items, while = condition.

break exits, continue skips.

i < length, not <=.

Practice exercise#

Your task: Print the multiplication table of 7 from 1 to 10.

Show solution
Java Illustrative
for (int i = 1; i <= 10; i++) {
    System.out.println("7 x " + i + " = " + (7 * i));
}

Mini quiz#

Loops quizMultiple choice Question 1 of 1

Which loop always runs its body at least once?

Score so far: 0/0

Want more? Practise all Java MCQs · Java interview questions

My notes#

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