Looping Statements in Java
Loops are used to execute a block of code multiple times based on a condition. Instead of writing the same code again and again, Java provides various loop constructs to simplify repetition.
Benefits of Loops in Java
- Avoids Code Repetition
- Instead of writing the same code multiple times, you can write it once inside a loop and execute it as many times as needed.
- Improves Code Readability
- Loops make your code cleaner, shorter, and easier to understand.
- Easy to Handle Large Tasks
- Great for processing large amounts of data like arrays, files, databases, etc.
- Supports Dynamic Logic
- You can run code based on changing conditions (e.g., read input until the user types "exit").
- Saves Time and Effort
- Reduces manual work for repetitive tasks such as printing patterns, calculating sums, etc.
- Helps with Automation
- Loops are the foundation of automated tasks, like sending multiple emails, generating reports, etc.
- Useful in Data Structures and Algorithms
- Essential for working with arrays, lists, sorting, searching, and more.
- Supports Scalability
- You can loop through 10 items or 10 million — just change the condition.
- Works with All Control Structures
- Can be combined with if, switch, break, continue, and even methods to make powerful logic.
- Mandatory in Real-world Applications
- Most real-world applications — like games, websites, operating systems — use loops at their core.
Java provides 4 types of loops to execute a block of code repeatedly:
- for loop
- while loop
- do-while loop
- Enhanced for loop (also called for-each loop)
Types of Loops in Java:
| Feature | for loop | while loop | do-while loop | Enhanced for loop |
|---|---|---|---|---|
| Entry/Exit Check | Entry | Entry | Exit | Entry |
| Use Case | Known count | Unknown count | At least once | Arrays/Collections |
| Supports index? | Yes | Yes | Yes | No (no index) |
| Executes if false? | No | No | Once | No |
| Simpler Syntax | Medium | Medium | Medium | Very Simple |
Summary:
- Why use loops?
- Avoid code repetition
- Clean & readable
- Automate tasks
- Work with data easily
- Java has 4 loops:
- for – fixed times
- while – unknown times
- do-while – runs at least once
- enhanced for – for arrays/lists