Loops - Java Programming in My Style

Thinking

Loops are a core part of programming logic. They allow a block of code to run repeatedly, reducing redundancy and improving efficiency.

Understanding how and when to use for, while, and do-while loops is essential for performing repetitive tasks such as iterating through arrays or executing a task until a condition is met.

Description

Java supports several types of loops to execute code repeatedly based on conditions:

for loop: Ideal when the number of iterations is known beforehand. It includes initialization, condition checking, and increment/decrement in one line.
while loop: Executes the loop body as long as the specified condition is true. Useful when the number of iterations is not known in advance.
do-while loop: Similar to the while loop but guarantees at least one execution, as the condition is evaluated after the loop body.

Loops improve program efficiency and are widely used in automation, data handling, and system processes.

Video Resources

Java Loops Tutorial

Learn the difference and usage of for, while, and do-while loops in Java.

View PDF

Examples (code)

Using a for loop


public class ForLoopExample {
    public static void main(String[] args) {
        for(int i = 1; i <= 5; i++) {
            System.out.println("Count: " + i);
        }
    }
}

Using a while loop


public class WhileLoopExample {
    public static void main(String[] args) {
        int i = 1;
        while(i <= 5) {
            System.out.println("Count: " + i);
            i++;
        }
    }
}

Using a do-while loop


public class DoWhileLoopExample {
    public static void main(String[] args) {
        int i = 1;
        do {
            System.out.println("Count: " + i);
            i++;
        } while(i <= 5);
    }
}

Real-World Applications

Data Processing

Loops are used to process records in databases and perform repetitive calculations.

Statistical Analysis

Repeated data aggregation or computation through arrays or lists using loops.

Automation Scripts

Automate tasks like sending emails or generating reports through looping mechanisms.

Interview Questions

Q1: What is the difference between a while and do-while loop?

Show Answer

A while loop checks the condition before executing the block, while a do-while loop executes the block once before checking the condition.

Q2: Can a for loop be infinite? How?

Show Answer

Yes, by omitting all conditions: for(;;) will create an infinite loop.

Q3: What are enhanced for-loops in Java?

Show Answer

Enhanced for-loops are used to iterate over arrays and collections: for (int num : numbers). They simplify iteration without managing index counters.