1. What is Percentage Calculation in Java?

Definition: Percentage calculation is a mathematical operation that determines what portion a part is of a whole, expressed as a value out of 100.

Purpose: It's commonly used in programming for various applications like calculating discounts, progress bars, statistics, and data analysis.

2. How Does the Calculation Work?

The calculator uses the formula:

Where:

• percentage — The result expressed as a percentage
• part — The portion of the whole you're measuring
• whole — The total or complete amount

Explanation: The part is divided by the whole to get a decimal value, which is then multiplied by 100 to convert it to a percentage.

3. Java Code Implementation

public class PercentageCalculator {
    public static double calculatePercentage(double part, double whole) {
        if (whole == 0) {
            throw new IllegalArgumentException("Whole cannot be zero");
        }
        return (part / whole) * 100;
    }
    
    public static void main(String[] args) {
        double part = 25.0;
        double whole = 200.0;
        double percentage = calculatePercentage(part, whole);
        System.out.printf("Percentage: %.2f%%", percentage);
    }
}

4. Using the Calculator

Tips: Enter the part and whole values (both must be positive numbers). The whole value cannot be zero.

5. Frequently Asked Questions (FAQ)

Q1: What happens if the whole is zero?
A: Division by zero is mathematically undefined. The Java code includes a check for this case.

Q2: How precise is the calculation?
A: The result is displayed with 2 decimal places, but Java's double type provides about 15-16 decimal digits of precision.

Q3: Can I calculate percentage decrease?
A: Yes, use (original - new) / original × 100. The result will be negative for decreases.

Q4: How to format the output in Java?
A: Use System.out.printf("%.2f%%", percentage) for 2 decimal places with percentage sign.

Q5: What about integer division issues?
A: In Java, dividing two integers performs integer division. Cast to double first: (double)part / whole × 100.