Careeroza

Real World Example

Electricity Bill with Slabs

State electricity boards charge by slabs: the first units are cheap, later units cost more. Billing systems implement this with if / else if chains.

Example

public class Main {
    public static void main(String[] args) {
        int[] readings = {80, 180, 420};
        for (int units : readings) {
            double bill;
            if (units <= 100) {
                bill = units * 3.0;
            } else if (units <= 200) {
                bill = 100 * 3.0 + (units - 100) * 4.5;
            } else if (units <= 400) {
                bill = 100 * 3.0 + 100 * 4.5 + (units - 200) * 6.0;
            } else {
                bill = 100 * 3.0 + 100 * 4.5 + 200 * 6.0 + (units - 400) * 8.0;
            }
            double fixedCharge = units > 300 ? 100 : 50;
            System.out.printf("%3d units -> energy Rs. %7.2f + fixed Rs. %.0f = Rs. %.2f%n",
                units, bill, fixedCharge, bill + fixedCharge);
        }
    }
}

Output

 80 units -> energy Rs.  240.00 + fixed Rs. 50 = Rs. 290.00
180 units -> energy Rs.  660.00 + fixed Rs. 50 = Rs. 710.00
420 units -> energy Rs. 2110.00 + fixed Rs. 100 = Rs. 2210.00