Rounding operations using MathContext and RoundingMode

import java.math.BigDecimal;
import java.math.RoundingMode;

public class BigDecimalRoundingDemo {
    public static void main(String[] args) {
        BigDecimal value = new BigDecimal("123.456789");

        System.out.println("Original value: " + value);

        // Round to 2 decimal places with different rounding modes

        BigDecimal roundHalfUp = value.setScale(2, RoundingMode.HALF_UP);
        System.out.println("HALF_UP: " + roundHalfUp);  // 123.46

        BigDecimal roundHalfDown = value.setScale(2, RoundingMode.HALF_DOWN);
        System.out.println("HALF_DOWN: " + roundHalfDown); // 123.46

        BigDecimal roundHalfEven = value.setScale(2, RoundingMode.HALF_EVEN);
        System.out.println("HALF_EVEN: " + roundHalfEven); // 123.46

        BigDecimal roundUp = value.setScale(2, RoundingMode.UP);
        System.out.println("UP: " + roundUp); // 123.46

        BigDecimal roundDown = value.setScale(2, RoundingMode.DOWN);
        System.out.println("DOWN: " + roundDown); // 123.45

        BigDecimal roundCeiling = value.setScale(2, RoundingMode.CEILING);
        System.out.println("CEILING: " + roundCeiling); // 123.46

        BigDecimal roundFloor = value.setScale(2, RoundingMode.FLOOR);
        System.out.println("FLOOR: " + roundFloor); // 123.45

        // Attempt rounding with UNNECESSARY (throws exception if rounding required)
        try {
            BigDecimal noRounding = value.setScale(6, RoundingMode.UNNECESSARY);
            System.out.println("UNNECESSARY (no rounding needed): " + noRounding);
        } catch (ArithmeticException e) {
            System.out.println("UNNECESSARY rounding required exception: " + e.getMessage());
        }
    }
}