spring-boot-demo/pdf-invoice/src/main/java/com/ankurm/pdfinvoice/Money.java

package com.ankurm.pdfinvoice;

import java.math.BigDecimal;
import java.text.NumberFormat;
import java.util.Locale;

/**
 * Rupee formatting with Indian digit grouping (12,34,567.00), shared by all three writers.
 * It is a class of our own because Thymeleaf 3.1 refuses to call methods on {@code java.*} types
 * from a template expression ("Calling method 'format' is forbidden for type DecimalFormat").
 */
public final class Money {

    private Money() {}

    public static String inr(BigDecimal v) {
        NumberFormat f = NumberFormat.getNumberInstance(Locale.of("en", "IN"));
        f.setMinimumFractionDigits(2);
        f.setMaximumFractionDigits(2);
        return "₹ " + f.format(v);
    }

    /** Template-friendly instance wrapper: {@code ${money.inr(x)}}. */
    public static final class Fmt {
        public String inr(BigDecimal v) {
            return Money.inr(v);
        }
    }
}