Custom Decimal formatting in Java with custom decimal separator and thousand separator, forced fraction and decimal places options, regardless of locale.

CustomDecimalFormat.java

import java.text.DecimalFormat;
import java.text.DecimalFormatSymbols;
import java.text.NumberFormat;
import java.util.Currency;
import java.util.Locale;

public class CustomDecimalFormat {
  
    public static DecimalFormat prepareFormat(char decimalSeparator, char thousandSeparator, boolean forceFraction, byte decimalPlaces){
        String pattern = "#,###.";
        if(decimalPlaces <= 0){
            pattern = pattern.substring(0, pattern.length() - 1);
        } else if (forceFraction) {
            for (byte i = 0; i < decimalPlaces; i++) {
                pattern += "0";
            }
        } else {
            for (byte i = 0; i < decimalPlaces; i++) {
                pattern += "#";
            }
        }
        DecimalFormatSymbols symbols = new DecimalFormatSymbols(Locale.US);
        symbols.setDecimalSeparator(decimalSeparator);
        symbols.setGroupingSeparator(thousandSeparator);
        DecimalFormat decimalFormat = new DecimalFormat(pattern, symbols);
        return decimalFormat;
    }
    
    public static void test(){
        DecimalFormat decimalFormat = prepareFormat(',', '.', false, (byte) 2); 
        System.out.println(decimalFormat.format(1521119122.346)); // 1.521.119.122,35
    }

}