double number = 1000000.50;
String pattern = "'0' < ###,###,###.##";
DecimalFormat df = new DecimalFormat(pattern);
System.out.println(df.format(number));

pattern = "'Zahl ist' ''###,###,###.00''";
DecimalFormatSymbols symbols = new DecimalFormatSymbols();
symbols.setGroupingSeparator('/');
symbols.setDecimalSeparator('!');
df = new DecimalFormat(pattern, symbols);
System.out.println(df.format(number));

String numberStr = "1.000.000,00";
pattern = "###,###,###.##";
df = new DecimalFormat(pattern);
System.out.println(df.parse(numberStr));

// Umwandlung von Zahlen in Strings über Standard-Formatter
NumberFormat nf = NumberFormat.getInstance();
System.out.println(nf.format(number));
nf = NumberFormat.getCurrencyInstance();
System.out.println(nf.format(number));
nf = NumberFormat.getIntegerInstance();
System.out.println(nf.format(number));
nf = NumberFormat.getNumberInstance();
System.out.println(nf.format(number));
nf = NumberFormat.getPercentInstance();
System.out.println(nf.format(number));

// Erhalten eines Formatters ohne und mit Angabe einer Locale
nf = NumberFormat.getCurrencyInstance();
System.out.println(nf.format(number));
nf = NumberFormat.getCurrencyInstance(Locale.UK);
System.out.println(nf.format(number));