LocalesFormat Iterates over all locale available on current system and prints locale that use special characters to present digits. It also counts how many locales use dot and comma as a decimal delimiter. FormatterExercise compares performance of String.format() vs direct usage of Formatter class.

FormatterExercise.java

import java.util.Formatter;

public class FormatterExercise {
	private static int n = 1_000_000;
	
	public static void main(String[] args) throws InterruptedException {
		long before = System.nanoTime();
		str();
		long after = System.nanoTime();
		System.out.println((after - before)/1_000_000);

		before = System.nanoTime();
		fmt();
		after = System.nanoTime();
		System.out.println((after - before)/1_000_000);
	}

	public static CharSequence str() {
		StringBuilder buf = new StringBuilder();
		for (int i = 0; i < n; i++) {
			buf.append(String.format("%d\n", 1));
		}
		return buf;
	}

	public static CharSequence fmt() {
		StringBuilder buf = new StringBuilder();
		Formatter fmt = new Formatter(buf);
		for (int i = 0; i < n; i++) {
			fmt.format("%d\n", 1);
		}
		return buf;
	}
}

LocalesFormat.java

import java.util.Locale;

public class LocalesFormat {
        public static void main(String[] args) {
                int decimalDot = 0;
                int decimalComma = 0;
                for (Locale locale : Locale.getAvailableLocales()) {
                        String one = String.format(locale, "%d", 1);
                        if (!"1".equals(one)) {
                                System.out.println("\t" +locale + ": " + one);
                        }
                        String pi = String.format(locale, "%.2f", 3.14);
                        if (pi.contains(".")) {
                                decimalDot++;
                        } else if(pi.contains(",")) {
                                decimalComma++;
                        } else {
                                System.out.println("\t" +locale + ": " + pi);
                        }
                }

                System.out.println(String.format("Total locales: %d\nDecimal dot: %d\nDecimal comma: %d", Locale.getAvailableLocales().length, decimalDot, decimalComma));
        }
}