import java.util.Collections;
import java.util.Arrays;
import java.util.StringJoiner;

class Ideone {
	public static void main (String[] args) {
		Double[] numbers = { 5.0, 4.0, 6.2, 1.5 };
        Character[] letters = { 'a', 'v', 'c', 'd' };

        Collections.shuffle(Arrays.asList(numbers));
        Collections.shuffle(Arrays.asList(letters));

        StringJoiner joiner = new StringJoiner(", "); // from Java 8
        int length = Math.min(numbers.length, letters.length);
        for (int i = 0; i < length; i++) {
            joiner.add(letters[i].toString() + numbers[i]);
        }
        System.out.println(joiner.toString());
	}
}