// Simple program that demonstrates sorting a list twice and seeing if the
// second sort preserves the order of the first for values that are considered
// equal.

import java.util.*;

public class StableSort {
    public static void main(String[] args) {
        // construct the list and sort it alphabetically
        String[] words = 
            {"four", "score", "and", "seven", "years", "ago", "our", "fathers",
             "brought", "forth", "on", "this", "continent", "a", "new",
             "nation", "conceived", "in", "liberty", "and", "dedicated", "to",
             "the", "proposition", "that", "all", "men", "are", "created",
             "equal"};
        System.out.println("before simple sort = " + Arrays.toString(words));
        Arrays.sort(words);
        System.out.println("after simple sort = " + Arrays.toString(words));

        // now sort a second time by sorting on string length (shorter strings
        // coming before longer strings)...the big question is whether words of
        // a given length will appear in alphabetical order (meaning that the
        // relative order from the previous sort was preserved)
        Arrays.sort(words, (a, b) -> a.length() - b.length());
        System.out.println("after length sort = " + Arrays.toString(words));

        // The second call on Arrays.sort uses a Java 8 feature known as a
        // lambda.  The following is a second equivalent version that uses
        // different Java 8 features.
        // Arrays.sort(words, Comparator.comparingInt(String::length));
    }
}