OnJava8-Examples/collections/UniqueWordsAlphabetic.java

// collections/UniqueWordsAlphabetic.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Producing an alphabetic listing
import java.util.*;
import java.nio.file.*;

public class UniqueWordsAlphabetic {
  public static void
  main(String[] args) throws Exception {
    List<String> lines = Files.readAllLines(
      Paths.get("SetOperations.java"));
    Set<String> words =
      new TreeSet<>(String.CASE_INSENSITIVE_ORDER);
    for(String line : lines)
      for(String word : line.split("\\W+"))
        if(word.trim().length() > 0)
          words.add(word);
    System.out.println(words);
  }
}
/* Output:
[A, add, addAll, added, args, B, C, class, collections,
contains, containsAll, D, E, F, false, from, G, H,
HashSet, I, import, in, J, java, K, L, M, main, N, new,
out, Output, println, public, remove, removeAll,
removed, Set, set1, set2, SetOperations, split, static,
String, System, to, true, util, void, X, Y, Z]
*/