How to Iterate over a Set/HashSet without an Iterator?

How can I iterate over a Set/HashSet without the following?

Iterator iter = set.iterator();
while (iter.hasNext()) {
    System.out.println(iter.next());
}

Solution 1:

You can use an enhanced for loop:

Set<String> set = new HashSet<String>();

//populate set

for (String s : set) {
    System.out.println(s);
}

Or with Java 8:

set.forEach(System.out::println);

There are at least six additional ways to iterate over a set. The following are known to me:

Method 1

// Obsolete Collection
Enumeration e = new Vector(movies).elements();
while (e.hasMoreElements()) {
  System.out.println(e.nextElement());
}

Method 2

for (String movie : movies) {
  System.out.println(movie);
}

Method 3

String[] movieArray = movies.toArray(new String[movies.size()]);
for (int i = 0; i < movieArray.length; i++) {
  System.out.println(movieArray[i]);
}

Method 4

// Supported in Java 8 and above
movies.stream().forEach((movie) -> {
  System.out.println(movie);
});

Method 5

// Supported in Java 8 and above
movies.stream().forEach(movie -> System.out.println(movie));

Method 6

// Supported in Java 8 and above
movies.stream().forEach(System.out::println);

This is the HashSet which I used for my examples:

Set<String> movies = new HashSet<>();
movies.add("Avatar");
movies.add("The Lord of the Rings");
movies.add("Titanic");

Converting your set into an array may also help you for iterating over the elements:

Object[] array = set.toArray();

for(int i=0; i<array.length; i++)
   Object o = array[i];