Java : NavigableSet with Examples

final NavigableSet<String> set = new TreeSet<>();
System.out.println(set); // []
System.out.println(set.isEmpty()); // true

set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]
System.out.println(set.size()); // 3

System.out.println(set.lower("a")); // null
System.out.println(set.lower("b")); // a
System.out.println(set.lower("c")); // b

System.out.println(set.higher("a")); // b
System.out.println(set.higher("b")); // c
System.out.println(set.higher("c")); // null

E ceiling (E e)

Returns the least element in this set greater than or equal to the given element, or null if there is no such element.

final NavigableSet<String> set = new TreeSet<>();
set.add("b");
set.add("d");
set.add("f");

System.out.println(set); // [b, d, f]

System.out.println(set.ceiling("a")); // b
System.out.println(set.ceiling("b")); // b
System.out.println(set.ceiling("c")); // d
System.out.println(set.ceiling("d")); // d
System.out.println(set.ceiling("e")); // f
System.out.println(set.ceiling("f")); // f
System.out.println(set.ceiling("g")); // null

Iterator<E> descendingIterator ()

Returns an iterator over the elements in this set, in descending order.

final NavigableSet<String> set = new TreeSet<>();
set.add("aaa");
set.add("bbb");
set.add("ccc");

System.out.println(set); // [aaa, bbb, ccc]

final var iterator = set.descendingIterator();

System.out.println("-- forEachRemaining --");
iterator.forEachRemaining(s -> {
    System.out.println(s);
});

// Result
// ↓
//-- forEachRemaining --
//ccc
//bbb
//aaa

NavigableSet<E> descendingSet ()

Returns a reverse order view of the elements contained in this set.

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

final var descSet = set.descendingSet();
System.out.println(descSet); // [c, b, a]

set.add("d");

System.out.println(set); // [a, b, c, d]
System.out.println(descSet); // [d, c, b, a]

descSet.remove("b");

System.out.println(set); // [a, c, d]
System.out.println(descSet); // [d, c, a]

E floor (E e)

Returns the greatest element in this set less than or equal to the given element, or null if there is no such element.

final NavigableSet<String> set = new TreeSet<>();
set.add("b");
set.add("d");
set.add("f");

System.out.println(set); // [b, d, f]

System.out.println(set.floor("a")); // null
System.out.println(set.floor("b")); // b
System.out.println(set.floor("c")); // b
System.out.println(set.floor("d")); // d
System.out.println(set.floor("e")); // d
System.out.println(set.floor("f")); // f
System.out.println(set.floor("g")); // f

SortedSet<E> headSet (E toElement)

Returns a view of the portion of this set whose elements are strictly less than toElement.

final NavigableSet<String> set = new TreeSet<>();
set.add("x");
set.add("y");
set.add("z");

System.out.println(set); // [x, y, z]

final var headSet = set.headSet("z");
System.out.println(headSet); // [x, y]

set.add("a");

System.out.println(set); // [a, x, y, z]
System.out.println(headSet); // [a, x, y]

headSet.remove("x");

System.out.println(set); // [a, y, z]
System.out.println(headSet); // [a, y]

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.headSet("a")); // []
System.out.println(set.headSet("b")); // [a]
System.out.println(set.headSet("c")); // [a, b]
System.out.println(set.headSet("d")); // [a, b, c]

NavigableSet<E> headSet (E toElement, boolean inclusive)

Returns a view of the portion of this set whose elements are less than (or equal to, if inclusive is true) toElement.

final NavigableSet<String> set = new TreeSet<>();
set.add("x");
set.add("y");
set.add("z");

System.out.println(set); // [x, y, z]

final var headSet = set.headSet("y", true);
System.out.println(headSet); // [x, y]

set.add("a");

System.out.println(set); // [a, x, y, z]
System.out.println(headSet); // [a, x, y]

headSet.remove("x");

System.out.println(set); // [a, y, z]
System.out.println(headSet); // [a, y]

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.headSet("a")); // []
System.out.println(set.headSet("a", true)); // [a]

System.out.println(set.headSet("b")); // [a]
System.out.println(set.headSet("b", true)); // [a, b]

System.out.println(set.headSet("c")); // [a, b]
System.out.println(set.headSet("c", true)); // [a, b, c]

System.out.println(set.headSet("d")); // [a, b, c]
System.out.println(set.headSet("d", true)); // [a, b, c]

E higher (E e)

Returns the least element in this set strictly greater than the given element, or null if there is no such element.

final NavigableSet<String> set = new TreeSet<>();
set.add("b");
set.add("d");
set.add("f");

System.out.println(set); // [b, d, f]

System.out.println(set.higher("a")); // b
System.out.println(set.higher("b")); // d
System.out.println(set.higher("c")); // d
System.out.println(set.higher("d")); // f
System.out.println(set.higher("e")); // f
System.out.println(set.higher("f")); // null
System.out.println(set.higher("g")); // null

Iterator<E> iterator ()

Returns an iterator over the elements in this set, in ascending order.

final NavigableSet<String> set = new TreeSet<>();
set.add("aaa");
set.add("bbb");
set.add("ccc");

System.out.println(set); // [aaa, bbb, ccc]

final var iterator = set.iterator();

System.out.println("-- forEachRemaining --");
iterator.forEachRemaining(s -> {
    System.out.println(s);
});

// Result
// ↓
//-- forEachRemaining --
//aaa
//bbb
//ccc

E lower (E e)

Returns the greatest element in this set strictly less than the given element, or null if there is no such element.

final NavigableSet<String> set = new TreeSet<>();
set.add("b");
set.add("d");
set.add("f");

System.out.println(set); // [b, d, f]

System.out.println(set.lower("a")); // null
System.out.println(set.lower("b")); // null
System.out.println(set.lower("c")); // b
System.out.println(set.lower("d")); // b
System.out.println(set.lower("e")); // d
System.out.println(set.lower("f")); // d
System.out.println(set.lower("g")); // f

E pollFirst ()

Retrieves and removes the first (lowest) element, or returns null if this set is empty (optional operation).

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.pollFirst()); // a
System.out.println(set); // [b, c]

System.out.println(set.pollFirst()); // b
System.out.println(set); // [c]

System.out.println(set.pollFirst()); // c
System.out.println(set); // []

System.out.println(set.pollFirst()); // null

E pollLast ()

Retrieves and removes the last (highest) element, or returns null if this set is empty (optional operation).

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.pollLast()); // c
System.out.println(set); // [a, b]

System.out.println(set.pollLast()); // b
System.out.println(set); // [a]

System.out.println(set.pollLast()); // a
System.out.println(set); // []

System.out.println(set.pollLast()); // null

default E removeFirst ()

Removes and returns the first element of this collection (optional operation).

final NavigableSet<String> set = new TreeSet<>();

set.add("aaa");
set.add("bbb");
set.add("ccc");

System.out.println(set); // [aaa, bbb, ccc]

System.out.println(set.removeFirst()); // aaa
System.out.println(set); // [bbb, ccc]

System.out.println(set.removeFirst()); // bbb
System.out.println(set); // [ccc]

System.out.println(set.removeFirst()); // ccc
System.out.println(set); // []

final NavigableSet<String> set = new TreeSet<>();
System.out.println(set); // []

try {
    var _ = set.removeFirst();
} catch (NoSuchElementException e) {
    System.out.println("NoSuchElementException!");
}

// Result
// ↓
//NoSuchElementException!

default E removeLast ()

Removes and returns the last element of this collection (optional operation).

final NavigableSet<String> set = new TreeSet<>();

set.add("aaa");
set.add("bbb");
set.add("ccc");

System.out.println(set); // [aaa, bbb, ccc]

System.out.println(set.removeLast()); // ccc
System.out.println(set); // [aaa, bbb]

System.out.println(set.removeLast()); // bbb
System.out.println(set); // [aaa]

System.out.println(set.removeLast()); // aaa
System.out.println(set); // []

final NavigableSet<String> set = new TreeSet<>();
System.out.println(set); // []

try {
    var _ = set.removeLast();
} catch (NoSuchElementException e) {
    System.out.println("NoSuchElementException!");
}

// Result
// ↓
//NoSuchElementException!

default NavigableSet<E> reversed ()

Returns a reverse-ordered view of this collection.

final NavigableSet<String> set = new TreeSet<>();

set.add("aaa");
set.add("bbb");
set.add("ccc");

System.out.println(set); // [aaa, bbb, ccc]

final var reversedSet = set.reversed();
System.out.println(reversedSet); // [ccc, bbb, aaa]

System.out.println(reversedSet.reversed()); // [aaa, bbb, ccc]

NavigableSet<E> subSet (E fromElement, boolean fromInclusive, E toElement, boolean toInclusive)

Returns a view of the portion of this set whose elements range from fromElement to toElement.

final NavigableSet<String> set = new TreeSet<>();
set.add("x");
set.add("y");
set.add("z");

System.out.println(set); // [x, y, z]

final var subSet = set.subSet("a", true, "y", true);
System.out.println(subSet); // [x, y]

set.add("a");

System.out.println(set); // [a, x, y, z]
System.out.println(subSet); // [a, x, y]

subSet.remove("x");

System.out.println(set); // [a, y, z]
System.out.println(subSet); // [a, y]

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.subSet("a", true, "c", true)); // [a, b, c]
System.out.println(set.subSet("a", true, "c", false)); // [a, b]
System.out.println(set.subSet("a", false, "c", true)); // [b, c]
System.out.println(set.subSet("a", false, "c", false)); // [b]

System.out.println(set.subSet("a", true, "a", false)); // []
System.out.println(set.subSet("a", true, "b", false)); // [a]
System.out.println(set.subSet("a", true, "c", false)); // [a, b]
System.out.println(set.subSet("a", true, "d", false)); // [a, b, c]

System.out.println(set.subSet("a", true, "d", false)); // [a, b, c]
System.out.println(set.subSet("b", true, "d", false)); // [b, c]
System.out.println(set.subSet("c", true, "d", false)); // [c]
System.out.println(set.subSet("d", true, "d", false)); // []

SortedSet<E> subSet (E fromElement, E toElement)

Returns a view of the portion of this set whose elements range from fromElement, inclusive, to toElement, exclusive.

final NavigableSet<String> set = new TreeSet<>();
set.add("x");
set.add("y");
set.add("z");

System.out.println(set); // [x, y, z]

final var subSet = set.subSet("a", "z");
System.out.println(subSet); // [x, y]

set.add("a");

System.out.println(set); // [a, x, y, z]
System.out.println(subSet); // [a, x, y]

subSet.remove("x");

System.out.println(set); // [a, y, z]
System.out.println(subSet); // [a, y]

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.subSet("a", "a")); // []
System.out.println(set.subSet("a", "b")); // [a]
System.out.println(set.subSet("a", "c")); // [a, b]
System.out.println(set.subSet("a", "d")); // [a, b, c]

System.out.println(set.subSet("a", "d")); // [a, b, c]
System.out.println(set.subSet("b", "d")); // [b, c]
System.out.println(set.subSet("c", "d")); // [c]
System.out.println(set.subSet("d", "d")); // []

SortedSet<E> tailSet (E fromElement)

Returns a view of the portion of this set whose elements are greater than or equal to fromElement.

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

final var tailSet = set.tailSet("b");
System.out.println(tailSet); // [b, c]

set.add("d");

System.out.println(set); // [a, b, c, d]
System.out.println(tailSet); // [b, c, d]

tailSet.remove("b");

System.out.println(set); // [a, c, d]
System.out.println(tailSet); // [c, d]

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.tailSet("a")); // [a, b, c]
System.out.println(set.tailSet("b")); // [b, c]
System.out.println(set.tailSet("c")); // [c]
System.out.println(set.tailSet("d")); // []

NavigableSet<E> tailSet (E fromElement, boolean inclusive)

Returns a view of the portion of this set whose elements are greater than (or equal to, if inclusive is true) fromElement.

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

final var tailSet = set.tailSet("a", false);
System.out.println(tailSet); // [b, c]

set.add("d");

System.out.println(set); // [a, b, c, d]
System.out.println(tailSet); // [b, c, d]

tailSet.remove("b");

System.out.println(set); // [a, c, d]
System.out.println(tailSet); // [c, d]

final NavigableSet<String> set = new TreeSet<>();
set.add("a");
set.add("b");
set.add("c");

System.out.println(set); // [a, b, c]

System.out.println(set.tailSet("a")); // [a, b, c]
System.out.println(set.tailSet("a", false)); // [b, c]

System.out.println(set.tailSet("b")); // [b, c]
System.out.println(set.tailSet("b", false)); // [c]

System.out.println(set.tailSet("c")); // [c]
System.out.println(set.tailSet("c", false)); // []

parallelStream, removeIf, stream, toArray

Please see the link below.

• Collection with Examples

forEach

Please see the link below.

• Iterable with Examples

add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, remove, removeAll, retainAll, size, toArray, toArray

Please see the link below.

• Set with Examples

addFirst, addLast, comparator, first, getFirst, getLast, last, spliterator

Please see the link below.

• SortedSet with Examples