Java : SequencedCollection with Examples
Published : December 21, 2023
SequencedCollection (Java SE 21 & JDK 21) with Examples.
You will find code examples on most SequencedCollection methods.
Summary
A collection that has a well-defined encounter order, that supports operations at both ends, and that is reversible. The elements of a sequenced collection have an encounter order, where conceptually the elements have a linear arrangement from the first element to the last element.
final SequencedCollection<String> sc = new ArrayList<>();
sc.addLast("a");
sc.addLast("b");
sc.addLast("c");
System.out.println(sc); // [a, b, c]
System.out.println(sc.reversed()); // [c, b, a]
sc.addFirst("X");
sc.addFirst("Y");
sc.addFirst("Z");
System.out.println(sc); // [Z, Y, X, a, b, c]
System.out.println(sc.reversed()); // [c, b, a, X, Y, Z]
Methods
default void addFirst (E e)
Adds an element as the first element of this collection (optional operation).
final SequencedCollection<String> sc = new ArrayList<>();
sc.addFirst("aaa");
System.out.println(sc); // [aaa]
sc.addFirst("bbb");
System.out.println(sc); // [bbb, aaa]
sc.addFirst("ccc");
System.out.println(sc); // [ccc, bbb, aaa]
default void addLast (E e)
Adds an element as the last element of this collection (optional operation).
final SequencedCollection<String> sc = new ArrayList<>();
sc.addLast("aaa");
System.out.println(sc); // [aaa]
sc.addLast("bbb");
System.out.println(sc); // [aaa, bbb]
sc.addLast("ccc");
System.out.println(sc); // [aaa, bbb, ccc]
default E getFirst ()
Gets the first element of this collection.
final SequencedCollection<String> sc = new ArrayList<>();
sc.addLast("aaa");
System.out.println(sc); // [aaa]
System.out.println(sc.getFirst()); // aaa
sc.addLast("bbb");
System.out.println(sc); // [aaa, bbb]
System.out.println(sc.getFirst()); // aaa
sc.addLast("ccc");
System.out.println(sc); // [aaa, bbb, ccc]
System.out.println(sc.getFirst()); // aaa
final SequencedCollection<String> sc = new ArrayList<>();
System.out.println(sc); // []
try {
final var ret = sc.getFirst();
} catch (NoSuchElementException e) {
System.out.println("NoSuchElementException!");
}
// Result
// ↓
//NoSuchElementException!
default E getLast ()
Gets the last element of this collection.
final SequencedCollection<String> sc = new ArrayList<>();
sc.addLast("aaa");
System.out.println(sc); // [aaa]
System.out.println(sc.getLast()); // aaa
sc.addLast("bbb");
System.out.println(sc); // [aaa, bbb]
System.out.println(sc.getLast()); // bbb
sc.addLast("ccc");
System.out.println(sc); // [aaa, bbb, ccc]
System.out.println(sc.getLast()); // ccc
final SequencedCollection<String> sc = new ArrayList<>();
System.out.println(sc); // []
try {
final var ret = sc.getLast();
} catch (NoSuchElementException e) {
System.out.println("NoSuchElementException!");
}
// Result
// ↓
//NoSuchElementException!
default E removeFirst ()
Removes and returns the first element of this collection (optional operation).
final SequencedCollection<String> sc = new ArrayList<>();
sc.addLast("aaa");
sc.addLast("bbb");
sc.addLast("ccc");
System.out.println(sc); // [aaa, bbb, ccc]
System.out.println(sc.removeFirst()); // aaa
System.out.println(sc); // [bbb, ccc]
System.out.println(sc.removeFirst()); // bbb
System.out.println(sc); // [ccc]
System.out.println(sc.removeFirst()); // ccc
System.out.println(sc); // []
final SequencedCollection<String> sc = new ArrayList<>();
System.out.println(sc); // []
try {
final var ret = sc.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 SequencedCollection<String> sc = new ArrayList<>();
sc.addLast("aaa");
sc.addLast("bbb");
sc.addLast("ccc");
System.out.println(sc); // [aaa, bbb, ccc]
System.out.println(sc.removeLast()); // ccc
System.out.println(sc); // [aaa, bbb]
System.out.println(sc.removeLast()); // bbb
System.out.println(sc); // [aaa]
System.out.println(sc.removeLast()); // aaa
System.out.println(sc); // []
final SequencedCollection<String> sc = new ArrayList<>();
System.out.println(sc); // []
try {
final var ret = sc.removeLast();
} catch (NoSuchElementException e) {
System.out.println("NoSuchElementException!");
}
// Result
// ↓
//NoSuchElementException!
SequencedCollection<E> reversed ()
Returns a reverse-ordered view of this collection.
final SequencedCollection<String> sc = new ArrayList<>();
sc.addLast("aaa");
sc.addLast("bbb");
sc.addLast("ccc");
System.out.println(sc); // [aaa, bbb, ccc]
final var reversedSc = sc.reversed();
System.out.println(reversedSc); // [ccc, bbb, aaa]
System.out.println(reversedSc.reversed()); // [aaa, bbb, ccc]
Methods declared in Collection
add, addAll, clear, contains, containsAll, equals, hashCode, isEmpty, iterator, parallelStream, remove, removeAll, removeIf, retainAll, size, spliterator, stream, toArray, toArray, toArray
Please see the link below.
Methods declared in Iterable
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- API Examples