February 22, 2024
April 9, 2022
Iterator (Java SE 21 & JDK 21) with Examples.
You will find code examples on most Iterator<E> methods.
Summary
An iterator over a collection. Iterator takes the place of Enumeration in the Java Collections Framework.
final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]
final var iterator = list.iterator();
System.out.println("-- next --");
while (iterator.hasNext()) {
final var value = iterator.next();
System.out.println(value);
}
// Result
// ↓
//-- next --
//aaa
//bbb
//ccc
Methods
default void forEachRemaining (Consumer<? super E> action)
Performs the given action for each remaining element until all elements have been processed or the action throws an exception.
final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]
final var iterator = list.iterator();
System.out.println("-- forEachRemaining --");
iterator.forEachRemaining(value -> {
System.out.println(value);
});
// Result
// ↓
//-- forEachRemaining --
//aaa
//bbb
//ccc
boolean hasNext ()
Returns true if the iteration has more elements.
final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]
final var iterator = list.iterator();
System.out.println("-- next --");
while (iterator.hasNext()) {
final var value = iterator.next();
System.out.println(value);
}
// Result
// ↓
//-- next --
//aaa
//bbb
//ccc
E next ()
Returns the next element in the iteration.
Please see hasNext().
default void remove ()
Removes from the underlying collection the last element returned by this iterator (optional operation).
final var list = new ArrayList<Integer>();
Collections.addAll(list, 1, 2, 3, 4, 5, 6);
System.out.println(list); // [1, 2, 3, 4, 5, 6]
final var iterator = list.iterator();
while (iterator.hasNext()) {
final var value = iterator.next();
if (value % 2 == 0) {
iterator.remove();
}
}
System.out.println(list); // [1, 3, 5]
Related posts
- API Examples