Java : ListIterator with Examples

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]

final var iterator = list.listIterator();

System.out.println("-- next --");
while (iterator.hasNext()) {
    final var value = iterator.next();
    System.out.println(value);
}

// Result
// ↓
//-- next --
//aaa
//bbb
//ccc

System.out.println("-- previous --");
while (iterator.hasPrevious()) {
    final var value = iterator.previous();
    System.out.println(value);
}

// Result
// ↓
//-- previous --
//ccc
//bbb
//aaa

void add (E e)

Inserts the specified element into the list (optional operation).

final var list = new ArrayList<String>();
Collections.addAll(list, "aaa", "bbb", "ccc");

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

final var iterator = list.listIterator();
while (iterator.hasNext()) {
    final var value = iterator.next();
    iterator.add(value.toUpperCase());
}

System.out.println(list); // [aaa, AAA, bbb, BBB, ccc, CCC]

boolean hasNext ()

Returns true if this list iterator has more elements when traversing the list in the forward direction.

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]

final var iterator = list.listIterator();

System.out.println("-- next --");
while (iterator.hasNext()) {
    final var index = iterator.nextIndex();
    final var value = iterator.next();
    System.out.printf("index = %d, value = %s%n", index, value);
}

// Result
// ↓
//-- next --
//index = 0, value = aaa
//index = 1, value = bbb
//index = 2, value = ccc

boolean hasPrevious ()

Returns true if this list iterator has more elements when traversing the list in the reverse direction.

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]

final var iterator = list.listIterator(list.size());

System.out.println("-- previous --");
while (iterator.hasPrevious()) {
    final var index = iterator.previousIndex();
    final var value = iterator.previous();
    System.out.printf("index = %d, value = %s%n", index, value);
}

// Result
// ↓
//-- previous --
//index = 2, value = ccc
//index = 1, value = bbb
//index = 0, value = aaa

E next ()

Returns the next element in the list and advances the cursor position.

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]

final var iterator = list.listIterator();

System.out.println("-- next --");
while (iterator.hasNext()) {
    final var index = iterator.nextIndex();
    final var value = iterator.next();
    System.out.printf("index = %d, value = %s%n", index, value);
}

// Result
// ↓
//-- next --
//index = 0, value = aaa
//index = 1, value = bbb
//index = 2, value = ccc

int nextIndex ()

Returns the index of the element that would be returned by a subsequent call to next().

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]

final var iterator = list.listIterator();

System.out.println("-- next --");
while (iterator.hasNext()) {
    final var index = iterator.nextIndex();
    final var value = iterator.next();
    System.out.printf("index = %d, value = %s%n", index, value);
}

// Result
// ↓
//-- next --
//index = 0, value = aaa
//index = 1, value = bbb
//index = 2, value = ccc

E previous ()

Returns the previous element in the list and moves the cursor position backwards.

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]

final var iterator = list.listIterator(list.size());

System.out.println("-- previous --");
while (iterator.hasPrevious()) {
    final var index = iterator.previousIndex();
    final var value = iterator.previous();
    System.out.printf("index = %d, value = %s%n", index, value);
}

// Result
// ↓
//-- previous --
//index = 2, value = ccc
//index = 1, value = bbb
//index = 0, value = aaa

int previousIndex ()

Returns the index of the element that would be returned by a subsequent call to previous().

final var list = List.of("aaa", "bbb", "ccc");
System.out.println(list); // [aaa, bbb, ccc]

final var iterator = list.listIterator(list.size());

System.out.println("-- previous --");
while (iterator.hasPrevious()) {
    final var index = iterator.previousIndex();
    final var value = iterator.previous();
    System.out.printf("index = %d, value = %s%n", index, value);
}

// Result
// ↓
//-- previous --
//index = 2, value = ccc
//index = 1, value = bbb
//index = 0, value = aaa

void remove ()

Removes from the list the last element that was returned by next() or previous() (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.listIterator();
while (iterator.hasNext()) {
    final var value = iterator.next();
    if (value % 2 == 0) {
        iterator.remove();
    }
}

System.out.println(list); // [1, 3, 5]

void set (E e)

Replaces the last element returned by next() or previous() with the specified element (optional operation).

final var list = new ArrayList<String>();
Collections.addAll(list, "aaa", "bbb", "ccc");

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

final var iterator = list.listIterator();
while (iterator.hasNext()) {
    final var value = iterator.next();
    iterator.set(value.toUpperCase());
}

System.out.println(list); // [AAA, BBB, CCC]

forEachRemaining

Please see the link below.

• Iterator with Examples