collection-framework

Java Collection Hierarchy

Java Collection Framework provides a set of data structures and interfaces that developers can use to manage and manipulate collections of objects.

• ArrayList

• LinkedList

• Vector

• Stack

• HashSet

• LinkedHashSet

• TreeSet

• HashMap

• LinkedHashMap

• TreeMap

• Hashtable

• Queue (interface)

• PriorityQueue

• ArrayDeque

Common methods for classes in Collection framework

Common methods in Collection Interface include :

• add

• remove

• contains

• isEmpty

• size

• iterator

Iterator class

List<String> names = new ArrayList<>();
names.add("Alice");
names.add("Bob");
names.add("Charlie");

// Has a pointer to an element of the collection it is iterating over
Iterator<String> iterator = names.iterator();

while (iterator.hasNext()) {
    String name = iterator.next();
    System.out.println(name);

    // You can remove elements if needed with iterator.remove();
}