Here’s a detailed textual diagram of the Java Collection Framework hierarchy with explanations at each level. I’ve included interfaces, abstract classes, and commonly used implementations.
java.lang.Object | +-- java.util.Collection<E> (root interface for collections) | +-- java.util.List<E> // Ordered collection (allows duplicates) | | | +-- java.util.AbstractList<E> // Partial implementation | | | | | +-- java.util.ArrayList<E> | | +-- java.util.Vector<E> | | | | | +-- java.util.Stack<E> | | | +-- java.util.LinkedList<E> // Doubly-linked list, also implements Deque<E> | +-- java.util.Set<E> // No duplicate elements | | | +-- java.util.AbstractSet<E> // Partial implementation | | | +-- java.util.HashSet<E> | +-- java.util.LinkedHashSet<E> | +-- java.util.TreeSet<E> // SortedSet implementation | +-- java.util.Queue<E> // FIFO ordering, allows element insertion/removal at ends | | | +-- java.util.Deque<E> // Double-ended queue | | | +-- java.util.ArrayDeque<E> | +-- java.util.LinkedList<E> // LinkedList also implements List<E> | +-- java.util.SortedSet<E> // Extends Set<E>, maintains sorted order | | | +-- java.util.NavigableSet<E> // Extends SortedSet<E>, provides navigation methods | | | +-- java.util.TreeSet<E> | +-- java.util.concurrent.ConcurrentMap (for thread-safe maps) java.util.Map<K,V> (not a Collection, but part of framework) | +-- java.util.HashMap<K,V> +-- java.util.LinkedHashMap<K,V> +-- java.util.TreeMap<K,V> // Implements NavigableMap<K,V> +-- java.util.Hashtable<K,V> | +-- java.util.concurrent.ConcurrentHashMap<K,V>