JDK

1. What the Cloneable interface is. 2. What object cloning is. 3. How to implement object cloning: shallow cloning and deep cloning. 4. References.

Usage and implementation analysis of Integer, including immutability, valueOf, IntegerCache, and autoboxing behavior.

What ArrayList is, how to use it, and source analysis of construction, add, remove, resizing, and fail-fast behavior.

What Hashtable is, how to use it, and source analysis of construction, synchronized put/get/remove/containsKey, hashing, chaining, and rehashing.

Methods on Object, the equals/hashCode contract, and the difference between wait and sleep.

1. What PriorityQueue is. 2. Usage. 3. Source analysis: fields, constructors, heapify, insertion, deletion, sift-up, and sift-down. 4. Reference.

Serialization and deserialization in Java, custom readObject/writeObject hooks, implementation flow, serialVersionUID, and serialization algorithm.

What HashSet is, how to use it, source analysis, and summary.

1. What String is. 2. Usage. 3. Source analysis: class definition, constructors, constant pool, equals, toCharArray, toString, valueOf, intern, and substring. 4. Common questions. 5. References.

What LinkedList is, usage, and source analysis of its doubly linked list, add/remove operations, and node traversal.

What LinkedHashMap is, insertion-order and access-order usage, and source analysis of construction, put, get, contains, remove, and iteration.

How to create an immutable object.

Usage, constructor, fields, other methods, and summary of LinkedHashSet.

1. What It Is: a thread-safe mutable string, essentially StringBuilder with synchronized methods. 2. Usage. 3. Implementation analysis: constructor, append, toString, and substring.

Convert Array to List and List to Array.

Comparison of HashMap 1.7 and 1.8, HashMap and Hashtable, and TreeMap, LinkedHashMap, and HashMap.

Synchronized Set wrappers and the need for external synchronization during compound operations and iteration.

1. What It Is: a mutable, thread-unsafe string. 2. Usage. 3. Implementation analysis: constructor, append, toString, and substring.

Comparison of ArrayList and LinkedList, Vector and ArrayList, and SynchronizedList and Vector.

Synchronized Map wrappers, compound-operation atomicity, iteration locking, and concurrent alternatives.

What TreeSet is, usage, constructor, fields, other methods, and summary.

Comparison of StringBuilder, StringBuffer, and String.

1. What It Is: a thread-safe list. 2. Usage. 3. Source analysis: synchronizedList, SynchronizedList construction, mutex initialization, and synchronized method delegation.

What TreeMap is, usage, and source analysis of constructors, put, get, containsKey, and remove.

What Vector is, usage, source analysis, synchronization, and thread-safety limitations of compound operations.

fail-fast and fail-safe, Java iterator design, examples, implementation analysis, and summary.

1. Questions: hand-written HashMap, why capacity is converted to a power of 2, resizing, hash collisions, head insertion, concurrent resize loops, null keys, and ConcurrentModificationException. 2. References.

What HashMap is, usage, source analysis of construction, put, resize, treeification, get, containsKey, remove, containsValue, and differences from JDK 7.