Java Container Tour: Container Basics Summary

Shows a complete diagram of the Java Container Class library, including abstract classes and legacy artifacts (excluding queue implementations).

The commonly used container is represented by a thick black wireframe, a dotted box represents an interface, a dashed box represents an abstract class, a solid wireframe represents a class, and a hollow arrow represents an implementation relationship. Produce indicates that arbitrary map objects can generate collection objects, and arbitrary collection objects can generate iterator objects.

Finally, we summarize the list, Set, map interface and the characteristics of each implementation class in tabular form:

	Characteristics	Implementation class	Implementing Class Attributes	Requirements for placed elements
List	Linear, ordered storage container with index access to element get (n)	ArrayList	Array implementations. Non-synchronous.
		Vector	Similar to ArrayList, synchronous.
		LinkedList	Doubly linked list. Non-synchronous.
Set	element cannot be duplicated, element must define equals () method	HashSet	Set for quick Find design	element must be defined hashcode ()
		TreeSet	The set of the hold order, the bottom is the tree structure	Element must implement comparable interface
		Linkedhashset	Internal use of the chain list to maintain the order of elements (inserted order)	element must be defined hashcode ()
Map	To save a key-value pair member, all keys in the map must define the Equals () method	HashMap	The implementation of MAP interface based on hash table to meet the common requirements	The key must have the appropriate hashcode (), and if you modify the Equals method, you need to modify the Hashcode method
		TreeMap	Sort by default according to natural order, or sort according to the comparator provided when the mapping is created	Key members require implementation of the Caparable interface, or use comparator to construct treemap. Key members are generally of the same type.
		Linkedhashmap	Similar to HashMap, but the order in which "key-value pairs" are obtained when iterating through is the order in which they are inserted or least recently used	Same as HashMap
		Identityhashmap	Hash map to compare "key value" with = = instead of equals ()	Members are judged equal by = =
		Weakhashmap	Weak key mapping, which allows you to release the object that the map points to
		Concurrenthashmap	Thread-Safe Map

(1) The behavior of various queue and stack can be fully supported by LinkedList, the above table does not contain a queue.

(2) But any hash-related, it will inevitably be designed to the Hashcode method, because the return of the hash code to calculate the position of the object in the hash table, but the general and tree-related, will inevitably design to the comparable interface, because it involves sorting.

(3) If you want to do a lot of random access, is to use ArrayList, if you want to frequently insert or delete elements from the middle of the table, you should use LinkedList. When traversing, for ArrayList preference get mode, LinkedList preferred iterator mode.

(4) collection inherits the Iterable interface, so all collection objects can iterate through the elements using the Foreach method. All collection objects Hiuforeach loops can work with any object that implements the Iterable interface.

Java Container Tour: Container Basics Summary