Source code analysis of collection classes in Java language

Source code analysis of Java language collection classes

Collection classes in Java language are very commonly used tools. They provide the implementation of some common data structures, such as lists, sets, queues, and maps. In the Java language, these collection classes are defined through interfaces, and the specific implementation is completed through classes. In this article, we will analyze the source code of Java language collection classes so that we can better understand their implementation.

Collection classes in Java language mainly include the following types: List, Set, Map and Queue. Among these collection classes, List is the most basic type. It can store ordered elements and can contain duplicate elements. Among them, the Java language provides two List implementation classes, namely ArrayList and LinkedList.

In Java language, ArrayList is a collection class based on array implementation. It uses a dynamic array internally to store elements. When elements are added or removed, ArrayList automatically expands or contracts the size of the array as needed. This process is very efficient because array access is very fast. LinkedList is a collection class based on linked list, which uses a doubly linked list internally to store elements. Its main advantage is that it is more efficient than ArrayList when adding and deleting elements, but its access speed is slower than ArrayList.

In addition to List, there is also a Set type collection class in the Java language. Set is an unordered collection that does not allow duplicate elements. The Java language provides several Set implementation classes, including HashSet, LinkedHashSet, and TreeSet. Among them, HashSet is a collection class implemented using a hash table, and its search speed is very fast. However, due to the characteristics of hash tables, the storage order of HashSet is uncertain. LinkedHashSet adds a doubly linked list to HashSet to maintain the order of elements. In this way, when using LinkedHashSet, the order of elements is maintained in insertion order. TreeSet is a collection class implemented based on red-black trees. It can sort elements and can use custom comparators to sort elements.

In addition to List and Set, there is also a Map type collection class in the Java language. Map is a collection of key-value pairs, which can find the corresponding value based on the key. The Java language provides several Map implementation classes, including HashMap, TreeMap, LinkedHashMap, etc. Among them, HashMap is a Map collection class implemented using a hash table, and its search speed is very fast. However, due to the characteristics of hash tables, the storage order of HashMap is uncertain. LinkedHashMap adds a doubly linked list to HashMap to maintain the order of elements. In this way, when using LinkedHashMap, the order of elements is maintained in insertion order. TreeMap is a Map collection class based on red-black trees. It can sort keys, and a custom comparator can be used to sort keys.

Finally, there is also a Queue type collection class in the Java language. Queue is a queue that can be used to store and manipulate elements. The Java language provides some Queue implementation classes, including LinkedList, ArrayDeque, PriorityQueue, etc. Among them, LinkedList and ArrayDeque are both queues implemented based on arrays or linked lists, and they are relatively efficient. PriorityQueue is a queue implemented using a heap, which can sort elements according to certain rules.

To sum up, the collection class in Java language is a very commonly used tool. They provide the implementation of some commonly used data structures and can facilitate the operation and management of elements. While we are proficient in the use of these collection classes, we also need to have a deep understanding of their implementation principles so that we can use them better.

The above is the detailed content of Source code analysis of collection classes in Java language. For more information, please follow other related articles on the PHP Chinese website!