The collection and data structure in the core framework in the Java class library

The collection and data structure in the core framework in the Java class library Collection and data structure are a very important part of Java programming, and they play an important role in the core framework of the Java class library.Java provides rich collection classes and data structures, including lists, queues, stacks, mapping, etc. These classes and data structures provide programmers with convenient operation methods and efficient memory management. In Java, the collection and data structures are mainly divided into two categories: Collection and Map.Collection is a collection of storage objects, mainly including list, set and queue.MAP is a mapping set with a key value pair. In Java, the commonly used collection classes include ArrayList, LinkedList, HashSet, TreeSet, HashMap, Treemap, etc.These collection classes provide a wealth of methods and operators, which is convenient for programmers to perform elements, deletion, deletion and investigation, and various collection operations. In addition to the commonly used collection class, Java also provides some special data structures, such as stacks and queue.The stack is an advanced data structure, and the queue is an advanced first -mover data structure.Java provides Stack and LinkedList to implement the operation of stacks and queues. In actual programming, programmers often need to use collection and data structures to store and operate data.Below is a simple Java code example, demonstrating how to use ArrayList and HashMap for data storage and operation: import java.util.ArrayList; import java.util.HashMap; public class CollectionDemo { public static void main(String[] args) { // Use ArrayList to store data ArrayList<String> list = new ArrayList<>(); list.add("apple"); list.add("banana"); list.add("cherry"); System.out.println (list.get (1)); // Output Banana // Use HashMap to store key value pairs HashMap<String, Integer> map = new HashMap<>(); map.put("apple", 10); map.put("banana", 20); map.put("cherry", 30); System.out.println (map.get ("banana"); // Output 20 } } In the above example, we first created an ArrayList and a HashMap to store string and key value pairs, and then operate and output the results.This shows the basic usage of collection and data structures in Java. In short, the collection and data structure played a very important role in the core framework of the Java class library. They provided programmers with a wealth of choice and convenient operation, which can greatly improve the efficiency and quality of the program.Therefore, programmers need to deeply understand and proficient in the collection and data structures in Java so that they can be used flexibly in actual programming.