Decrypting Java data structures: Mastering these data structures will allow you to program with twice the result with half the effort

The secret of Java data structures: mastering these data structures will make your programming more efficient. Specific code examples are needed

Introduction:
In the field of programming, data structures are A very important subject. Mastering appropriate data structures can greatly improve the efficiency and quality of programs. In the Java programming language, there are also some commonly used data structures. Today we will reveal these data structures together and attach specific code examples.

1. Array (Array):
   An array is a linear data structure that can store elements of the same type and be accessed by index. In Java, array is one of the most basic and commonly used data structures. The following is a sample code that demonstrates how to create, access and modify an array:

// 创建一个数组
int[] nums = new int[5];

// 初始化数组
nums[0] = 1;
nums[1] = 2;
nums[2] = 3;
nums[3] = 4;
nums[4] = 5;

// 访问数组元素
int firstNum = nums[0];
System.out.println("第一个元素是：" + firstNum);

// 修改数组元素
nums[0] = 10;
System.out.println("修改后的第一个元素是：" + nums[0]);

2. Linked List:
   Linked list is another common linear data structure. Consists of a sequence of nodes, each node containing data and a pointer to the next node. In Java, there are two types of linked lists, namely singly linked lists and doubly linked lists. The following is a sample code that demonstrates how to create, insert and delete linked list nodes:

One-way linked list sample code:

class ListNode {
    int val;
    ListNode next;
    ListNode(int x) { val = x; }
}

// 创建链表
ListNode head = new ListNode(1);
ListNode second = new ListNode(2);
ListNode third = new ListNode(3);

// 连接链表节点
head.next = second;
second.next = third;

// 插入节点
ListNode newNode = new ListNode(4);
second.next = newNode;
newNode.next = third;

// 删除节点
second.next = third;

3. Stack (Stack):
   The stack is a linear data structure with a specific access strategy. It follows the principle of "Last In First Out (LIFO)", that is, the last element pushed into the stack is the first to be popped out of the stack. In Java, you can use the Stack class to implement a stack. The following is a sample code that demonstrates how to create, push and pop operations:

import java.util.Stack;

// 创建栈
Stack<String> stack = new Stack<>();

// 入栈
stack.push("Java");
stack.push("C++");
stack.push("Python");

// 出栈
String top = stack.pop();
System.out.println("出栈的元素是：" + top);

4. Queue (Queue):
   A queue is a linear data with a specific access strategy Structure, it follows the "First In First Out, FIFO" principle, that is, the element that is first enqueued is the first to be dequeued. In Java, you can use the Queue interface to implement a queue. The following is a sample code that demonstrates how to create, enqueue and dequeue operations:

import java.util.Queue;
import java.util.LinkedList;

// 创建队列
Queue<String> queue = new LinkedList<>();

// 入队
queue.add("Java");
queue.add("C++");
queue.add("Python");

// 出队
String front = queue.poll();
System.out.println("出队的元素是：" + front);

5. Hash table (HashMap):
   Hash table is a very commonly used Data structure, which is based on the mapping of key-value pairs. In Java, a hash table can be implemented using the HashMap class. The following is a sample code that demonstrates how to create, insert and find elements:

import java.util.HashMap;

// 创建哈希表
HashMap<String, Integer> hashMap = new HashMap<>();

// 插入元素
hashMap.put("Java", 1);
hashMap.put("C++", 2);
hashMap.put("Python", 3);

// 查找元素
int value = hashMap.get("Java");
System.out.println("Java对应的值是：" + value);

Summary:
This article introduces several data structures commonly used in Java, including arrays, linked lists, stacks, Queues and hash tables. Mastering the use of these data structures can greatly improve programming efficiency and quality. I hope this article can be helpful to readers in Java programming.

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