Java设计一个顺序表，类成员函数包括插入，删除，取数据元素，是否空，并设计测试主函数验证类成员函数正确性

在Java中，我们可以设计一个名为`LinkedList`的简单顺序表类，它包含插入、删除、获取元素以及检查是否为空的功能。下面是一个示例实现：

import java.util.LinkedList;

class LinkedListNode {
    int data;
    LinkedListNode next;

    public LinkedListNode(int data) {
        this.data = data;
        this.next = null;
    }
}

public class LinkedList {
    private LinkedListNode head;

    // 插入元素
    public void insertAtEnd(int data) {
        LinkedListNode newNode = new LinkedListNode(data);
        if (head == null) {
            head = newNode;
        } else {
            LinkedListNode temp = head;
            while (temp.next != null) {
                temp = temp.next;
            }
            temp.next = newNode;
        }
    }

    // 删除元素
    public boolean deleteElement(int key) {
        if (head == null) {
            return false;
        }
        if (head.data == key) {
            head = head.next;
            return true;
        }
        LinkedListNode prev = head;
        LinkedListNode curr = head.next;
        while (curr != null) {
            if (curr.data == key) {
                prev.next = curr.next;
                return true;
            }
            prev = curr;
            curr = curr.next;
        }
        return false;
    }

    // 取数据元素
    public int get(int index) {
        if (index < 0 || index >= size()) {
            throw new IllegalArgumentException("Index out of range");
        }
        LinkedListNode node = head;
        for (int i = 0; i < index; i++) {
            node = node.next;
        }
        return node.data;
    }

    // 检查是否为空
    public boolean isEmpty() {
        return head == null;
    }

    // 计算列表长度
    private int size() {
        int count = 0;
        LinkedListNode temp = head;
        while (temp != null) {
            count++;
            temp = temp.next;
        }
        return count;
    }

    // 主函数进行测试
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.insertAtEnd(1);
        list.insertAtEnd(2);
        list.insertAtEnd(3);

        System.out.println("Is the list empty? " + list.isEmpty()); // 应该打印false

        System.out.println("Get element at index 0: " + list.get(0)); // 应该打印1
        System.out.println("Delete element 2: " + list.deleteElement(2)); // 应该打印true
        System.out.println("After deletion, is element 2 still present? " + list.deleteElement(2)); // 应该打印false

        list.printList(); // 打印剩余的元素
    }

    // 打印链表
    private void printList() {
        LinkedListNode temp = head;
        while (temp != null) {
            System.out.print(temp.data + " -> ");
            temp = temp.next;
        }
        System.out.println("null");
    }
}

在`main`函数中，我们测试了插入、删除、获取和判断空的操作。你可以运行这个代码来看看是否实现了预期的行为。