Java设计模式之单例模式的实现

public class Singleton {
    private static volatile Singleton instance;
    
    private Singleton() {
        // 私有构造函数，防止外部实例化对象
    }
    
    public static Singleton getInstance() {
        if (instance == null) {
            synchronized (Singleton.class) {
                if (instance == null) {
                    instance = new Singleton();
                }
            }
        }
        return instance;
    }
    
    // 其他业务逻辑代码...
}

public class Main {
    public static void main(String[] args) {
        Singleton singleton1 = Singleton.getInstance();
        Singleton singleton2 = Singleton.getInstance();
        
        System.out.println(singleton1 == singleton2);  // 输出结果为 true，说明获取的实例是同一个对象
    }
}

Java多线程编程中的同步问题解决

public class SynchronizedExample {
    private int count = 0;
    
    public synchronized void increment() {
        count++;
    }
    
    public static void main(String[] args) {
        SynchronizedExample example = new SynchronizedExample();
        
        Thread thread1 = new Thread(() -> {
            for (int i = 0; i< 1000; i++) {
                example.increment();
            }
        });
        
        Thread thread2 = new Thread(() -> {
            for (int i = 0; i< 1000; i++) {
                example.increment();
            }
        });
        
        thread1.start();
        thread2.start();
        
        try {
            thread1.join();
            thread2.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        
        System.out.println("Count: " + example.count);  // 输出结果为 2000，说明同步成功
    }
}

Java异常处理机制及最佳实践

public class ExceptionHandling {
    public static void main(String[] args) {
        try {
            int num1 = Integer.parseInt(args[0]);
            int num2 = Integer.parseInt(args[1]);

            int result = divide(num1, num2);
            System.out.println("Result: " + result);
        } catch (NumberFormatException e) {
            System.out.println("Invalid input: " + e.getMessage());
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Please provide two numbers as input.");
        } catch (ArithmeticException e) {
            System.out.println("Cannot divide by zero.");
        }
    }

    public static int divide(int num1, int num2) {
        return num1 / num2;
    }
}

Java常用数据结构之链表的实现

public class ListNode {
    private int val;
    private ListNode next;
    
    public ListNode(int val) {
        this.val = val;
    }
    
    public int getVal() {
        return val;
    }
    
    public ListNode getNext() {
        return next;
    }
    
    public void setNext(ListNode next) {
        this.next = next;
    }
}

public class LinkedList {
    private ListNode head;
    
    public LinkedList() {
        head = null;
    }
    
    public void insert(int val) {
        ListNode newNode = new ListNode(val);
        
        if (head == null) {
            head = newNode;
        } else {
            ListNode temp = head;
            while (temp.getNext() != null) {
                temp = temp.getNext();
            }
            temp.setNext(newNode);
        }
    }
    
    public void display() {
        ListNode temp = head;
        while (temp != null) {
            System.out.print(temp.getVal() + " ");
            temp = temp.getNext();
        }
    }
    
    public static void main(String[] args) {
        LinkedList list = new LinkedList();
        list.insert(1);
        list.insert(2);
        list.insert(3);
        
        list.display();  // 输出结果为 1 2 3
    }
}