// 偽代碼：CAS操作的邏輯分解
public boolean compareAndSwap(MemoryAddress addr, int expectedValue, int newValue) {
    // 1. 讀取內(nèi)存當(dāng)前值
    int currentValue = *addr; 
    // 2. 比較當(dāng)前值與預(yù)期值
    if (currentValue != expectedValue) {
        return false; // 值已被其他線程修改，操作失敗
    }
    // 3. 若值未變，執(zhí)行原子性更新
    *addr = newValue;
    return true;
}

private int count = 0;  
public synchronized void increment() {  
    count++;  
}  

AtomicInteger count = new AtomicInteger(0);  
public void increment() {  
    int oldValue, newValue;  
    do {  
        oldValue = count.get();  
        newValue = oldValue + 1;  
    } while (!count.compareAndSet(oldValue, newValue)); // CAS自旋  
}  

public class CASSpinLock {  
    private AtomicBoolean locked = new AtomicBoolean(false);  
    // 獲取鎖  
    public void lock() {  
        while (!locked.compareAndSet(false, true)) {  
            // 自旋：直到成功將locked從false改為true  
        }  
    }  
    // 釋放鎖  
    public void unlock() {  
        locked.set(false);  
    }  
}  

AtomicStampedReference<String> ref = new AtomicStampedReference<>("A", 0);  
// 線程1讀取值和版本號(hào)  
int stamp = ref.getStamp();  
String oldValue = ref.getReference();  
// 線程2修改值并更新版本號(hào)  
ref.compareAndSet("A", "B", stamp, stamp + 1);  
ref.compareAndSet("B", "A", stamp + 1, stamp + 2);  
// 線程1嘗試修改：雖然值還是A，但版本號(hào)已變，操作失?。? 
boolean success = ref.compareAndSet(oldValue, "C", stamp, stamp + 1);  

Callable<Integer> task = () -> {
    int sum = 0;
    for (int i = 1; i <= 100; i++) sum += i;
    return sum;
};
FutureTask<Integer> futureTask = new FutureTask<>(task);
new Thread(futureTask).start();
// 主線程獲取結(jié)果
System.out.println("計(jì)算結(jié)果：" + futureTask.get()); // 輸出 5050

class BankAccount {
    private final ReentrantLock lock = new ReentrantLock();
    private int balance = 100;
    void transfer(BankAccount target, int amount) {
        lock.lock();
        try {
            if (this.balance >= amount) {
                this.balance -= amount;
                target.balance += amount;
            }
        } finally {
            lock.unlock(); // 必須手動(dòng)釋放鎖
        }
    }
}

Semaphore semaphore = new Semaphore(3); // 3 個(gè)許可證
Runnable parkAction = () -> {
    try {
        semaphore.acquire(); // 獲取車(chē)位
        System.out.println(Thread.currentThread().getName() + " 停入車(chē)位");
        Thread.sleep(2000); // 停車(chē) 2 秒
    } catch (InterruptedException e) {
        e.printStackTrace();
    } finally {
        semaphore.release(); // 釋放車(chē)位
        System.out.println(Thread.currentThread().getName() + " 離開(kāi)車(chē)位");
    }
};
// 啟動(dòng) 5 輛車(chē)嘗試停車(chē)
for (int i = 0; i < 5; i++) {
    new Thread(parkAction).start();
}

public static void main(String[] args) {
        CountDownLatch latch = new CountDownLatch(3); // 需要等待 3 個(gè)任務(wù)
// 資源加載任務(wù)
        Runnable loadTask = () -> {
            try {
                Thread.sleep((long) (Math.random() * 2000));
                System.out.println(Thread.currentThread().getName() + " 加載完成");
                latch.countDown();
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        };
// 啟動(dòng) 3 個(gè)資源加載線程
        new Thread(loadTask, "地圖").start();
        new Thread(loadTask, "音效").start();
        new Thread(loadTask, "UI").start();
// 主線程等待所有資源加載完成
        try {
            latch.await();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        System.out.println("所有資源加載完成，開(kāi)始游戲！");
    }