What are the applications of Synchronized?

“Synchronized is a keyword in Java that is used to ensure thread synchronization, applying it in various scenarios to guarantee the order of access and consistency of data among multiple threads.”

Here are some common usage methods of Synchronized:

1. Synchronized instance method: By adding the synchronized keyword in the method declaration, it allows only one thread to access the method at a time. For example:

public synchronized void synchronizedMethod() {
    // 同步代码块
}

1. Synchronizing instance objects: By using the synchronized keyword within a code block and passing the instance object as the lock object, only one thread can enter the synchronized code block at a time. For example:

public void synchronizedBlock() {
    synchronized (this) {
        // 同步代码块
    }
}

1. Synchronized static methods: By adding the synchronized keyword in the declaration of a static method, only one thread can access that method at a time. For example:

public static synchronized void synchronizedStaticMethod() {
    // 同步代码块
}

1. Synchronization of class objects: By using the synchronized keyword in a code block and passing the class object as the lock object, only one thread can enter the synchronized code block at a time. For example:

public void synchronizedBlock() {
    synchronized (ClassName.class) {
        // 同步代码块
    }
}

It’s important to note that using the synchronized keyword can lead to thread blocking and waiting, so it’s necessary to design and use it appropriately based on specific situations. Additionally, Java also offers other thread synchronization mechanisms such as the Lock and Condition interfaces, allowing developers to choose the most suitable synchronization method based on their needs.