java synchronized object lock

In Java, you can use the synchronized keyword to synchronize access to an object and ensure that only one thread can execute a particular block of code at a time. This is known as obtaining a lock on the object.

Here is an example of how to use the synchronized keyword to obtain a lock on an object:

class MyClass {
    private final Object lock = new Object();
    
    public void doSomething() {
        synchronized (lock) {
            // code that needs to be synchronized goes here
        }
    }
}

In this example, the lock field is an object that is used as a lock. The doSomething method synchronizes on the lock object using the synchronized keyword. This ensures that only one thread can execute the code inside the synchronized block at a time.

You can also use the synchronized keyword to synchronize on the this object, which represents the current instance of the class.

For example:

class MyClass {
    public void doSomething() {
        synchronized (this) {
            // code that needs to be synchronized goes here
        }
    }
}

In this example, the doSomething method synchronizes on the this object, which ensures that only one thread can execute the code inside the synchronized block at a time.

It is important to note that the synchronized keyword can have a negative impact on performance, as it can cause contention and lock contention among threads. Therefore, it is generally recommended to use the synchronized keyword only when it is necessary to ensure thread safety, and to minimize the amount of code that is synchronized.