Can you explain the purpose and working principle of the synchronized keyword in Java?

The synchronized keyword in Java is used to control access to shared resources in a multithreaded environment. It ensures that only one thread can execute a specific block of code or method at a time, preventing race conditions and ensuring data integrity.

Working principle:

• When a thread enters a synchronized block or method, it acquires the monitor (lock) of the object.
• Other threads attempting to enter the same synchronized block or method on the same object will wait until the monitor is released.
• After exiting the synchronized block, the monitor is released, and the next waiting thread can enter.

Example:

public class Counter {
    private int count = 0;

    public synchronized void increment() {
        count++;
    }

    public int getCount() {
        return count;
    }
}

Here, the increment method is synchronized to prevent multiple threads from changing the count variable simultaneously.