Multi-Threading : Acquiring a lock on null reference

The lock is acquired on object (not on reference ) .

We can not acquire the lock on null object or reference pointing to null object.


public class LockOnNull {

private static Object lock = null;

public static void main(String ar[]) {

private static void sayHello() {
synchronized (lock) {
System.out.println(“Inside the synchronized block”);

Output –¬† NullPointerException¬†

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