Can two threads call two different synchronized instance methods of an Object?

Upasana | December 16, 2017 | 1 min read | 322 views

No. If a object has synchronized instance methods then the Object itself is used a lock object for controlling the synchronization. Therefore all other instance methods need to wait until previous method call is completed.

See the below sample code which demonstrate it very clearly. The Class Common has 2 methods called synchronizedMethod1() and synchronizedMethod2() MyThread class is calling both the methods.

public class Common {
  public synchronized void synchronizedMethod1() {
   System.out.println("synchronizedMethod1 called");
   try {
    Thread.sleep(1000);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
   System.out.println("synchronizedMethod1 done");
  }

  public synchronized void synchronizedMethod2() {
   System.out.println("synchronizedMethod1 called");
   try {
    Thread.sleep(1000);
   } catch (InterruptedException e) {
    e.printStackTrace();
   }
 }