Question

I have a quick question about Java synchronization.

Please assume the following code:

public class Test {
    private String address;
    private int age;

    public synchronized setAddress(String a) {
        address = a;
    }

    public synchronized setAge(int a) {
        age = a;
    }

    public synchronized void start() {
          ...

          listener = new Thread(new Runnable(){
              public void run() {
                      ...
                  setAge(10);
                      ...

                  synchronized(Test.this) {
                      address = null;
                  }
              }
          }
    }
}

I am a little bit unsure about Java synchronization when synchronized method or synchronized block is called inside another thread.

Assume the thread running class Test as A, and
the listener thread B.

Then if I execute the code above, does it guarantee that synchronized method calls and synchronized block are synchronized with the A (the thread running Test class) ?

Thank you for reading.

Answer 1

No,

The synchronized methods are locking the Test instance, while the synchronized block is locking the Test class object.

See Java synchronized static methods: lock on object or class and Java Synchronized Block for .class