java - synchronizedList access by multiple threads -

i have basic question synchronizedlist.

lets have synchronizedlist -

list synclist = collections.synchronizedlist(new arraylist<>()) 

now scenario thread trying access add() api , thread b trying access remove() api of synchronizedlist. both thread able access both(add , remove) api @ same time.

i believe threads should not access api(add() , remove()) same time. please correct me if wrong.

will both thread able access both(add , remove) api @ same time.

the answer no.

if chance @ collections.synchronizedlist(list) source code, see that, method creating instance of static inner class named synchronizedlist or synchronizedrandomaccesslist, depending on type of list send argument.

now both these static inner class extend common class called synchronizedcollection, maintains mutex object, on method operations synchronize on

this mutex object assigned this, means that, mutex object same returned instance.

since add() , remove() methods performed under

synchronized(mutex) {  } 

block, thread executes add (and aquires lock on mutex), not allow another thread execute remove (by aquiring lock on same mutex), since former has already locked mutex. latter thread wait until lock obtained former thread on mutex gets released.

so, yes add() , remove() mutually exclusive