??????????????????????????????????????????????? ??increment??????decrement?????????before??after????????????????????????????????????

??????????????increment()??decrement()??????synchronized ???κ????????иó????????????￡?

????before increment?? c = 0
????after increment?? c = 1
????before increment?? c = 1
????after increment?? c = 2
????before decrement?? c = 2
????after decrement?? c = 1
????before increment?? c = 1
????after increment?? c = 2
????before decrement?? c = 2
????after decrement?? c = 1
????before decrement?? c = 1
????after decrement?? c = 0
????before decrement?? c = 0
????after decrement?? c = -1
????before decrement?? c = -1
????after decrement?? c = -2
????before increment?? c = -2
????after increment?? c = -1
????before decrement?? c = -1
????after decrement?? c = -2
????before decrement?? c = -2
????after decrement?? c = -3
????before decrement?? c = -3
????after decrement?? c = -4
????before decrement?? c = -4
????after decrement?? c = -5
????before increment?? c = -5
????after increment?? c = -4
????before decrement?? c = -4
????after decrement?? c = -5
????before increment?? c = -5
????after increment?? c = -4
????before increment?? c = -4
????after increment?? c = -3
????before increment?? c = -3
????after increment?? c = -2
????before increment?? c = -2
????after increment?? c = -1
????before increment?? c = -1
????after increment?? c = 0

???????????????????????synchronized???η????????????????ε?increment??decrement????????г??????????????????10?ε?increment()??decrement ()?н???????????synchronized????????????

???????????????????????????п??????synchronized?????????????

????????????????????????????????Counter??????????????????????????????????Ч???????????????????????????????????