Fill in the blank.

41. AWT stands for _______________________________________________________________.

42. A Java programmer must __________________ or _____________________ all checked exceptions.

43. The _________________ clause is used to mark a block of code to be executed whether or not an exception occurred.

44. The _________________ access specifier is used to group otherwise unrelated classes.

45. If a class implements an interface, that class must also define all _____________________ specified in the interface.

46. ____________________ are helper classes which implement do-nothing versions of all methods required by an interface.

47. A nested class is also considered ________________ unless it has been declared _________________.

48. A listener registered with two sources may determine which one generated an event by calling the __________________ method of the ______________________.

49. A stream object that can attach to something is known as a _____________________ stream; a stream object that can change the data passing through it is known as a _____________________stream.

50. All input streams descend from either ___________________ or ___________________________.