Description: In paragraph (3) small problems in the Clock class because only new entrants to achieve a Soundable interface stopsound () and playsound () method, and increaseVolume () and decreaseVolume () method not implemented, so it is essentially an abstract class The abstract class can not be instantiated, thus resulting in a compile error. But according to common sense, is indeed a ticking alarm clock can not increase or decrease, then how to solve this problem? Now add in the Clock class {} with the following two methods to achieve an empty method body, and then compile and run the program to see what changes.
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InterfaceTest\Clock.class
.............\InterfaceTest.class
.............\InterfaceTest.java
.............\Mobilephone.class
.............\People.class
.............\Radio.class
.............\Soundable.class
.............\Walkman.class
InterfaceTest
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