Core Java вопросы и ответы для интервью
Test your skills through the online practice test: Core Java Quiz Online Practice Test
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Вопрос 211. How are Observer and Observable used?
Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.
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Вопрос 212. How does Java handle integer overflows and underflows?
It uses those low order bytes of the result that can fit into the size of the type allowed by the operation.
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Вопрос 213. To what value is a variable of the String type automatically initialized?
The default value of an String type is null.
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Вопрос 214. What is the range of the short type?
The range of the short type is -(2^15) to 2^15 - 1.
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Вопрос 215. What is Downcasting ?
Downcasting is the casting from a general to a more specific type, i.e. casting down the hierarchy
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