Core Java اسئلة واجوبة المقابلات
Test your skills through the online practice test: Core Java Quiz Online Practice Test
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سؤال 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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سؤال 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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سؤال 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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سؤال 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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سؤال 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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الاكثر فائدة حسب تقييم المستخدمين:
- How could Java classes direct program messages to the system console, but error messages, say to a file?
- What are the differences between an interface and an abstract class?
- Why would you use a synchronized block vs. synchronized method?
- How can you force garbage collection?
- What are the differences between the methods sleep() and wait()?