Which are incorrect class declarations? : Questions « Object Oriented « SCJP






  1. SCJP
  2. Object Oriented
  3. Questions
A.   public synchronized class FastClass extends Thread
B.   private protected class FastClass
C.   public abstract class FastClass
D.   class FastClass extends Thread








6.13.Questions
6.13.1.Is it legal enums: enum Animals {int age;LION, TIGER, DOG;}
6.13.2.Answer: enum and underline value
6.13.3.Is it legal enums:enum Animals {LION, TIGER, DOG;int weight;}
6.13.4.Answer: enum definition in a class
6.13.5.Is it legal enums?
6.13.6.Answer: enum, underline value and constructor
6.13.7.Is it legal enums(enum and constructor)?
6.13.8.Answer: enum and constructor
6.13.9.Which of the following may override a method whose signature is void a(float f)?
6.13.10.Answer: method signature and override
6.13.11.An enum definition should declare that it extends java.lang.Enum(True/False).
6.13.12.Answer: enum definition and java.lang.Enum
6.13.13.An enum may be subclassed(True/False).
6.13.14.Answer: enum and subclassing
6.13.15.An enum may contain public method definitions(True/False).
6.13.16.Answer: enum and methods
6.13.17.An enum may contain private data.
6.13.18.Answer: enum and data
6.13.19.An enum definition may contain the main() method of an application(True/False).
6.13.20.Answer: enum and main method
6.13.21.You can call an enum's toString() method(True/False).
6.13.22.Answer: enum and toString() method
6.13.23.You can call an enum's wait() method(True/False).
6.13.24.Answer: enum and wait method
6.13.25.You can call an enum's notify() method(True/False).
6.13.26.Answer: enum and notify method
6.13.27.Which are incorrect class declarations?
6.13.28.Answer: class declaration
6.13.29.What is the output from the following code
6.13.30.Answer: final variable
6.13.31.What is wrong with the following code?
6.13.32.Answer: local variable
6.13.33.Which of the following constructor signatures must exist in the Demo class for DerivedDemo to compile correctly?
6.13.34.Answer: constructor and class hierarchy
6.13.35.Which is a correct class based on the following interface?
6.13.36.Answer: class and interface implementation
6.13.37.What is the result when trying to compile and run the following code(class definition hierarchy)?
6.13.38.Answer: class definition hierarchy
6.13.39.What is the result when trying to compile and run the following code(final and class hierarchy)?
6.13.40.Answer: final and class hierarchy
6.13.41.Cohesion is to hide implementation details(True/False)
6.13.42.Answer: cohesion
6.13.43.Cohesion is to make sure that classes know about other classes only through their APIs(True/False)
6.13.44.Answer: cohesion(2)
6.13.45.Cohesion is to make sure that a class is designed with a single, well-focused purpose(True/False)
6.13.46.Answer: cohesion(3)
6.13.47.Cohesion is to allow a single object to be seen as having many types(True/False)
6.13.48.Answer: cohesion(4)
6.13.49.Will the following code compile(class hierarchy)?
6.13.50.Answer: class hierarchy
6.13.51.What is the result when trying to compile and run the following code(class hierarchy and override)?
6.13.52.Answer: class hierarchy and override
6.13.53.What is the result(method overload)?
6.13.54.Answer: method overload
6.13.55.What is the result(polymorphism and static method)?
6.13.56.Answer: polymorphism and static method
6.13.57.What is the result(three level class hierarchy)?
6.13.58.Answer: three level class hierarchy
6.13.59.What is the result(constructors and superclass)?
6.13.60.Answer: constructors and superclass
6.13.61.What is the result(Polymorphism and instance methods)?
6.13.62.Answer: Polymorphism and instance methods
6.13.63.What is the result(overloaded and var-args methods)?
6.13.64.Answer: overloaded and var-args methods