Answer: class hierarchy and override : Questions « Object Oriented « SCJP






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Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
  The method sniff() is undefined for the type Dog

  at MainClass.go(MainClass.java:25)
  at MainClass.main(MainClass.java:19)


Class Dog doesn t have a sniff method.








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