Given the following code, which of the following expressions evaluates to false? class C1 {} class C2 extends C1 { } class C3 extends C2 { } class C4 extends C1 {} C1 c1 = new C1(); C2 c2 = new C2(); C3 c3 = new C3(); C4 c4 = new C4(); Group of answer choicesc1 instanceof C1c2 instanceof C1c3 instanceof C1c4 instanceof C2
Question
Given the following code, which of the following expressions evaluates to false? class C1 {} class C2 extends C1 { } class C3 extends C2 { } class C4 extends C1 {} C1 c1 = new C1(); C2 c2 = new C2(); C3 c3 = new C3(); C4 c4 = new C4(); Group of answer choicesc1 instanceof C1c2 instanceof C1c3 instanceof C1c4 instanceof C2
Solution
The expression that evaluates to false is c4 instanceof C2.
Here's why:
c1 instanceof C1is true because c1 is an instance of C1.c2 instanceof C1is true because C2 extends C1, so an instance of C2 is also considered an instance of C1.c3 instanceof C1is true because C3 extends C2, which extends C1, so an instance of C3 is also considered an instance of C1.c4 instanceof C2is false because C4 extends C1 directly and does not have any relationship with C2. Therefore, an instance of C4 is not considered an instance of C2.
Similar Questions
Which statements are most accurate regarding the following classes? class A { private int i; protected int j; } class B extends A { private int k; protected int m; } Group of answer choicesAn object of B contains data fields i, j, k, m.An object of B contains data fields j, k, m.An object of B contains data fields j, m.An object of B contains data fields k, m.
Which of the following statements is FALSE?Group of answer choicesA subclass is a subtype of its superclass.A subclass is usually extended to contain more functions and more detailed information than its superclass."class A extends B" means A is a subclass of B."class A extends B" means B is a subclass of A.
Which of the following statements is false? Group of answer choicesYou can always pass an instance of a subclass to a parameter of its superclass type. This feature is known as polymorphism.The compiler finds a matching method according to parameter type, number of parameters, and order of the parameters at compile time.A method may be implemented in several subclasses. The Java Virtual Machine dynamically binds the implementation of the method at runtime.Dynamic binding can apply to static methods.Dynamic binding can apply to instance methods.
Which statements are most accurate regarding the following classes? class A { private int i; protected int j; } class B extends A { private int k; protected int m; // some methods omitted } Group of answer choicesIn the class B, an instance method can only access i, j, k, m.In the class B, an instance method can only access j, k, m.n the class B, an instance method can only access j, m.In the class B, an instance method can only access k, m.
Which of the following statements regarding instance variables are false? You can select more than one statement.Group of answer choicesInstance variables are defined inside a method.Instance variables maintain the "state" of an object.An instance variable is unique to an object.An instance variable is unique to a class.An attribute of a class can be an instance variable.
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.