Question

ceinterface Interface1 Abstract eeinterfaces Interface ceinterface Interface Classi Class Class3 Classe Interfacet obji - new class3(); Abstracti obj2 = new Class1(); object obj3 = new Class2); class3 obj4 new Class4(); a) [1 pt) Is obji instanceof Interface? O True O False O True O False b) f1 pt) Is obj3 instanceof Interface1? c) (1 pt] Is obj4 instanceof Interfaces ? O True O False d) (1 pt) Is obj2 instanceof Interface1? O True False e) (2 pts each] State the execution result (compile error, runtime error - ClassCastException, or no problem) for the following statements and explain the reason for the error cases. Each case is independent from each other. Suppose the method a Method is defined in the Class4. i) obj1.amethod()) ii) Interfaces objs = obj2; iii) ((Class)obj)), amethod(); iv) ((Class4)obj4). aMethod(); +) (4 pts] Suppose that method "void m2(){};" is in Abstract. Which classes have to implement it?

Answer 1

a)True,obj1 can access all methods in interface 2 because interface2 implemented in class3

b)True,obj3 can access properties of class2 and class2 extended the properties of class3 and it has implemented the interface1.

c) False,class4 extended the properties of class3 only, but class3 implemented interface1, interface2 only. No way to reach of interface3

d) True, class1 extended the properties of class2 and class2 has has all access over interfaces and classes because it extended the class3 and implemented interface3

e)i. Compiler error. because class4 extended the class3 which is interface because it implemented the interface2 so now class4 too becomes a interface thus it can't define its methods only declare the methods in interface right!

ii) gives compiler error with abstract class can't be initiated.

iii) compiler error. Because object already defined with other class.so it can't be converted. Gives an error

iv) no error, because obj4 is already assigned to class4 and there is no class conversion in code that's why don't give error.

f)the method m2() has to be defined in class1 because it extended the abstract class so that class abstract method should be defined in class 1