Java MCQ Quiz ( Part - 9 ) | infoStud blogs

Following quiz provides Multiple Choice Questions (MCQs) related to Core Java. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz

1. Can an abstract class define both abstract methods and non-abstract methods?

1. Yes – the subclass inherits both.
2. No – she must have either one or the other.
3. No – it can only have abstract methods.
4. Yes – but the abstract methods are not inherited from the subclass.

2. What does polymorphism mean in Java?

1. If a program uses several different types of objects, each with its own variable.
2. If a single superclass has multiple subclasses.
3. When a single variable is used for several different but related object types in different parts of the program.
4. If a class has different methods with the same name but different parameter types.

3. What is the advantage of polymorphism?

1. The same programming logic can be applied to multiple related object types.
2. Variables can be reused to save memory.
3. Constructing new objects from old objects of a similar type saves time.
4. Polymorphism is a dangerous aspect of heredity and should be avoided.

4. What is the signature of a method?

1. The signature of a method is the name of a method and the type of its return value.
2. The signature of a method is the name of the method and the names of its parameters.
3.The signature of a method is the name of the method and the data types of its parameters.
4. The signature of a method is the name of the method, its parameter list, and its return type.

5. What must a non-abstract subclass do with an abstract method of its superclass?

1. A subclass must override an inherited abstract method by defining a method with the same signature and return type:
2. A subclass must define an additional method that is similar to the inherited method in that it defines a method with the same signature but a different return type.)
3. A subclass can not define a method with the same signature as it already has an abstract method of the superclass.
4. A non-abstract subclass can not define an abstract method with the same signature and return type as the superclass’s abstract method.

6. Assume that there is three classes Computer, AppleComputerand IBMComputer. What does the relationship between these classes look like?

1. Computer, AppleComputerand IBMComputerare sibling classes.
2. IBMComputeris the superclass, AppleComputerand Computerare subclasses of IBMComputer.
3. Computeris the superclass, AppleComputerand IBMComputerare subclasses of Computer.
4. Computeris a superclass, AppleComputeris a subclass of Computerand IBMComputeris a subclass of AppleComputer.

7. What must be true if a subclass of an abstract superclass does not override the abstract methods of the superclass?

1. The subclass itself must be declared abstract.
2. Subclasses are automatically non-abstract, so that’s OK.
3. The superclass is a mistake.
4. That’s always a mistake.

8. How many objects of a given class can be in a program?

1.As many as the program needs.
2. One per defined class.
3. One per constructor definition.
4. One per main()method.

9. What is the name of the class that is the ancestor of each class in Java?

1. Object
2. Class
3. root
4. Java

10.What is an abstract method?

1. An abstract method is any method in an abstract class.
2. An abstract method is a method that can not be inherited.
3. An abstract method is a bodyless method abstractdeclared with the reserved word .
4. An abstract method is a method in the subclass that overrides the method of a superclass.