MileStone 1 - Java - MCQS

Which one of the following statement is false?

• A subclass must override all the methods of the superclass

• it is possible for a subclass to define a method with the same name and parameters as a method defined by the superclass

• Aggregation defines a has-a relationship between a superclass and its subclasses

• Inheritance defines a is-a relationship between a superclass and its subclass

Given the following

class A{

public void baz(){

System.out.println(“A”);

}

}

public class B extends A{

public static void main(String [] args){

A a = new b();

a.baz();

}

public void baz(){

System.out.println(“B”);

}

}

What is the result?

• A

• B

• Compilation fails

• An exception is thrown at runtime

Given the following

class Over{

int doStuff(int a, float b){

return 7;

}

}

class Over2 extends Over{

//insert code here

}

Which method, if inserted at line 8, will not compile?

• public int doStuff(int x, float y) {return 4;}

• protected int doStuff(int x, float y) {return 4;}

• private int doStuff(int x, float y) {return 4;}

• private int doStuff(int x, double y) {return 4;}

Given the below mentioned code and the command-line invocation as,

Java CommandArgs 1 2 3 4

public class CommandArgs {

public static void main(Strings[] args) {

String s1 = args[1];

String s2 = args[2];

String s3 = args[3];

String s4 = args[4];

System.out.print(“args[2] = “ +s2);

}

}

What is the result?

• args[2] = 2

• args[2] = 3

• args[2] = 1

• An exception is thrown at runtime

5. Which one of the following statements is true?

• an abstract class can be instantiated

• An abstract class is implicitly final

• An abstract class can declare non-abstract methods

• An abstract class can not extend a concrete class

Which statement is true about interfaces?

• a. Interfaces allow multiple implementation inheritance

• b. Interfaces can extend any number of other interfaces

• c. Members of an interface are never static

• d. Members of an interface can always be declared static

A class Car and its subclass Yugo both have a method run() which was written by the programmer as part of the class definition. If junker refers to an object of type Yugo, what will the following code do?

junker.run();

• The run() method defined in Yugo will be called

• The run() method defined in Car will be called

• The compiler will complain that run() has been defined twice

• Overloading will be used to pick which run() is called

Which of the following will declare an array and initialize it?

• Array a = new Array(5)

• int array[] = new int[5];

• int a[] = new int(5)

• int [5] array;

Which of the statements are true?

• finally block gets executed only when there are exceptions

• finally gets always executed irrespective of the flow in try catch blocks

• finally block can be present only when a catch block is present

• finally block gets executed only when there are no exceptions

What is an abstract method?

• An abstract method is any method in an abstract class

• An abstract method is a method which cannot be inherited

• An abstract method is one without a body that is declared with the reserved word abstract

• An abstract method is a method in the child class that overrides a parent method