Abstraction

Quiz Guidelines

 

Multiple Choice Question

QID: 
507

What, if anything, is wrong with the following code?

abstract class TestClass{
transient int j;
synchronized int k;
final void TestClass(){}
static void f(){
k = j++;
}
}

Select 2 options

A. The class TestClass cannot be declared abstract.
B. The variable j cannot be declared transient.
C. The variable k cannot be declared synchronized.
D. The constructor TestClass( ) cannot be declared final.
E. The method f( ) cannot be declared static.

Multiple Choice Question

QID: 
506

Which one of the following class definitions is/are a legal definition of a class that cannot be instantiated?

class Automobile{
abstract void honk(); //(1)
}
abstract class Automobile{
void honk(); //(2)
}
abstract class Automobile{
void honk(){}; //(3)
}
abstract class Automobile{
abstract void honk(){} //(4)
}
abstract class Automobile{
abstract void honk(); //(5)
}

Select 2 options

A. 1
B. 2
C. 3
D. 4
E. 5

Multiple Choice Question

QID: 
505

A java source file contains the following code:

interface I {
int getI(int a, int b);
}
interface J{
int getJ(int a, int b, int c);
}
abstract class MyIJ implements J , I { }
class MyI{
int getI(int x, int y){ return x+y; }
}
interface K extends J{
int getJ(int a, int b, int c, int d);
}

Identify the correct statements:

Select 1 option

A. It will fail to compile because of MyIJ
B. It will fail to compile because of MyIJ and K
C. It will fail to compile because of K
D. It will fail to compile because of MyI and K
E. It will fail to compile because of MyIJ, K, and MyI
F. It will compile without any error.

Multiple Choice Question

QID: 
504

Which of the following statements are acceptable?

Select 4 options

A. Object o = new java.io.File("a.txt");  (Assume that java.io.File is a valid class.)
B. Boolean bool = false;
C. char ch = 10;
D. Thread t = new Runnable() ;(Assume that Runnable is a valid interface.) 
E. Runnable r = new Thread();  (Assume that Thread is a class that implements Runnable interface)

Multiple Choice Question

QID: 
503

Which one of these is a proper definition of a class TestClass that cannot be subclassed?

Select 1 option

A. final class TestClass { }
B. abstract class TestClass { }
C. native class TestClass { }
D. static class TestClass { }
E. private class TestClass { }

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