Basic Concept of OOP - Quiz

Which one of these lists contains only Java programming language keywords?

Aclass, if, void, long, Int, continue
Bgoto, instanceof, native, finally, default, throws
Ctry, virtual, throw, final, volatile, transient
D strictfp, constant, super, implements, do

Which three are legal array declarations?

int [] myScores [];

char [] myChars;

int [6] myScores;

Dog myDogs [];

Dog myDogs [7];

A1, 2, 4
B2, 4, 5
C2, 3, 4
DAll are correct.

Which three are valid declarations of a char?

char c1 = 064770;

char c2 = 'face';

char c3 = 0xbeef;

char c4 = \u0022;

char c5 = '\iface';

char c6 = '\uface';

A1, 2, 4
B1, 3, 6
C3, 5
D5 only

What is the numerical range of a char?

A-128 to 127
B-(2¹⁵⁾ to (2¹⁵) - 1
C0 to 32767
D0 to 65535

public class F0091 
{    
    public void main( String[] args ) 
    {  
        System.out.println( "Hello" + args[0] ); 
    } 
}

What will be the output of the program, if this code is executed with the command line: > java F0091 world

AHello
BHello Foo91
CHello world
DThe code does not run.

In the given program, how many lines of output will be produced?


public class Test 
{
    public static void main(String [] args) 
    {
    int [] [] [] x = new int [3] [] [];
    int i, j;
    x[0] = new int[4][];
    x[1] = new int[2][];
    x[2] = new int[5][];
    for (i = 0; i < x.length; i++)
    {
        for (j = 0; j < x[i].length; j++) 
        {
            x[i][j] = new int [i + j + 1];
            System.out.println("size = " + x[i][j].length);
        }
    }
    }
}

Which of the following is known as natural language?

A3 GL
B4 GL
CBoth a and b
D5 GL

Which of the following is a pillar of Object-Oriented programming?

AVariable
BPolymorphism
CSuper class
DSub class

Which of the following is called java compiler?

Ajavab
Bjavac
CjavaCompiler
Djavacompile

Question: Which of the following is not an object-oriented programming language?

A C++
B Simula
C BASIC
D Java

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Basic Concept of OOP - Quiz

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Q: Which one of these lists contains only Java programming language keywords?

A. class, if, void, long, Int, continue
B. goto, instanceof, native, finally, default, throws
C. try, virtual, throw, final, volatile, transient
D. strictfp, constant, super, implements, do

Correct Option: B
Remarks:

Explanation:

All the words in option B are among the 49 Java keywords. Although goto reserved as a keyword in Java, goto is not used and has no function.

Option A is wrong because the keyword for the primitive int starts with a lowercase i.

Option C is wrong because "virtual" is a keyword in C++, but not Java.

Option D is wrong because "constant" is not a keyword. Constants in Java are marked static and final.

Option E is wrong because "include" is a keyword in C, but not in Java.

Q: Which three are legal array declarations?

int [] myScores [];

char [] myChars;

int [6] myScores;

Dog myDogs [];

Dog myDogs [7];

A. 1, 2, 4
B. 2, 4, 5
C. 2, 3, 4
D. All are correct.

Correct Option: A
Remarks:

Explanation:

(1), (2), and (4) are legal array declarations. With an array declaration, you can place the brackets to the right or left of the identifier. Option A looks strange, but it's perfectly legal to split the brackets in a multidimensional array, and place them on both sides of the identifier. Although coding this way would only annoy your fellow programmers, for the exam, you need to know it's legal.

(3) and (5) are wrong because you can't declare an array with a size. The size is only needed when the array is actually instantiated (and the JVM needs to know how much space to allocate for the array, based on the type of array and the size).

Q: Which three are valid declarations of a char?

char c1 = 064770;

char c2 = 'face';

char c3 = 0xbeef;

char c4 = \u0022;

char c5 = '\iface';

char c6 = '\uface';

A. 1, 2, 4
B. 1, 3, 6
C. 3, 5
D. 5 only

Correct Option: B
Remarks:

Explanation:

(1), (3), and (6) are correct. char c1 = 064770; is an octal representation of the integer value 27128, which is legal because it fits into an unsigned 16-bit integer. char c3 = 0xbeef; is a hexadecimal representation of the integer value 48879, which fits into an unsigned 16-bit integer. char c6 = '\uface'; is a Unicode representation of a character.

char c2 = 'face'; is wrong because you can't put more than one character in a char literal. The only other acceptable char literal that can go between single quotes is a Unicode value, and Unicode literals must always start with a '\u'.

char c4 = \u0022; is wrong because the single quotes are missing.

char c5 = '\iface'; is wrong because it appears to be a Unicode representation (notice the backslash), but starts with '\i' rather than '\u'.

Q: What is the numerical range of a char?

A. -128 to 127
B. -(2¹⁵⁾ to (2¹⁵) - 1
C. 0 to 32767
D. 0 to 65535

Correct Option: D
Remarks:

Explanation:

A char is really a 16-bit integer behind the scenes, so it supports 2¹⁶ (from 0 to 65535) values.

public class F0091 
{    
    public void main( String[] args ) 
    {  
        System.out.println( "Hello" + args[0] ); 
    } 
}

What will be the output of the program, if this code is executed with the command line: > java F0091 world

A. Hello
B. Hello Foo91
C. Hello world
D. The code does not run.

Correct Option: D
Remarks:

Explanation:

Option D is correct. A runtime error will occur owning to the main method of the code fragment not being declared static:

Exception in thread "main" java.lang.NoSuchMethodError: main

The Java Language Specification clearly states: "The main method must be declared public, static, and void. It must accept a single argument that is an array of strings."

Q: In the given program, how many lines of output will be produced?


public class Test 
{
    public static void main(String [] args) 
    {
    int [] [] [] x = new int [3] [] [];
    int i, j;
    x[0] = new int[4][];
    x[1] = new int[2][];
    x[2] = new int[5][];
    for (i = 0; i < x.length; i++)
    {
        for (j = 0; j < x[i].length; j++) 
        {
            x[i][j] = new int [i + j + 1];
            System.out.println("size = " + x[i][j].length);
        }
    }
    }
}

A. 7
B. 9
C. 11
D. 13

Correct Option: C
Remarks:

Explanation:

The loops use the array sizes (length).

It produces 11 lines of output as given below.

D:\Java>javac Test.java

D:\Java>java Test
size = 1
size = 2
size = 3
size = 4
size = 2
size = 3
size = 3
size = 4
size = 5
size = 6
size = 7

Therefore, 11 is the answer.

Q: Which of the following is known as natural language?

A. 3 GL
B. 4 GL
C. Both a and b
D. 5 GL

Correct Option: D
Remarks:

Explanation: 5 GL

Q: Which of the following is a pillar of Object-Oriented programming?

A. Variable
B. Polymorphism
C. Super class
D. Sub class

Correct Option: B
Remarks:

Explanation:

The correct answer is: Polymorphism

Polymorphism is one of the four fundamental pillars of Object-Oriented Programming (OOP). The other three pillars are:

Encapsulation: Involves bundling data and methods that operate on the data into a single unit (class) and controlling access to the internal details of the object.
Inheritance: Allows a new class (subclass or derived class) to inherit attributes and methods from an existing class (superclass or base class), promoting code reuse.
Polymorphism: Enables objects of different types to be treated as objects of a common type. This can occur at compile time (compile-time polymorphism) through method overloading and operator overloading, and at runtime (run-time polymorphism) through method overriding.

So, while superclass and subclass are related to inheritance, and variable is a general term in programming, polymorphism is a specific pillar of Object-Oriented

Q: Which of the following is called java compiler?

A. javab
B. javac
C. javaCompiler
D. javacompile

Correct Option: B
Remarks:

Explanation:

Correct Answer: b. javac

Q: Question: Which of the following is not an object-oriented programming language?

A. C++
B. Simula
C. BASIC
D. Java

Correct Option: C
Remarks:

Explanation:

BASIC (Beginner's All-purpose Symbolic Instruction Code) is a procedural programming language and does not support object-oriented programming concepts such as classes, objects, inheritance, and polymorphism.

Basic Concept of OOP - Quiz

Which one of these lists contains only Java programming language keywords?

Which three are legal array declarations? int [] myScores []; char [] myChars; int [6] myScores; Dog myDogs []; Dog myDogs [7];

Which three are valid declarations of a char? char c1 = 064770; char c2 = 'face'; char c3 = 0xbeef; char c4 = \u0022; char c5 = '\iface'; char c6 = '\uface';

What is the numerical range of a char?

public class F0091 { public void main( String[] args ) { System.out.println( "Hello" + args[0] ); } } What will be the output of the program, if this code is executed with the command line: > java F0091 world

Which of the following is known as natural language?

Which of the following is a pillar of Object-Oriented programming?

Which of the following is called java compiler?

Question: Which of the following is not an object-oriented programming language?

Which three are legal array declarations?

int [] myScores [];

char [] myChars;

int [6] myScores;

Dog myDogs [];

Dog myDogs [7];

Which three are valid declarations of a char?

char c1 = 064770;

char c2 = 'face';

char c3 = 0xbeef;

char c4 = \u0022;

char c5 = '\iface';

char c6 = '\uface';

public class F0091 { public void main( String[] args ) { System.out.println( "Hello" + args[0] ); } }
What will be the output of the program, if this code is executed with the command line: > java F0091 world