Java Language Fundamental - Quiz

Q: Number of primitive data types in Java are?

A. 2
B. 4
C. 10
D. 8

Correct Option: D
Explanation: There are 8 types of primitive data types- int, char, boolean, byte, long, float, short, double.

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
Explanation:

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

Q: What will be the output of the program ?

public class Test 
{
    public static void main(String [] args) 
    {
        signed int x = 10;
        for (int y=0; y<5; y++, x--)
            System.out.print(x + ", ");
    }
}

A. 10, 9, 8, 7, 6,
B. 9, 8, 7, 6, 5,
C. Compilation fails.
D. An exception is thrown at runtime.

Correct Option: C
Explanation:

The word "signed" is not a valid modifier keyword in the Java language. All number primitives in Java are signed. Hence the Compilation will fails.

Q: Java is a _________ language.

A. weakly typed
B. strogly typed
C. moderate typed
D. None of these

Correct Option: B
Explanation: strogly typed

Q: Which is a reserved word in the Java programming language? native

A. method
B. native
C. subclasses
D. reference

Correct Option: B
Explanation:

The word "native" is a valid keyword, used to modify a method declaration.

Option A, D and E are not keywords. Option C is wrong because the keyword for subclassing in Java is extends, not 'subclasses'.

Q: Which is the valid declarations within an interface definition?

A. public double methoda();
B. public final double methoda();
C. static void methoda(double d1);
D. protected void methoda(double d1);

Correct Option: A
Explanation:

Option A is correct. A public access modifier is acceptable. The method prototypes in an interface are all abstract by virtue of their declaration, and should not be declared abstract.

Option B is wrong. The final modifier means that this method cannot be constructed in a subclass. A finalmethod cannot be abstract.

Option C is wrong. static is concerned with the class and not an instance.

Option D is wrong. protected is not permitted when declaring a method of an interface. See information below.

Member declarations in an interface disallow the use of some declaration modifiers; you cannot use transient, volatile, or synchronized in a member declaration in an interface. Also, you may not use the private and protected specifiers when declaring members of an interface.

Q: Which will legally declare, construct, and initialize an array?

A. int [] myList = {"1", "2", "3"};
B. int [] myList = (5, 8, 2);
C. int myList [] [] = {4,9,7,0};
D. int myList [] = {4, 3, 7};

Correct Option: D
Explanation:

The only legal array declaration and assignment statement is Option D

Option A is wrong because it initializes an int array with String literals.

Option B is wrong because it use something other than curly braces for the initialization.

Option C is wrong because it provides initial values for only one dimension, although the declared array is a two-dimensional array.

Q: Which one of the following will declare an array and initialize it with five numbers?

A. Array a = new Array(5);
B. int [] a = {23,22,21,20,19};
C. int a [] = new int[5];
D. int [5] array;

Correct Option: B
Explanation:

Option B is the legal way to declare and initialize an array with five elements.

Option A is wrong because it shows an example of instantiating a class named Array, passing the integer value 5 to the object's constructor. If you don't see the brackets, you can be certain there is no actual array object! In other words, an Array object (instance of class Array) is not the same as an array object.

Option C is wrong because it shows a legal array declaration, but with no initialization.

Option D is wrong (and will not compile) because it declares an array with a size. Arrays must never be given a size when declared.

Q:

public interface Foo 
{ 
    int k = 4; /* Line 3 */
}

Which three piece of codes are equivalent to line 3?

final int k = 4;
public int k = 4;
static int k = 4;
abstract int k = 4;
volatile int k = 4;
protected int k = 4;

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

Correct Option: A
Explanation:

(1), (2) and (3) are correct. Interfaces can have constants, which are always implicitly public, static, and final. Interface constant declarations of public, static, and final are optional in any combination.

Q: What will be the output of the program?

public class CommandArgsTwo 
{
    public static void main(String [] argh) 
    {
        int x;
        x = argh.length;
        for (int y = 1; y <= x; y++) 
        {
            System.out.print(" " + argh[y]);
        }
    }
}

and the command-line invocation is

> java CommandArgsTwo 1 2 3

A. 0 1 2
B. 1 2 3
C. 0 0 0
D. An exception is thrown at runtime

Correct Option: D
Explanation:

An exception is thrown because at some point in (System.out.print(" " + argh[y]);), the value of x will be equal to y, resulting in an attempt to access an index out of bounds for the array. Remember that you can access only as far as length - 1, so loop logical tests should use x < someArray.length as opposed to x < = someArray.length.

Java Language Fundamental - Quiz

Number of primitive data types in Java are?

What is the numerical range of a char?

What will be the output of the program ?
public class Test { public static void main(String [] args) { signed int x = 10; for (int y=0; y<5; y++, x--) System.out.print(x + ", "); } }

Java is a _________ language.

Which is a reserved word in the Java programming language? native

Which is the valid declarations within an interface definition?

Which will legally declare, construct, and initialize an array?

Which one of the following will declare an array and initialize it with five numbers?

public interface Foo { int k = 4; /* Line 3 */ }
Which three piece of codes are equivalent to line 3?

final int k = 4;

public int k = 4;

static int k = 4;

abstract int k = 4;

volatile int k = 4;

protected int k = 4;

What will be the output of the program?
public class CommandArgsTwo { public static void main(String [] argh) { int x; x = argh.length; for (int y = 1; y <= x; y++) { System.out.print(" " + argh[y]); } } }

and the command-line invocation is

> java CommandArgsTwo 1 2 3

Java Language Fundamental - Quiz

Number of primitive data types in Java are?

What is the numerical range of a char?

What will be the output of the program ? public class Test { public static void main(String [] args) { signed int x = 10; for (int y=0; y<5; y++, x--) System.out.print(x + ", "); } }

Java is a _________ language.

Which is a reserved word in the Java programming language? native

Which is the valid declarations within an interface definition?

Which will legally declare, construct, and initialize an array?

Which one of the following will declare an array and initialize it with five numbers?

public interface Foo { int k = 4; /* Line 3 */ } Which three piece of codes are equivalent to line 3? final int k = 4; public int k = 4; static int k = 4; abstract int k = 4; volatile int k = 4; protected int k = 4;

What will be the output of the program? public class CommandArgsTwo { public static void main(String [] argh) { int x; x = argh.length; for (int y = 1; y <= x; y++) { System.out.print(" " + argh[y]); } } } and the command-line invocation is > java CommandArgsTwo 1 2 3

What will be the output of the program ?
public class Test { public static void main(String [] args) { signed int x = 10; for (int y=0; y<5; y++, x--) System.out.print(x + ", "); } }

public interface Foo { int k = 4; /* Line 3 */ }
Which three piece of codes are equivalent to line 3?

final int k = 4;

public int k = 4;

static int k = 4;

abstract int k = 4;

volatile int k = 4;

protected int k = 4;

What will be the output of the program?
public class CommandArgsTwo { public static void main(String [] argh) { int x; x = argh.length; for (int y = 1; y <= x; y++) { System.out.print(" " + argh[y]); } } }

and the command-line invocation is

> java CommandArgsTwo 1 2 3