Questions and answers for exam Preparation

MCQs

Total Questions : 9

Question 1.

What is the output of this program?

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

Hello c
Hello
Hello world
Runtime Error.

Discuss Question

Answer: Option D. -> Runtime Error.

A runtime error will occur owning to the main method of the code fragment not being declared static.
Output:
$ javac c.java
Exception in thread "main" java.lang.NoSuchMethodError: main

Question 2.

What is the output of this program?

class A {
final public int calculate(int a, int b) { return 1; }
}
class B extends A {
public int calculate(int a, int b) { return 2; }
}
public class output {
public static void main(String args[])
{
B object = new B();
System.out.print("b is " + b.calculate(0, 1));
}
}

b is : 2
b is : 1
Compilation Error.
An exception is thrown at runtime.

Discuss Question

Answer: Option C. -> Compilation Error.

The code does not compile because the method calculate() in class A is final and so cannot

be overridden by method of class b.

Question 3.

What is the output of this program?

class conversion {
public static void main(String args[])
{
double a = 295.04;
int b = 300;
byte c = (byte) a;
byte d = (byte) b;
System.out.println(c + " " + d);
}
}

38 43
39 44
295 300
295.04 300

Discuss Question

Answer: Option B. -> 39 44

Type casting a larger variable into a smaller variable results in modulo of larger variable by

range of smaller variable. b contains 300 which is larger than byteâ€™s range i:e -128 to 127

hence d contains 300 modulo 256 i:e 44.
output:
$ javac conversion.java
$ java conversion
39 44

Question 4.

What is the output of this program?

class char_increment {
public static void main(String args[])
{
char c1 = 'D';
char c2 = 84;
c2++;
c1++;
System.out.println(c1 + " " + c2);
}
}

Discuss Question

Answer: Option A. -> E U

Operator ++ increments the value of character by 1. c1 and c2 are given values D and 84, when

we use ++ operator their values increments by 1, c1 and c2 becomes E and U respectively.

output:
$ javac char_increment.java
$ java char_increment
E U

Question 5.

What is Truncation is Java?

Floating-point value assigned to an integer type.
Integer value assigned to floating type.
Floating-point value assigned to an Floating type.
Integer value assigned to floating type.

Discuss Question

Answer: Option A. -> Floating-point value assigned to an integer type.

None.

Question 6.

If an expression contains double, int, float, long, then whole expression will promoted into

which of these data types?

long
int
double
float

Discuss Question

Answer: Option C. -> double

If any operand is double the result of expression is double.

Question 7.

What is the error in this code?
byte b = 50;
b = b * 50;

b can not contain value 100, limited by its range.
* operator has converted b * 50 into int, which can not be converted to byte without casting.
b can not contain value 50.
No error in this code

Discuss Question

Answer: Option B. -> * operator has converted b * 50 into int, which can not be converted to byte without casting.

While evaluating an expression containing int, bytes or shorts , the whole expression is

converted to int then evaluated and result is also of type int.

Question 8.

Which of these is necessary condition for automatic type conversion in Java?