Java Programming Test! Hardest Trivia Questions Quiz

1. Given:

public class Test{
    public static void main(String[] args) {
        Test obj = new Test();
        short letter = 97;
        int letter2 = 98;
        System.out.print((char) letter + " ");
        System.out.print((char) letter2);
    }
}

What is the result?

A b

Afollowed by an exception

Compilation fails

A ClassCastException is thrown at runtime.

The code first creates an instance of the Test class. It then assigns the value 97 to a variable named "letter" of type short, and assigns the value 98 to a variable named "letter2" of type int.

In the first print statement, the value of "letter" is casted to a char, which corresponds to the ASCII value of 'a'. The second print statement directly prints the char value of "letter2", which corresponds to the ASCII value of 'b'.

Therefore, the result of the code is "a b".

Explanation

The code first creates an instance of the Test class. It then assigns the value 97 to a variable named "letter" of type short, and assigns the value 98 to a variable named "letter2" of type int.

In the first print statement, the value of "letter" is casted to a char, which corresponds to the ASCII value of 'a'. The second print statement directly prints the char value of "letter2", which corresponds to the ASCII value of 'b'.

Therefore, the result of the code is "a b".

2. Given the code fragment:

public static void main(String[] args) {
    int a = 10;
    float b = 10.25f;
    double c = 100;
    a = b; // line 7
    b = a; // line 8
    c = b; // line 9
    c = a; // line 10
}

Which change enables the code fragment to compile successfully?

Replace line 10 with c = (double) a;

Replace line 8 with b = (float) a;

Replace line 7 with a = (int) b;

Replace line 9 with c = (double) b;

The code fragment does not compile successfully because there are incompatible data types being assigned to variables. In order to fix this, we need to explicitly cast the incompatible data types to compatible ones. In this case, replacing line 7 with "a = (int) b;" will cast the float variable b to an int, allowing it to be assigned to the int variable a.

Explanation

The code fragment does not compile successfully because there are incompatible data types being assigned to variables. In order to fix this, we need to explicitly cast the incompatible data types to compatible ones. In this case, replacing line 7 with "a = (int) b;" will cast the float variable b to an int, allowing it to be assigned to the int variable a.

3. Given:

public class Test{
    public static void main(String[] args) {
        Test obj = new Test();
        short letter = 97;
        int letter2 = 98;
        int long = 99;
        System.out.print((char) letter + " ");
        System.out.print((char) letter2);
    }
}

What is the result?

A b

A followed by an exception

Compilation fails.

A ClassCastException is thrown at runtime.

The code fails to compile because "long" is a reserved keyword in Java and cannot be used as a variable name.

Explanation

The code fails to compile because "long" is a reserved keyword in Java and cannot be used as a variable name.

4. Given:

public class Test{
    public static void main(String[] args) {
        short letter;
        int letter2 = letter + 2; // line n1
        System.out.print((short) letter2); // line n2
    }
}

What is the result?

Compilation fails at line n1.

Compilation fails at line n2.

A exception is thrown at line n1.

A exception is thrown at line n2.

The compilation fails at line n1 because the variable "letter" is declared but not initialized before it is used in the expression "letter + 2". Since the value of "letter" is not known at this point, the compiler cannot perform the addition and assign the result to "letter2". To fix this error, the variable "letter" should be assigned a value before line n1.

Explanation

The compilation fails at line n1 because the variable "letter" is declared but not initialized before it is used in the expression "letter + 2". Since the value of "letter" is not known at this point, the compiler cannot perform the addition and assign the result to "letter2". To fix this error, the variable "letter" should be assigned a value before line n1.

5. Given the code fragment:

public static void main(String[] args) {
    short s1 = 200;
    int s2 = 400;
    long s3 = (long) s1 + s2; // line n1
    String s4 = (String) (s3 * s2 ); // line n2
    System.out.println("Sum is " + s4);
}

What is the result?

Sum is 600

Compilation fails at line n1.

Compilation fails at line n2.

A exception is thrown at line n1.

A exception is thrown at line n2.

The code will fail to compile at line n2 because it is attempting to cast a long value to a String, which is not allowed.

Explanation

The code will fail to compile at line n2 because it is attempting to cast a long value to a String, which is not allowed.