Java Interview Questions and Answers

Q8. Which of the following is not a Java features?

1. Dynamic
2. Architecture Neutral
3. Use of pointers
4. Object-oriented

Ans:Dynamic

Q9. What is the return type of the hashCode() method in the Object class?

1. Object
2. INT
3. Long
4. Void

Ans: INT

Q10. What does the expression float a = 35 / 0 return?

1. 0
2. Not a Number
3. Infinity
4. Run time exception

Ans: Infinity

Q11. Which of the following creates a List of 3 visible items and multiple selections abled?

1. new List(false, 3)
2. new List(3, true)
3. new List(true, 3)
4. new List(3, false)

Ans: new List(3, true)

Q12. Which of the following is true about the anonymous inner class?

1. It has only methods
2. Objects can't be created
3. It has a fixed class name
4. It has no class name

Ans: It has no class name

Q13. Which of these classes are the direct subclasses of the Throwable class?

1. RuntimeException and Error class
2. Exception and VirtualMachineError class
3. Error and Exception class
4. IOException and VirtualMachineError class

Ans: Error and Exception class

Q14. What do you mean by chained exceptions in Java?

1. Exceptions occurred by the VirtualMachineError
2. An exception caused by other exceptions
3. Exceptions occur in chains with discarding the debugging information
4. None of the above

Ans: An exception caused by other exceptions

Q15. What is the use of the intern() method?

1. It returns the existing string from memory
2. It creates a new string in the database
3. It modifies the existing string in the database
4. None of the above

Ans: It returns the existing string from memory

Q16. Out of these statements, which ones are incorrect?

1. The Brackets () have the highest precedence
2. The equal to = operator has the lowest precedence
3. The addition operator + and the subtraction operator – have an equal precedence
4. The division operator / has comparatively higher precedence as compared to a multiplication operator

Ans: The division operator / has comparatively higher precedence as compared to a multiplication operator

Q17. Out of these methods of the String class, which one can be used for testing the strings for equality?

1. isequals()
2. isequal()
3. equals()
4. equal()

Ans: equals()

Q18. Which of these interface handle sequences?

1. Set
2. List
3. Comparator
4. Collection

Ans: List

Q19. Which of this interface must contain a unique element?

1. Set
2. List
3. Comparator
4. Collection

Ans: Set

Q20. Which of the following is true about primitives?

1. You can call methods on a primitive.
2. You can convert a primitive to a wrapper class object simply by assigning it.
3. You can convert a wrapper class object to a primitive by calling valueOf().
4. You can store a primitive directly into an ArrayList.

Ans: You can convert a primitive to a wrapper class object simply by assigning it.

Q21. How do you force garbage collection to occur at a certain point?

1. Call System.forceGc()
2. Call System.gc()
3. Call System.requireGc()
4. None of the above

Ans: None of the above

Q22. How do you reverse a string in Java?

Ans: There is no reverse() utility method in the String class. However, you can create a character array from the string and then iterate it from the end to the start. You can append the characters to a string builder and finally return the reversed string.

The following example code shows one way to reverse a string:

public class StringPrograms {

public static void main(String[] args) {

String str = "123";

System.out.println(reverse(str));

}

public static String reverse(String in) {

if (in == null)

throw new IllegalArgumentException("Null is not valid input");

StringBuilder out = new StringBuilder();

char[] chars = in.toCharArray();

for (int i = chars.length - 1; i >= 0; i--)

out.append(chars[i]);

return out.toString();

} }

Bonus points for adding null check in the method and using StringBuilder for appending the characters. Note that the indexing in Java starts from 0, so you need to start at chars.length - 1 in the for loop.

Q23. What do you mean by >>> operator in Java?

1. Left Shift Operator
2. Right Shift Operator
3. Zero Fill Right Shift
4. Zero Fill Left Shift

Ans: Zero Fill Right Shift