50 TOP JAVA LAB VIVA Questions and Answers Pdf

JAVA LAB VIVA Questions with Answers :-

1.What is JVM?

2. What is the most important feature of Java?

3. What do you mean by platform independence?

4. What is the difference between a JDK and a JVM?

5. What is the base class of all classes?

6. What are the access modifiers in Java?

7. What is are packages?

8. What is meant by Inheritance and what are its advantages?

9. What is the difference between superclass and subclass?

10. What is an abstract class?

11. What are the states associated in the thread?

12. What is synchronization?

13. What is deadlock?

14. What is an applet?

15. What is the lifecycle of an applet?

JAVA VIVA Questions and Answers :-

16. How do you set security in applets?

17. What is a layout manager and what are different types of layout managers available in java AWT?

18. What is JDBC?

19. What are drivers available?

20. What is stored procedure?

21. What is the Java API?

22. Why there are no global variables in Java?

23. What are Encapsulation, Inheritance and Polymorphism?

24. What is the use of bin and lib in JDK?

25. What is method overloading and method overriding?

26. What is the difference between this() and super()?

27. What is Domain Naming Service(DNS)?

28. What is URL?

29. What is RMI and steps involved in developing an RMI object?

30. What is RMI architecture?

31. Why Java?
The programs that we are writing are very similar to their counterparts in several other languages, so our choice of language is not crucial. We use Java because it is widely available, embraces a full set of modern abstractions, and has a variety of automatic checks for mistakes in programs, so it is suitable for learning to program. There is no
perfect language, and you certainly will be programming in other languages in the future.

32. Do I really have to type in the programs in the book to try them out?
Everyone should type in HelloWorld.java, but you can find all of the code in this book (and much more) on this booksite.

33. What are Java’s rules regarding tabs, spaces and newline characters?
There are not many. Java compilers treat them all to be equivalent. For example, we could also write HelloWorld as follows:

public class HelloWorld { public static void main (
String [] args) { System.out.println(“Hello World”) ; } }

But we do normally adhere to spacing and indenting conventions when we write Java programs, just as we always indent paragraphs and lines consistently when we write prose or poetry.

34. What are the rules regarding quotation marks?
Material inside quotation marks is an exception to the rule of the previous question:
things within quotes are taken literally so that you can precisely specify what gets printed. If you put any number of successive spaces within the quotes, you get that number of spaces in the output. If you accidentally omit a quotation mark, the compiler may get very confused, because it needs that mark to distinguish between characters in the string and other parts of the program. To print a quotation mark, a newline, or a tab, use \”, \n, or \t, respectively, within the quotation marks.

35. What is the meaning of the words public, static and void?
These keywords specify certain properties of main() that you will learn about later in the book. For the moment, we just include these keywords in the code (because they are required) but do not refer to them in the text.

36. What happens when you omit a brace or misspell one of the words, like public or
static or main?
It depends upon precisely what you do. Such errors are called syntax errors. Try it out and see.

37. Can a program use more than one command-line argument?
Yes, you can put several, though we normally use only a few. You refer to the second one as args[1], the third one as args[2], and so forth. Note that we start counting from 0 in Java.

38. What Java systems libraries and methods are available for me to use?
There are thousands of them, but we introduce them to you in a deliberate fashion in this book to avoid overwhelming you with choices.

39. How should I format my code? How should I comment my code?
Programmers use coding guidelines to make programs easier to read, understand, and maintain. As you gain experience, you will develop a coding style, just as you develop style when writing prose. Appendix B provides some guidelines for formatting and commenting your code. We recommend returning to this appendix after you’ve written a few programs.

40. What exactly is a .class file?
It’s a binary file (sequence of 0s and 1s). If you are using Unix or OS X, you can examine its contents by typing od -x HelloWorld.class at the command prompt. This displays the results in hexadecimal (base 16). In deference to Java’s name, the first word of every .class file is cafe.

41. How do I get the | symbol on my keyboard?
It’s there. Often it’s above the \ symbol.

42. Java prints out a ton of digits when I System.out.println() a double. How can I format it so it displays only 3 digits after the decimal place?
Use the method System.out.printf() described in Section 1.5.

43. Why does the integer quotient -0/3 yield 0, but the double quotient -0.0/3.0 yields – 0.0?
Java represent integers using something called two’s complement notation, and there is only one representation of 0. (You’ll learn about this in Section 5.1.) Java represents doubles using IEEE specifications, and there are two distinct representations of the number zero, 0 and -0. (You’ll learn about this in Section 9.1.)

44. What happens when I use / and % with a negative numerator?
Try it and see. -47 / 5 = -9 and -47 % 5 = -2. The quotient is always rounded toward zero. To ensure the Euclidean property b * (a / b) + (a % b) = a, the result of the remainder operator can be negative. This convention was inherited from ancestral

languages like FORTRAN and C. Some languages (but not Java) include both remainder and modulo operators because it is often convenient to have a version that returns only nonnegative integers.

45. Can I use % with real numbers?
Yes. If angle is nonnegative, then angle % (2 * Math.PI) converts the angle to be
between 0 and 2 π.

46. How do I print a “?
Since ” is a special character when dealing with strings, you must escape the convention rules by using \”. For example, System.out.println(“The pig said \”Oink Oink\” afterwards”);.

47. OK, so then how do I print a \?
Use “\\”.

48. Why do I need to declare the type of a variable in Java?
By specifying the type, the compiler can alert you of potential errors, say if you try to multiply an integer with a string. For the same reason, when doing physics calculations, it is always a good idea to keep track of the units and make sure they “type check.” For small programs, this may not seem important; for large programs it is crucial. The Ariane 5 rocket exploded 40 seconds after takeoff because of a bug in its software that incorrectly converted a 64 bit real number into a 16 bit integer.

49. Why is the type for real numbers called double?
Historically, the type for floating point numbers was float, but they had limited
accuracy. The type double was introduced as a floating point type with twice as much

50. Is it correct to say that using parentheses can only change
Almost, with one surprising exception. The literal value 2147483648 (2^31) is only permitted as an operand of the unary minus operator, i.e., -2147483648. Enclosing it in parentheses, i.e., -(2147483648), leads to a compile-time error.

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