Java QB.

Question Bank

Programming with Core Java

Unit -I

1. What is the most important feature of Java?
2. Explain platform independence
3. What is a JVM? Are JVMs platform independent?
4. Differentiate between a JDK and a JVM?
5. What is a pointer? Does Java support pointers?
6. What are local variables? What are instance variables?
7. In Java, how is a constant variable defined?
8. Is it compulsory to use a main() method in all java classes?
9. What is the return type of the main() method? What is the reason behind declaring the main() method static?
10. What is the argument of main() method?
11. Can we overload a main() method?
12. Can we declare a main() method final?
13. Does the order of public and static declaration matter in main() method?
14. What is a package? Which package is imported by default?
15. Can a class be declared as protected?
16. Elaborate the access scope of a protected method?
17. Elaborate the purpose of declaring a variable as final? Explain impact of declaring a method as final?
18. If we do not want our class to be inherited by any other class what should we do?
19. Can you give few examples of final classes defined in Java API?
20. Differentiate final from finally and finalize()?
21. Can we declare a class as static?
22. When can a method be defined as static?
23. Explain the significance of static variable?
24. Can a static variable be declared inside a method?
25. What is the % operator?
26. When can an object reference be cast to an interface reference?
27. Which class is extended by all other classes?
28. Which non-Unicode letter characters may be used as the first character of an identifier?
29. What are the restrictions placed on method overloading?
30. What is casting?
31. What is the return type of a program's main() method?
32. Where can the variable be accessed when it is declared as private?
33. What do you understand by private, protected and public?
34. Explain Downcasting.
35. What modifiers may be used with an inner class that is a member of an outer class?
36. How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
37. What are the restrictions placed on the location of a package statement within a source code file?
38. What is a native method?
39. What are order of precedence and associativity and how are they used?
40. Can an anonymous class be declared as implementing an interface and extending a class?
41. What is the range of the char type?
42. What is the range of the short type?
43. Why doesn't operator overloading exist?
44. What does it mean when we say that a method or field is "static"?
45. Is null a keyword?
46. Which characters may be used as the second but not as the first character of an identifier?
47. Is the ternary operator written x : y ? z or x ? y : z ?
48. How is rounding performed under integer division?
49. If a class is declared without any access modifiers, where may the class be accessed?
50. Does a class inherit the constructors of its superclass?
51. Name the eight primitive Java types.
52. What are the restrictions that are placed on the values of each case of a switch statement?
53. Differentiate between a while statement and a do while statement?
54. What all modifiers can be used with a local inner class?
55. When does the compiler supply a default constructor for a class?
56. Where may a method be accessed if it is declared as protected?
57. Elaborate the legal operands of the instance of operator?
58. Are true and false keywords?
59. What happens when you add a double value to a String?
60. Differentiate between inner class and nested class.
61. Can an abstract class be final?
62. What is numeric promotion?
63. To what value is a variable of the boolean type automatically initialized?
64. Differentiate between the prefix and postfix forms of the ++ operator.
65. What modifiers may be used with a top-level class?
66. Differentiate between an if statement and a switch statement?
67. What are the practical benefits, if any, of importing a specific class rather than an entire package (e.g.import java.net.* versus import java.net.Socket)?
68. Can we overload a method based on different return type but same argument type?
69. What happens to a static variable that is defined within a method of a class?
70. How many static initializers are there?
71. Differentiate between method overriding and overloading?
72. What is constructor chaining and how is it achieved in Java?
73. How are this() and super() used with constructors?
74. What does it mean that a class or member is final?
75. What does it mean that a method or class is abstract?

Unit -II

What is mean by OOP? Explain OOP Concepts?
Explain in detail about Garbage Collector in Java.
What is a Constructor? Explain types of Constructors in Java?
Discuss about the static, final keywords with an example
Recall Inheritance? Illustrate the types of inheritances.
Write a java program to implement multilevel inheritance concept.
Discuss about the super keyword in java with example.
Compare Method Overriding and Method Overloading.
Why interface is required?
What is use of abstract class?
Give the differences between Abstract class and Interface
Which class does not override the equals() and hashCode() methods, inheriting them directly from class Object?
Difference between == and .equals() ?
What are the methods of Object Class ?
What are different ways of object creation in Java ?
What is a cloneable interface and what all methods does it contain?
Why do we use a copy constructor ?
Does it make sense to clone an object which is supposed to be immutable ?
What is a prototype design pattern ?
Explain CloneNotSupportedException ?
What is ArrayList in Java?
Explain the hierarchy of ArrayList class in Java.
Which marker interfaces are implemented by Java ArrayList?
Which collection classes implement List interface in Java?
What are the important features of ArrayList in Java?
Why is ArrayList called a dynamically growing array in Java?
How to create a generic ArrayList object in Java?
How to add elements to Java ArrayList?
Does ArrayList allow to insert duplicate elements?
Is it possible to add null into ArrayList?

Unit -III

Describe the difference between unchecked and checked exceptions in Java.
What is the difference between finally, final, and finalize in Java?
Define try-with resource. How can you say that it differs from an ordinary try?
Define Runtime Exception. Describe it with the help of an example.
What is the difference between NoClassDefFoundError and ClassNotFoundException in Java?
Can we throw an exception explicitly or manually?
Describe the use of the throw keyword.
Why should we clean up activities such as I/O resources in the finally block?
Describe OutofMemoryError in exception handling.
What is the error of ClassCastException?
Is there any difference between throw and throws in exception handling in Java?
When should we use the printStackTrace() method?
Provide me with some examples of unchecked exceptions.
Is it illegal to keep an empty catch?
What are the advantages of using exception handling in Java?
Can checked exceptions occur at compiled time?
What happens if a runtime exception occurs?
Describe unreachable catch block error in Java.
In which situation will you not be able to execute the finally block?
Is it possible to throw a statement inside a static block?
Define rethrowing.
Define user-defined or custom exceptions in Java.
What do you understand by a chained exception?
What do you understand about throwables in Java?
Mention the methods in the throwable class.
Give me some examples of checked exceptions.
Define NumberFormatException exception in Java.
What do you understand by ArrayIndexOutOfBoundsException?
Suppose there is a catch block in tune with a try block with 3 statements - 1, 2, and 3. Now, imagine that the statement is thrown in statement 2. Will there be an execution of statement 3?
Define unreachable catch block error.
Tell something about BufferedWriter ? What are flush() and close() used for ?
What is Scanner class used for ? when was it introduced in Java ?
What is a stream and what are the types of Streams and classes of the Streams?
What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?
Which is the abstract parent class of FileWriter ?
Which class is used to read streams of raw bytes from a file?
Which is the Parent class of FileInputStream ?
Which exceptions should be handled with the following code ?
Which is the Parent Class of ByteArrayInputStream and AudioInputStream ?
Which interfaces are implemented by InputStream?
What is the package name for ObjectInputStream class?
Which is the Parent Class of SequenceInputStream class?
Which is the Parent Class of FilterInputStream class?
What is the package name for FilterInputStream class?
Which interfaces are implemented by FileInputStream?
Which is the Parent Class of InputStream class?
Which is the Parent Class of FileInputStream class?
How do you read a file line by line in Java?
How do you check if a file is hidden in Java?
What is difference between getPath(), getCanonicalPath() and getAbsolutePath() in Java?