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Java Interview Questions
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Java, the language, is a high-level object-oriented programming language, influenced in various ways by C, C++, and Smalltalk, with ideas borrowed from other languages as well (see O'Reilly's History of Programming Languages). Its syntax was designed to be familiar to those familiar with C-descended "curly brace" languages, but with arguably stronger OO principles than those found in C++, static typing of objects, and a fairly rigid system of exceptions that require every method in the call stack to either handle exceptions or declare their ability to throw them. Garbage collection is assumed, sparing the developer from having to free memory used by obsolete objects.
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Java FAQs - 1 |
Java FAQs - 2 |
Java FAQs - 3 |
Java FAQs - 4 |
Java FAQs - 5
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Java FAQs - 7 |
Java FAQs - 8 |
Java FAQs - 9 |
Java FAQs - 10
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Core Java Interview Questions - Part3
1.what is a transient variable?
A transient variable is a variable that may not be serialized.
2.which containers use a border Layout as their default layout?
The window, Frame and Dialog classes use a border layout as their default
layout.
3.Why do threads block on I/O?
Threads block on i/o (that is enters the waiting state) so that other threads
may execute
while the i/o Operation is performed.
4. How are Observer and Observable used?
Objects that subclass the Observable class maintain a list of observers. When an
Observable object is updated it invokes the update() method of each of its
observers to
notify the observers that it has changed state. The Observer interface is
implemented by
objects that observe Observable objects.
5. What is synchronization and why is it important?
With respect to multithreading, synchronization is the capability to control the
access of
multiple threads to shared resources. Without synchronization, it is possible
for one
thread to modify a shared object while another thread is in the process of using
or
updating that object's value. This often leads to significant errors.
6. Can a lock be acquired on a class?
Yes, a lock can be acquired on a class. This lock is acquired on the class's
Class object..
7. What's new with the stop(), suspend() and resume() methods in JDK 1.2?
The stop(), suspend() and resume() methods have been deprecated in JDK 1.2.
8. Is null a keyword?
The null value is not a keyword.
9. What is the preferred size of a component?
The preferred size of a component is the minimum component size that will allow
the
component to display normally.
10. What method is used to specify a container's layout?
The setLayout() method is used to specify a container's layout.
11. Which containers use a FlowLayout as their default layout?
The Panel and Applet classes use the FlowLayout as their default layout.
12. What state does a thread enter when it terminates its processing?
When a thread terminates its processing, it enters the dead state.
13. What is the Collections API?
The Collections API is a set of classes and interfaces that support operations
on
collections of objects.
14. Which characters may be used as the second character of an identifier,
but not as the first character of an identifier?
The digits 0 through 9 may not be used as the first character of an identifier
but they may
be used after the first character of an identifier.
15. What is the List interface?
The List interface provides support for ordered collections of objects.
16. How does Java handle integer overflows and underflows?
It uses those low order bytes of the result that can fit into the size of the
type allowed by
the operation.
17. What is the Vector class?
The Vector class provides the capability to implement a growable array of
objects
18. What modifiers may be used with an inner class that is a member of an outer
class?
A (non-local) inner class may be declared as public, protected, private, static,
final, or
abstract.
19. What is an Iterator interface?
The Iterator interface is used to step through the elements of a Collection.
20. What is the difference between the >> and >>> operators?
The >> operator carries the sign bit when shifting right. The >>>
zero-fills bits that have
been shifted out.
21. Which method of the Component class is used to set the position and
size of a component?
setBounds()
22. How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8
characters?
Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character
set uses
only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters
using 8, 16,
and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns.
23What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready state. When a
task invokes
its sleep() method, it returns to the waiting state.
24. Which java.util classes and interfaces support event handling?
The EventObject class and the EventListener interface support event processing.
25. Is sizeof a keyword?
The sizeof operator is not a keyword.
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