AMD Wants To Depose 486
People in Intel Case
AMD News Desk wrote:
Contrary to what you may
have read elsewhere, AMD
has...
May. 9, 2008 01:06 PM
|
 |
 |
|
|
|
|
YOUR FEEDBACK
Did you read today's front page stories & breaking news?
SOA World Conference
Virtualization Conference $200 Savings Expire May 16, 2008... – Register Today!
SYS-CON.TV |
TOP THREE LINKS YOU MUST CLICK ON Java Industry News
Secrets Of The Masters: Core Java Job Interview Questions
JDJ Enterprise Editor Yakov Fain Offers 30 Core Java Questions You Might Expect During Job Interviews
By: Yakov Fain
May. 2, 2007 08:30 PM
Digg This!
30 Java Interview Questions* Q1. How could Java classes direct program messages to the system console, but error messages, say to a file?  A. The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output could be re-directed:Stream st = new Stream(new FileOutputStream("output.txt")); System.setErr(st); System.setOut(st); * Q2. What's the difference between an interface and an abstract class? A. An abstract class may contain code in method bodies, which is not allowed in an interface. With abstract classes, you have to inherit your class from it and Java does not allow multiple inheritance. On the other hand, you can implement multiple interfaces in your class. * Q3. Why would you use a synchronized block vs. synchronized method? A. Synchronized blocks place locks for shorter periods than synchronized methods. * Q4. Explain the usage of the keyword transient? A. This keyword indicates that the value of this member variable does not have to be serialized with the object. When the class will be de-serialized, this variable will be initialized with a default value of its data type (i.e. zero for integers). * Q5. How can you force garbage collection? A. You can't force GC, but could request it by calling System.gc(). JVM does not guarantee that GC will be started immediately. * Q6. How do you know if an explicit object casting is needed? A. If you assign a superclass object to a variable of a subclass's data type, you need to do explicit casting. For example: Object a; Customer b; b = (Customer) a; When you assign a subclass to a variable having a supeclass type, the casting is performed automatically. * Q7. What's the difference between the methods sleep() and wait() A. The code sleep(1000); puts thread aside for exactly one second. The code wait(1000), causes a wait of up to one second. A thread could stop waiting earlier if it receives the notify() or notifyAll() call. The method wait() is defined in the class Object and the method sleep() is defined in the class Thread. * Q8. Can you write a Java class that could be used both as an applet as well as an application? A. Yes. Add a main() method to the applet. * Q9. What's the difference between constructors and other methods? A. Constructors must have the same name as the class and can not return a value. They are only called once while regular methods could be called many times. * Q10. Can you call one constructor from another if a class has multiple constructors A. Yes. Use this() syntax. * Q11. Explain the usage of Java packages. A. This is a way to organize files when a project consists of multiple modules. It also helps resolve naming conflicts when different packages have classes with the same names. Packages access level also allows you to protect data from being used by the non-authorized classes. * Q12. If a class is located in a package, what do you need to change in the OS environment to be able to use it? A. You need to add a directory or a jar file that contains the package directories to the CLASSPATH environment variable. Let's say a class Employee belongs to a package com.xyz.hr; and is located in the file c:\dev\com\xyz\hr\Employee.java. In this case, you'd need to add c:\dev to the variable CLASSPATH. If this class contains the method main(), you could test it from a command prompt window as follows: c:\>java com.xyz.hr.Employee * Q13. What's the difference between J2SDK 1.5 and J2SDK 5.0? A.There's no difference, Sun Microsystems just re-branded this version. * Q14. What would you use to compare two String variables - the operator == or the method equals()? A. I'd use the method equals() to compare the values of the Strings and the == to check if two variables point at the same instance of a String object. * Q15. Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written? A. Yes, it does. The FileNoFoundException is inherited from the IOException. Exception's subclasses have to be caught first. * Q16. Can an inner class declared inside of a method access local variables of this method? A. It's possible if these variables are final. * Q17. What can go wrong if you replace && with & in the following code: String a=null; if (a!=null && a.length()>10) {...} A. A single ampersand here would lead to a NullPointerException. * Q18. What's the main difference between a Vector and an ArrayList A. Java Vector class is internally synchronized and ArrayList is not. * Q19. When should the method invokeLater()be used? A. This method is used to ensure that Swing components are updated through the event-dispatching thread. * Q20. How can a subclass call a method or a constructor defined in a superclass? A. Use the following syntax: super.myMethod(); To call a constructor of the superclass, just write super(); in the first line of the subclass's constructor. Page 1 of 2 next page »
LATEST JAVA STORIES & POSTS
SUBSCRIBE TO THE WORLD'S MOST POWERFUL NEWSLETTERS SUBSCRIBE TO OUR RSS FEEDS & GET YOUR SYS-CON NEWS LIVE!
|
SYS-CON FEATURED WHITEPAPERS MOST READ THIS WEEK BREAKING JAVA NEWS
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
| | | | | | | | |
|
|
|
|
|
|
| | | | | | | | | | | | | | | | |
|
|
| SYS-CON MEDIA: | | | | |
| SYS-CON EVENTS: | | | | | |
| INTERNATIONAL SITES: | | | | | | | | | | |
 |
Terms of Use & Our Privacy Statement  About Newsfeeds / Video Feeds |
| Copyright ©1994-2008 SYS-CON Publications, Inc. All Rights Reserved. All marks are trademarks of SYS-CON Media. |
| Reproduction in whole or in part in any form or medium without express written permission of SYS-CON Publications, Inc. is prohibited. |
.gif)
JDJ's Enterprise Editor, Yakov Fain (pictured) writes: If you are planning to hit the job market, you may need to refresh some of the Java basic terms and techniques to prepare yourself for a technical interview. Let me offer you some of the core Java questions that you might expect during the interviews. 
Sun's mule train has
finally pulled into
Indiana after three years
on the road. Indiana is
the Linux-friendly
Fedora-like OpenSolaris
project meant to move the
Solaris-shy Linux
community off Linux and
on to Solaris tempted by
Solaris widgetry like the
highly scalable,
rollback-e 
At Java One this week Sun
has been selling its year
-old-but-still-upcoming -
and definitely
late-to-the-party - Adobe
AIR- and Microsoft
Silverlight-competitive
JavaFX Rich Client
environment as a
potential
revenue-generator capable
of putting ads on mobile
applications and JavaF
Mike Neil is general
manager for
virtualization strategy
in the Windows Server
Division at Microsoft.
Mike is focused on the
delivery of the Windows
virtualization
technology, including
Windows Server 2008
Hyper-V, Microsoft
Hyper-V Server and
Virtual PC 2007. Mike
also directs t
It's only taken Borland
two years but it's
finally dumped its
CodeGear tools division,
responsible for Borland's
hereditary JBuilder,
Delphi and C++ Builder
lines as well as its new
web ventures into PHP and
Ruby, said to be used by
7.5 million developers.
Embarcadero Technologie
