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How can I swap two variables without using a third variable?Can u plz tell me the logic behind it..?
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What is a Singleton class, what is it\'s significance? Thanks in advance!
rams_k
- May 10th, 2006
if we dont wnat a class to be subclassed or only one obj to be created go for singletone it only allows only one obj to be createdand rest of them to use that obj for examplePublic Class Singleton {&n...
Guest
- Mar 22nd, 2006
Hi All,Generally Singleton Pattern is used while accessing database related objects. It provides one point access to whole java application. It makes sense to make it thread safe by use of synchronized keyword. Regards-ashruf
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Why we cannot define constructor of super class in a sub class ?
sampra
- Feb 15th, 2008
We cannot define constructor of super class in subclass because the order of execution of constructors will be from super class to current class. So there is no need of defining the super class constructor in subclass.
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How to check infinity value? when we passed too large number in String and cast in to float value it will be give infinity. how to catch it?
jay
- Sep 23rd, 2006
Why not just treat infinty like any other String->float conversion error ? :float myfloat;try { myfloat = Float.parseFloat(floatAsString);} catch (Exception e) { // o-o the format of floatAsString is not quite compatible with java float}
Thakkar Nirav
- Apr 29th, 2006
Hi ,Finally i got the answer, but thank u all to give me prompt reply.i am using jdk1.4 . thats why i cant use Float.isInfinity() but i'll remember so in future i can use.thank u again.
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How to writer String Reverse program without using any string libraries even length(), strrev().
Y_NOT_
- Feb 6th, 2007
public class ReverseString{ public ReverseString() { String str = "Hello World"; StringBuffer buff = new StringBuffer( str ); buff.reverse(); System.out.println( "Reversed String: " + buff.toString() ); } public static void main( String[] args ) { new ReverseString(); }}
subramanian_ram
- Jan 3rd, 2007
public static void main(String args[]){String s1=" Mera Bharat Mahan";String s2="";int lenght = 0;for(int i=0;s1.charAt(i) != null;i++) length++;for(j=length; j<0;j++){ s2=s2+s1.charAt(j);}System.out.println("the reverse string is"+ s2);}}
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Marker interface having no methods right.. then what is the use of marker interface? for what purpose we use marker interface?
One of the "clean" features of the Java programming language is that it mandates a separation between interfaces (pure behavior) and classes (state and behavior). Interfaces are used in Java to specify the behavior of derived classes. Often you will come across interfaces in Java that have no behavior. In other words, they are just empty interface definitions. These are known as marker interfaces....
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When does the String Literal pool gets cleared?
In one java class I have created this string String s1 = "abc";Now if I again use this same statement in a different java class, ie;String s2 = "abc";Will I get the same reference for "abc" in both the classes.
adarsh
- Jul 30th, 2012
"c public class stringreferencetest { public static void main(String[] args) { String s1 = "abc"; class AnotherClassString { String s2=""; public AnotherClassString() {...
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What is the difference between dynamic method dispatch and method over riding?
vinaymudgil007
- Jun 9th, 2008
Sampra -- what you said is correct but don't you think that over-ridding itself uses dynamic method dispatch....what i am trying to say is that the line demarcation is very thin.vinny
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What are advantages and usage of static block?
pdommara
- May 28th, 2010
The above answers are missing important point that is it even runs before your class constructor.
vinaymudgil007
- Jun 10th, 2008
static block is executed whenever a class is loaded by the JVM.....hence in case you want certain code to executed or say some objects of a class avaliable to ur application as soon as the application starts you can put in the relevant code there....vinny
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What is the use of writing empty catch block?
vinaymudgil007
- Jul 31st, 2008
Just catch the exception & swallow it [don't take any action].that's all.vinay
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Will there be a performance penalty if you make a method synchronized? If so, can you make any design changes to improve the performance
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Editorial / Best Answer
Answered by: Faisal Ghauri
- Jul 24th, 2005
Performance does take a hit when using synchronization. I think the way to reduce this hit is to synchronize only a block of code that will be accessed by threads and not synchronize the entire method.
sumeesudha
- Feb 6th, 2010
There is degradation in performance when you make a method synchronized. Even when a program contains only a single thread running on a single processor, a synchronized method call is still slow...
sripatnaiky
- Feb 4th, 2010
The Synchronization may be useful in avoiding the deadlock, helpful in maintaining the consistent object state etc,. Only one thread will be accessed at a time by acquiring lock on the synchronized bl...
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Differences between HashList and HashMap, Set and List
nnandurkar
- Jun 23rd, 2010
Hashtable is syncronised where as HashMap is not. Hence, HashMap is faster.Hasttable does not allow any null value as either key or value. However, HashMap allows multiple null values and one nul...
kayalsuku
- Jun 2nd, 2008
HashMap is an unordered and unsorted map. Allow one null key and many null values. Lists are collections that maintain their elements in order, and can contain duplicates. Set interface do not a...
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What is data encapsulation? What does it buy you
ragini.rani
- Mar 13th, 2006
encapsulation mean data hiding.data correspond to varibles and methods of the class. Data hiding mean: when u make different objects of the same class. The data stored in one object is unaware of the data for other object of the same class. In, this way it gives secure data.
Devidas Sonawane
- Oct 28th, 2005
Encapsulation:- it is a mechanism to binds data and bytecodes and b'coz of that data is protected and becomes secure.
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Would you like to derive data from a base class
biman786
- Aug 14th, 2010
If the Base class and super class are within same package, then data of super class should be public or default or protected. But if base and super classes are in different packages, then?then data of super class should be public or protected.
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What is the Difference between Design Pattern and Architecture? Can any one answer for this plz..
Design Pattern means how u r approaching the problem.Architecture means how the data is flowing in your application
sambitsahu
- Jan 5th, 2010
Design Pattern:A design pattern suggests a solution for a recurring design problem in an application and the solution is generally open for future extensions.Architecture:It's an outline of an app...
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Why ArrayList is faster than Vector?
meSubhadip
- Jul 21st, 2009
Vector is synchronized so JVM needs to take extra care to acquire and release locks to make vector thread safe. But ArrayList is not synchronized so JVM doesn't need this extra overhead.That's why arraylist is faster than vector.
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What is the difference between Enumeration and Iterator?. When i can use Enumeration and when i can use iterator?. Can any one tell me the situation that only Enumeration could able to solve that problem and vice versa.
In Enumeration we cant modify the elements. where as in iterator we can modify the elements
guls.naikwadi
- Dec 27th, 2009
Both are used to traverse objects one by one but Enumeration is a legacy classes and it comes with Java1.1 Iterater they have introduced in Collection framework. Enumeration can be used for Coll...
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How can u tell HashTable is Synchronized?(IBM-chennai)
John
- Apr 3rd, 2007
HashTable is synchronized
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Core Java Interview Questions
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