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What is the difference between Static and Dynamic Polymorphisim?
pradeep_gupta49
- Sep 16th, 2010
First of all I am telling about Polymorphism Polymorphism: The term polymorphism was defined from the greek 'Poly' and 'morphos' which mean 'many' and 'forms'. Poly+Morphos=Many forms Polymorph...
bhaumiklitu
- Jan 5th, 2009
The term static polymorphism is associated with overloaded methods because it gives the impression that a single named method will accept a number of different argument types. The System.out.println()...
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What type of access specifiers can we use for local variables?
Sarje
- Aug 18th, 2009
Local variable cannot be modified using any of the acceess specifiers means you can not write private or protected or public before them.Local variables are by default (implicitly)? private no need to make it explicitly private or protected or public otherwise it won't compile.
er.mukesh_208
- Aug 3rd, 2008
Local variables (including formal parameters) are visible only in the method, constructor, or block in which they are declared. Access modifiers (private, public, ...) can not be used with local var...
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Is SQLException run time or compile time exception?
timmireddy
- Jul 14th, 2008
SQLexception that is thrown when SQL Server returns a warning or error. This class cannot be inherited. SQLException comes under Runtime exception because errors comes under Unchecked Exceptions.
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What is the result of expression 5.45 + "3.2"?
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Null keyword
Is null a keyword? if not what is it?
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interviewprep9- Member Since Jun-2008 | Jun 14th, 2008
Capital N, Null is not a keyword or a reserved word.
All small letters, null is not a keyword either. but, it's a reserved word. you cannot use null as follows:
String null = "a";
null means that a reference is not pointing to any object.
Sarje
- Aug 17th, 2009
Null is not a keyword but null is reserved literal. null is the default value for instance variable.String str = null;means instance variable str does not hold reference of any object.
varmasuman
- Sep 13th, 2008
Null?means showing nothingWhenever one object reference refers null i.e? ServletConfig application=null;Then there is nothing in the object reference application.
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Usage of Abstract class and Interfaces
In Real time when we go for Abstract classes and when we go for Interfaces
Sarje
- Aug 13th, 2009
If you want to create only abstract methods in a class then use interface and if you want to create some of the methods as abstract and some as concrete then use abstract class.
dyy123
- Nov 14th, 2008
When you don't want to expose the implementation of the methods then you can use the Interface. Abstract class is will have some methods implemented and some unimplemented.
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Static data member
What is the use of static data member?
Sarje
- Aug 13th, 2009
Static data members field (variable) and method belong to class. Static fields can be used before creating an instance of the class and static method can be accessed using class name.
aditya_8584
- Mar 24th, 2009
Static data member has a class scope. A single copy of static data member get shared?within the objects of that class. A non-static member cannot access a static member of that class.
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Need of Polymorphism
What is need of polymorphism in Java? What could have happen if polymorphism is not present?
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syamala235- Member Since Mar-2010 | Apr 8th, 2010
Polymorphism in simple terms means one name many forms. Polymorphism enables one entity to be used as a general category for different types of actions. The specific action is determined by the exact nature of the situation.
Polymorphism exists in three distinct forms in Java:
• Method overloading
• Method overriding through inheritance
• Method overriding through the Java interfacePrashant kumar gupta
- Oct 28th, 2017
We have different behaviors in different situations and in front of different people. A man behaves differently with his father, when he is with his friend he has different behavior. Another best exa...
suraj
- Jun 19th, 2017
Polymorphism means one thing in many form. or one person different behavior is called polymorphism.
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What is the purpose of interface? And tell the difference between the class and interface?
sachin
- Aug 2nd, 2011
interface is mainly used to achieve standardization and loose coupling.. Its like a media between two systems. Interface can be treated like rules, where only method definition is present but not imp...
surya_merla
- Jun 7th, 2009
An interface is a specification of method prototypes. All the methods of interface are public and abstract. They are public because they should be available to third party vendors and they are abstrac...
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How to Synchronize the HashMap
Any Body Tell about this
pitu2000
- Aug 21st, 2010
After introduction of concurrency api in Java 1.5 we have one more way to synchronize a hashmap>> new java.util.concurrent.ConcurrentHashMap(hashmapObj);
EshaPrasad
- Apr 21st, 2009
We can do as given belowHashMap hm = new HashMap(); HashMap hm2 = (HashMap)Collections.synchronizedMap(hm); ArrayList a1 = new ArrayList(); ArrayList a2 = (ArrayList)Collections.synchronizedList(...
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String s1=s+"World";
S.O.P(s1); means printing "HelloWorld".How ?">Strings are immutable.But String s="Hello"; String s1=s+"World"; S.O.P(s1); means printing "HelloWorld".How ?
Amit Khaware
- Jun 17th, 2011
String s = "Hello"; means one object with value "Hello" will be created in the heap and reference variable s will refer to the object.but whenString s1 = s+"World";w...
talktoatish
- Aug 15th, 2009
Very tricky question.Asked me in Oracle interview for 4 years level of expHere is the answer: When JVM see the code where two three string objects has been added with + operator then it is using the S...
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I want to know output of this program and the flow alsopublic class Aquestion { private int i = giveMeJ(); private int j = 10; private int giveMeJ() { return j; } public static void main(String args[]) { System.out.println((new Aquestion()).i); } }
talktoatish
- Aug 16th, 2009
public class Foo { private static int j = 10; private static int i = giveMeJ(); private static int giveMeJ() { System.out.println("in the method" + i + j); return j; } public static void...
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What are the primitive types in Java
sampra
- Feb 14th, 2008
primtive datatyp is non object datatypeint chat short byte long float double boolean
teju
- Nov 5th, 2007
Primitive type means .int char double float string single long .............
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Is there a separate stack for each thread in Java
Sandip shelke
- Aug 10th, 2015
Yes there is separate stack for each thread.
Bcoz suppose i have created two thread & I am writing a for loop in run method
which incrment from 1 to 10
void run()
{
for(int i=1;ihannarani
- Apr 3rd, 2008
Yes. Every thread maintains its own separate stack, called Runtime Stack but they share the same memory. Elements of the stack are the method invocations, called activation records or stack frame. The activation record contains pertinent information about a method like local variables.
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When you use a struts framework, where would you place your business logic
Debananadajena
- Jul 16th, 2008
When we are using struts the action class should not contain the business logic if we are adding in action class then it is not right because action class are instantiated by controller.So we can use ...
shaik subhani
- Dec 18th, 2007
When we want to develop complex applications , you can use struts framework.Strtus framework is based on MVC architecture. Actually we have model classes to develop businesslogic .you can access model classes from execute() method of Action class
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What are the other ways to prevent a class from being subclassed.one way is to declare the class final.does declaring a class private prevent it from being subclassed?
vinaymudgil007
- May 21st, 2008
Pankaj Vishwani.....your code is compiling because you have prefixed the kerword void before the constructor of stud class...... hence its not a constructor anymore.... its beheaving like a method as ...
Ram
- Jan 8th, 2007
Well pankaj. The deal is to make the constructor private. In your example you have created a method as private as constructor do not have any return type. So try compiling again. cheers. Ram
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What is the difference between equals and ==?
sanika.desao
- Feb 27th, 2008
Equals compares two objects whereas == compares two memory locations thus comparing the values at memory locations.
sampra
- Feb 22nd, 2008
The difference b/w .equals and == is the comparision b/w object when using .equals and when using == its comparision of values b/w two. but some time it compare content some time address in the case of string it compare content
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Static methods are override or overload ?
vinaymudgil007
- Jun 12th, 2008
Guys to my knowledge..... we can overload but can't override static methodsvinny
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Jumble Array Values
An array A is of size N. Write a java method that jumbles all values in the array. All possible permutations must be possible and chances for each possible permutation must be equal. For example, size of array A is 3. A[0]=x, A[1]=y, A[2] =z.Possible permutations are 3! After jumbling elements, there would be equal chances for each of xyz,yxz,... to be in the array elements.
n_ulthi
- Aug 6th, 2010
public class Shuffle { // swaps array elements i and j public static void swap(String[] a, int i, int j) { String swap = a...
sandeep aulakh
- Dec 2nd, 2009
Class jumble{public stativ void main(String aa[]){int a[]=[1,2,3];for(i=0;i<3;i++)for(j=0;j<3;j++){a[i][j]=a[j][i];}System.out.println("the result is"+a[i][j]);}
Core Java Interview Questions
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