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Which one is better when compare with Interface and Abstract class ?
muralidhar.9e
- Oct 30th, 2010
I prefer to Interface. Because the same feature can have different implementations in different Objects.And can also support for multiple Inheritance through Interfaces.If you go for Abstarct Classes ...
salman138
- Oct 29th, 2010
Both Interface and Abstract class have different usages. Interface is used to define that an object support a certain kind of functionality like any class that implements Comparable interface has the ...
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Class hierarchy of HashMap is as follows
"HashMap extends AbstractMap implements Map"
When AbstractMap implements Map interface and AbstractMap is extended by HashMap, what is the use of again implementing Map interface in the declaration of HashMap?.">Class hierarchy of AbstractMap is as follows "AbstractMap implements Map"Class hierarchy of HashMap is as follows "HashMap extends AbstractMap implements Map"When AbstractMap implements Map interface and AbstractMap is extended by HashMap, what is the use of again implementing Map interface in the declaration of HashMap?.
jimmy514in
- Oct 30th, 2010
When you create a concrete class, all the features of abstract classes & interfaces extended earlier have to be implemented, if not already done so..so that purpose of implementing an hashmap again doesnt really suffice the need..please let me know too..
neelam
- Jul 4th, 2006
This is because AbstractMap is the abstract class and not all methods from Map interface are implemented in AbstractMap. Hence HashMap implements Map interface to implement?of the metods in Map interface.
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Scope Variables
jimmy514in
- Oct 30th, 2010
owever the declaration of a member needs to appear before it is used when the use is in a member initialization expression...this is not correct..!!
satyarajasekhar
- Jun 11th, 2006
A variable's scope is the region of a program within which the variable can be referred to by its simple name. The location of the variable declaration within your program establishes its scope and pl...
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Downcasting - Superclass Reference
Explain what is superclass reference to subclass object? Why do we go for downcasting?
muralidhar.9e
- Oct 29th, 2010
Downcasting means using the super class object into the subclass.And we are cating to our sub class object.Like let's assume super and sub classesclass BaseClass{ ---...
manoj.muthavarapu
- Oct 27th, 2010
We extend a class to provide a more specialized behavior for it in the subclass. For example, consider the class "Vehicle" and imagine a subclass "Bus". All vehicle objects are cap...
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What significance of protected Constructors?
jimmy514in
- Oct 27th, 2010
And , I thought constructors were NOT inherited..what probably protected means , is that private..you cannot directly call that constructor..I am unsure, if you can use protected and inherit..please clarify1
jimmy514in
- Oct 27th, 2010
What if I have a scenario?public class A{protected A(String str){//code block}public A(){this("name1");}public static void main(){new A();//now you can use the protected constructor..//or you can also use the static block to call the protected constructor..cant u?}}
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Create Object Using Clone
Give an example of using clone to create an object.
muralidhar.9e
- Oct 11th, 2010
We can create an object by using clone() method which is a object class method.Create an object like MyClass obj=new MyClass();CloneClass cloneobj=(CloneClass)obj.clone();By this way you can create a ...
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What is the difference between abstraction, encapsulation and data hiding?
VishnuPrasad88
- Oct 4th, 2010
1. Encapsulation means Binding the Data with its relative functions. That means only those functions can access the data, and no other function can access that data. This can be achieved by classifyin...
lhariPrasad
- Mar 18th, 2008
Venkat,The thing which you mentioned can also be done by Inheritance, then what is the need of Abstraction over here in Java. Is it that much important ?I feel Abstraction is something where a specific template like structure is created for the implementators, aiming to provide a common interface.
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What are the Non access modifiers?
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Please give me answer why we use Interface though it contain only blank implementation.
muralidhar.9e
- Sep 20th, 2010
An Interface may Contain implementation or not. Sometimes these type of interfaces (blank interfaces) which are not implemented are called as "marker interfaces".
nikhil_52001
- Sep 19th, 2010
The purpose of Marker interface is to just let the compiler know that the clas which implements the Marker Interface will be serialized or cloned. Ther is not any other use of Marker Interface. E.g If...
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Remove() method collection
Which Underlying Collection will provide the remove() method?
rariedel
- May 28th, 2008
Collection is an interface, and whatever class implements the interface must implement the remove() method.This question is not a complete sentence and that makes it kind of difficult to understand the intent and then answer it appropriately.
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WeakHashMap
Explain how a WeakHashMap works?
aryadipan
- Sep 19th, 2010
You put an entry in a WeakHashMap with the object as the key, and the extra information as the map value. Then, as long as you keep a strong reference to the object, you will be able to check the m...
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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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J2EE Code Standards
What are the code standard used in J2EE project in real time?
thimothyarani
- Sep 16th, 2010
Give proper name for the variable, it has to describe it functions or process. Follow coding standards
Sriram_Geek
- Aug 15th, 2010
1) Give meaningful comments.2) Give meaning variable names.3) Use lazy initialization of variables that is declare them as and when needed. Need not declare variables upfront like in C.4) Make sure yo...
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How to create own Marker Interface with example
nagarajcse82
- Nov 28th, 2005
1.>in general tagged or marker interface is used to just identify the class, in real time projects there are so many classes,in order to identify which class belongs to which module,this tag or mar...
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What is the order of intialization of variables in Java.
muralidhar.9e
- Sep 8th, 2010
In Java the variable initialization should be in order. The order is: 1. Static block variables initialize at first 2. Static method of variables initialize second 3. Static variables initial...
sampra
- Feb 15th, 2008
First of all declare a memory block according to data typeassign var nameinitite by def valuewassign orignal value
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ReadLine() Function
Explain readLine function in Core Java.
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omkar.raj- Member Since Jul-2010 | Jul 8th, 2010
ReadLine() function is used to take the input from user in string format.
muralidhar.9e
- Sep 8th, 2010
Actually the readLine() method will reads the data through the bufferdReader object. It reads only one line of data through keyboard. We can't enter the multiple lines of data at runtime.This is the main functionality of the readLine() method.
sailendra.n.jena
- Aug 26th, 2010
It will read the data from the keyboard but line by line not character by character.
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What are some alternatives to inheritance?
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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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IBM Interview Questions in Bangalore
Br />1.what is oracle.2.what is major differenece oracle8i and oracle9i.4.tell me some thing ur self.5.please tell me about oops.6.what is single inheritance.7.what is multiple inheritance.8.can java support multiple inheritance.9.what is interface.10.what is differenec between abstract class and interface.11.how to u prove that abstrace class cannot instantiate directly.12.what is differenece between...
sujain
- Aug 17th, 2010
5. About OOPS: Object Oriented Programming is based on three major concepts: Inheritance, Polymorphism and Encapsulation Inheritance: Through inheritance the base class properties are acquired in subc...
anithananduri
- Aug 28th, 2009
8.can java support multiple inheritance.java support multiple inheritance for interfaces not fro classes25.what is difference between procedure and functions.function returns only one value where as procedure returns more than one value
Core Java Interview Questions
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