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Can HashMap store null values?If yes, how many and in which one?
vikas singh
- Dec 23rd, 2006
hi your ans is too good.........
santh kumar
- Dec 13th, 2006
I entered clearly. with spaces and next lines.Why i'm getting data collabarated? it is not easy to read. any suggestions would be appreciated. what should i do to be in the same format exactly how i entered. with regards, santh
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Restrict a Class
How can we restrict a class so that no instance creation of class possible without declaring the class as Abstract ?
Sarje
- Aug 18th, 2009
Only abstract classes can not be instantiated. If you make the constructor private then you can not instantiate it outside of the class but you can still instantiate it within the same class.
sriragv
- Jun 21st, 2009
1. By creating a private constructor2. By giving abstract key word to the class
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What would happen if you say this = null
ajkush
- May 6th, 2009
If the value is null or zero, the difference is simple as difference between I know and I dont know.Null means I dont know the value and zero means I know the value.
ashokkumar
- Jan 25th, 2007
[root@tm1 classes]# javac -d . ../../../src/com/tm/slynx/util/AuditLogBean.java../../../src/com/tm/slynx/util/AuditLogBean.java:47: cannot assign a value to final variable thisthis = null;^1 error
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How does serialization work
Sarje
- Aug 28th, 2009
In serialization process first state of the object is written to the java.io.ObjectOutputStream using its writeObject() method.Then this ObjectOutputStream writes the state of the object to the java.i...
sampra
- Feb 14th, 2008
It convert data object into flat format and transfer it any other remote mechine by any medum and thn there reconstruction of object will be done
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How would you pass a java integer by reference to another function
Mayank
- Mar 13th, 2018
I don't think that is right because if it was then changing the value inside the called function should reflect the change when the passed variable is accessed in calling function.
sourabharvikar3
- May 4th, 2011
what is point behind sending integer by reference???Still if you want to do so... lookclass Demo{private int i;public static void main(String[] ar){ Demo d=new Demo();&nb...
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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]);}
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Wrapping an Object
What does "wrapping" an object mean?
SreerangKulkarni
- Oct 29th, 2009
When an object A is said to "Wrap" object B, it means that Object A HAS A reference to the Object B and deligates calls to it.
karthik_knight2000
- Dec 3rd, 2008
Wrapping an object means we are covering that object, say for example? in Java we can say?String is a class as well as?String is a data type.String s;?? // here s is object of String class ???...
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What is the use of interface in realtime java project ?
Manjunath_7_89
- Mar 25th, 2016
Interface is majorly supported for IS-A relationship ie; Inheritance. Writing an interface is similar to writing a class. But a class describes the attributes and behaviours of an object. And an inter...
meena
- Feb 16th, 2016
Consider a construction of a building. The basic entire PLAN of the building I what an INTERFACE does. Next, the implementation of that PLAN is done by CONCRETE methods. If some of the work is done and still some is left is what ABSTRACT method/class does.
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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...
Core Java Interview Questions
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