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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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Arrays/Linked List
When and on what conditions will you decide whether to use linked lists or arrays, also Which process is fastest and which is slowest in arrays as well as linked list i.e, sorting, searching, add, delete etc.
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Aqan12- Member Since Apr-2010 | Jun 13th, 2010
Memory:
When you create an array you allocate all the memory while initializing the array, so if you had an array of 1000 Objects, you'd allocate space to hold 1000 object references as soon as you initialize the array.LinkedList on the other hand extends dynamically as the objects are added to the linked list.
Accessing Elements:
Arrays are useful if you are going to access elements using the index. if you need to access the 100th element you can directly access it by a[100].To access 100th element in a LinkedList you'll have to traverse 99 elements to reach the 100th element.
LinkedList can handle addition/deletion of elements better then arrays and that's one of the most powerful feature of LL over arrays.
Adding/Inserting Elements:
Array is fixed size; to add a number of elements greater then the size of the array you'd have to copy the array into a new bigger array.To insert an element in the middle of an array all the elements after the inserted element would have to moved up one index.
LinkedList can grow dynamically.
Deleting Elements:
To delete an element from Array you'd have to move down all the elements after the deleted element.LinkedList elements can be deleted dynamically.
To summarize, LinkedList can handle manipulation of data structure much better and efficiently manage memory but arrays have better accessibility when accessing elements by index.
Search and Sort would be similar performance on both.jamesjohnney
- Aug 12th, 2010
In all way Linked list is best then Arrays, since its a next level of Array 1. Linked list is dynamic allocation where as Arrays are not 2. We can get and set the value with the use of get, set method...
Anubhavs
- Aug 6th, 2010
Linked list is best under the feature of the manipulation e.g. insertion, deletion etc. In the other way the array will go through a good way if we focus on the accessibility.
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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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How do you declare constant values in java
rohitrichhariya
- Jul 23rd, 2010
For declaring constant in Java, Java gives us 3 suggestion.1. Declare constant variable as a final.2. Also constant variable declare as a final.3. All the letter of constant variable is capital....
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What is the practical use of volatile / transient modifiers?
naresh17201
- Jul 21st, 2010
Transient variables are can not be serialized. So it is used in the serialization process.In serilization object, some field is marked as transient,will not be transmitted in the byte stream.eg..file ...
mharivardhan
- Jul 15th, 2010
Volatile: In a multithreaded scenario when a shared variable value is modified by Thread1 might not be immediately updated to main memory. When Thread2 reads, it will get the old value. You...
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Abstract vs Interface Class
Which is faster at class loading - interface or abstract class? Why?
deshmukhcv
- Jul 12th, 2010
I will give the Answer with Example : Where to use Abstrace Class ::Suppose I am having class Animal. and Dog Class and Cat Class. Animal Class having method eat(). In eat() I will writ...
abhijeetsingh
- Jan 27th, 2010
In both cases differences will be negligible. It only depends upon our designing to use which one.
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What is the meaning of System.out.println(). How it is constructed?
satvant sandhu
- Jul 4th, 2010
System is only class which intracts with hardware and out is static reference variable of PrintStream class and println() is a method of PrintStream class.it's construction is like that...class&nb...
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In Java, how are objects / values passed around
nnandurkar
- Jun 23rd, 2010
Java supports only pass by value. If it is a primitive then copy of the value is passed. And if it is an object then copy of its reference is passed.
sampra
- Feb 20th, 2008
In Java Object are passed by reference and Primitive data is always pass by value
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Object Class Methods
Why wait() and notify() are used only for threads, why not to objects?
kalaiselvigurusamy
- Jun 11th, 2010
The wait() and notify() methods are object-specific. The wait() method suspends the current thread of execution, and tells the object to keep track of the suspended thread. The notify() method tells t...
jeetu1607
- May 30th, 2010
wait(), notify() and notifyAll() are in Object class because the lock for these are set on a object and these can be called on any object. Any threads accessing the object will be put into wait status...
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Serialization Process
Explain the use of serialization process in real time projects?
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Sarje- Member Since Aug-2009 | Aug 28th, 2009
Serialization is the process of writing the state of an object to a byte stream. This is useful when you want to save the state of the object (content of the object) to a persistent storage area, such a file.
For example if you want to maintain record of the temprature on a particular place at every hour then you can serialize your object and save the temprature at every hour in a file.
Only an object that implements the java.io.Serializable interface can be saved.dh_maan
- Jun 6th, 2010
The use of serialization process in real time project is to transfer the object over the network.
winoth4
- Oct 28th, 2009
Serialization is writing the state of the object to a byte stream. This is useful when you want to save the state of the object in a persistent ?storage such as file.
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When you have an object passed to a method and when the object is reassigned to a different one, then is the original reference lost
Aqan12
- Jun 4th, 2010
Primitives are always passed by value.Objects: Passed by value of reference. i.e. a copy of reference is passed into the method. Any changes to the reference itself will not be visible outside the met...
Scorpio_
- May 7th, 2010
Mr Ashutosh Gupta,Java is pass-by-value. For primitives, you pass a copy of the actual value. For references to objects, you pass a copy of the reference. You never pass the object. All objects are stored on the heap. Always http://www.javaranch.com/campfire/StoryPassBy.jsp
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Market interface means interface which have no methods. Then why we call the Runnable interface as a marker interface, even though it has run() method
pdommara
- May 31st, 2010
Who said Runnable interface is marker interface. It has method called run(). It is not a marker interface.
piscesinblues
- Jan 22nd, 2007
Up to my knowledge marker interface is an interface having no methods, so Runnable interface is an interface having run() method, so definetly it is not a marker interface, if so the case, please post the complete description regarding that and let me know
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Exception on finalize ()?
If Exception occurs in finalize() what happened to garbage collector? It will run or not? Explain
asanse
- May 27th, 2010
Any exception thrown by finalize() during garbage collection halts the finalization but is otherwise ignored.
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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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1)what are the other ways to create an object otherthan creating as new object?
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Why java does not have multiple inheritance?but in c++ ?
jimmy514in
- Apr 22nd, 2010
Multiple inheritance in Java is supported by the use of Interfaces.You do not have direct multiple inheritance because Java is a programming language which is kept simple.And using multiple inheritanc...
ashish_setia
- Oct 2nd, 2006
yes this is absoluetly true, in java we dont hav multiple inhet. actually multiple inheritance means a drive class is having mare than one base class. just as it will create the popular diomound probl...
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Mutithreading
How synchronization can be done for multithreading environment without using the "synchronized" keyword?
Aqan12
- Apr 13th, 2010
Use java.util.concurrent package Lock mylock;try{ mylock.lock(); //critical section}finally{ mylock.unlock();} Also: try a lock with a timeout trylock() wait for some condition: condition.await() these could come handy to avoid the deadlock situations.
kvrprasadmca
- Apr 7th, 2010
We can achieve by using thread-safe collection objects like vector and all.
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Whether a Class,Method can be garbage collected or not?How?
MMK143
- Mar 28th, 2010
Class and Method are not garbage collected because class and methods are the predefined instruction formats for developing an object oriented programming.
umesh_kilkile
- Mar 23rd, 2010
No. Class and methods aren't garbage collected.Because Class is a logical construct in that we write methods or logics.When we run Java program, class gets loaded in main memory that is RAM and method...
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Explain Servlet and JSP life cycle
nalindascjp
- Mar 4th, 2010
A Servlet is a Java class which faclitates a web developer to write dynemic web pages. JSP is the presentation componant that used with Servlets to make a page dynamic. Generally a JSP is a HTML docum...
sripatnaiky
- Feb 4th, 2010
Life cycles are pretty same, as the JSP will be translated into a servlet during the translation phase, the important point to be considered here is if we include another JSP by making use o...
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How many JVM's we can run in a system?
phanibhushan.g
- Mar 12th, 2010
We can run as many JVMs as possible at the same time depending on the memory (RAM). Also the JVM instance can belong to any one of the java implementors like Sun JDK, JRockit etc parallely. For using ...
mytramesh
- Apr 7th, 2006
Hai Friends you have to remember one thing.The Jvm is one.Butwe can have mamy jvm instances. you open five commmand prompts and do java programs in all command prompts.All will execute.For ...
Core Java Interview Questions
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