HashMap and Hashtable both implement java.util.Map interface but there are some differences that Java developers must understand to write more efficient code.
1)One of the major differences between HashMap and Hashtable is that HashMap is non-synchronized whereas Hashtable...
Friday, 22 August 2014
Thursday, 21 August 2014
Java Collections - Map
Map is an interface which is not derived from Collections interface as described in our previous post Java Collections. Map follows its own hierarchy .
It stores a key -value pair in which key should be unique and value can be anything related.
We use put method to store key-value pair in Map.
Can...
Sorting of ArrayList
Sorting of an array list is one of main tasks of a developer. There are mainly two ways to sort an array list.
1. Using natural order
2. Using Comparator interface .
For both methods we will use sort () method which is defined in Collections utility class.
See :
How to reverse a string in java
How...
Wednesday, 20 August 2014
Java Collections -Set
Set a Collection used to store Unordered but unique elements.
If you try to store a duplicat element in a set it will throw an error.
Example of set
Set setA = new HashSet();
String element = "element 1";
setA.add(element);
System.out.println( set.contains(element) );
Implemenation of set
Since...
Tuesday, 19 August 2014
How to iterate through list in java
List is a collection in java used to store Ordered objects which can be duplicate. List can be used to store either primitive data type or instances of a defined class. how to store object /instance...
How Objects are stored in heap and Stack in java
HEAP AND STACK IN JAVA
1. Stack is memory in computer which is used to store temporary information.
For eg. variables are stored on stack.
2.Information after the method is done with its...
Saturday, 16 August 2014
How to add List to another List
How to reverse a string in java
package test;
import java.util.ArrayList;
import java.util.List;
import java.util.ListIterator;
public class MainS {
/* we have two lists as l and b and will add and reterieve list l to b */
public static void main(String[] args) {
List l= new ArrayList();
...
How to add instance of a class to list and then retrieve it
Suppose we have a class Car with 2 properties Car model and car name.
We want to add instances of this class to a list so that later we can retrieve it.
See :
How to sort an Array List without using Comparator or sort method
Overriding/method Overriding In java
Difference between Application...
List in java Collection
List :
It is an interface inheritd from Collections for ordered collection of objects.
It can contain duplicate elements.
How is ArrayList different from Array?
ArrayList
Array
Is not definite in size. Can expand according to requirement.
Is definite in size.
Stores objects
Store primitive...
Java Collections- Everything you want to know
Collection is an interface - is a framework which allows for using and manipulating collections.
Set- A collection that cannot contain duplicate elements.
2. Elements are in unordered manner.
List-...
Thursday, 14 August 2014
Hibernate Interview Questions
1. Call Back Interfaces
These interfaces are helpful to receive notifications about changing state of an object such as saved , loaded , deleted.
There is no need to implement callback interfaces in hibernate.
See :How to sort an Array List without using Comparator or sort method
2. which...
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