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Showing posts with label Selenium 2. Show all posts
Showing posts with label Selenium 2. Show all posts

  • PriorityQueue Class is one of the collection framework class which implements Queue, Serializable, Iterable and Collection interfaces.
  • It is using natural ordering to order then elements of PriorityQueue.Or elements will be ordered based on Comparator provided at queue construction time depending on which constructor is used.
  • PriorityQueue is based on a priority heap. Heap is tree based data structure where all the nodes of tree are in a specific order. Please read about Heap to learn how it works.
  • PriorityQueue does not allow non-comparable objects and it may throw ClassCastException if you will try to do so.
  • PriorityQueue does not allow null elements as well.
  • PriorityQueue implementation is not synchronized. So multiple threads should not access it concurrently.
Java PriorityQueue Class

  • If you look at collection hierarchy, Queue extends collection interface.
  • Main purpose of collection is to hold the elements prior to processing.
  • Queue interface provides some additional operations like insertion, inspection and extraction besides collection interface operations.
  • All these three operations exist in 2 different forms. One return special value(null or false depending on the operation) if operation fails else throws an exception if operation fails.
  • Queue follows FIFO(first-in-first-out) so it will insert element at the end of the queue when you insert new element and element will be removed from the beginning of the queue when you remove element.
  • As Queue interface is sub type of collection interface, all methods of collection interface are also available in Queue interface.
Queue Interface hierarchy

  • Stack class in java is one of the collection interface class which is subclass of Vector class.
  • Stake class supports usual push and pop operations.
  • In contrast to queue, Stack class has last-in first-out(LIFO) data structure. So item which is inserted at top will be available first.
  • Stack class extends Vector class of List interface so it includes all methods of vector class and also it has it's own several methods to perform push and pop operations like looking top item from stack, removing top item from stack, push new item at top of stack, searching item from stack and check whether stack is empty.
java stack class example

  • Vector class in java implements List interface of collection framework.
  • Vector class is synchronized.
  • If you don't know size of array then you can use vector class as size of vector can grow and shrink as per adding and removing items.
  • As vector class is synchronized, It will give poor performance on add, delete, update and search operations.
  • Elements of vector can be accessed using it's integer index.
vector class hierarchy in java

  • LinkedList class extends AbstractList class.
  • LinkedList class implements List and Deque interfaces.
  • LinkedList class is using doubly linked list to store elements in list.
  • LinkedList can hold duplicate elements in list.
  • LinkedList is non synchronized.
  • Manipulation is faster in linkedlist as shifting is not required when new element is inserted or deleted from list.
  • You can use it as list, stack or queue as it implements List and Deque interfaces of collection framework.

  • ArrayList class is sub class of collection interface which implements to List interface.
  • ArrayList class provides resizable-array so it can grow automatically as per requirement which resolves fixed Array limitation where you have to pre-define the size of array.
  • It can hold null elements too.
  • It is not synchronized implementation so if multiple threads accessing it concurrently and any one from them modifies the entry then it must be synchronized externally.
  • Also it can hold duplicate elements.
Java ArrayList Class hierarchy

What is Java Collections Framework?
Java Collections Framework is group of different interfaces, classes and algorithms. In simple word, Collection means single unit of objects and framework means good architecture. It is best architecture to store group of reusable objects and manipulate them. Collection framework has many different interfaces, their sub interfaces and classes, their classes and sub classes. All the interfaces and classes has different purpose. You can perform add, edit, delete, search, sort, etc operations on group of objects as per class's methods and implementation.

Java Collections Framework

Main Advantages Of Collection Framework
  • Main advantage of collection framework is it will reduces your programming efforts as there are ready made interfaces, classes and their methods which you can use directly in your program to perform operation on object collection. 
  • Collection is well structure framework so you code quality and speed will be increased.
  • Anyone can use collection very easily as it's interfaces, classes and methods very easy to understand and use.
Interfaces and Classes of Collection Framework
Collection, Set, List, Queue, Deque, SortedSet, Map and SortedMap are core interfaces of collection framework. Detailed description of collection framework's interfaces and it's classes is given on below given pages.


  • List interface in java is ordered collection so it can store elements in sequence.
  • List interface is sub interface and it extends to Collection interface.
  • List interface can hold duplicate elements so you can insert duplicate elements too.
  • You can access elements from list by integer index.
  • Collection framework has many interfaces in java and list interface is one of them.
  • List interface provides ListIterator to traverse through elements list in backward and forward directions.
List interface java

  • Collection is an interface in java.
  • Collection interface extends Iterable interface.
  • In hierarchy, Collection interface is root of List, Queue and Set interfaces.

Java Collection Interface

  • It represents unit of its elements. i.e. group of objects.
  • Some collections do not allow duplicate elements but some allows duplicate elements.
  • Collection interface is base on which collection framework is built.

Earlier have shared many tutorial examples on selenium IDE different commands and Its usage. You can view each of that example on Selenium IDE Tutorial. Still many peoples are using selenium IDE to automate their small web applications and sometimes they needs to perform compatibility testing In Google Chrome and IE browsers like submitting form, registration, login etc. activities.

We can perform these activities very easily In google chrome and IE browsers using Selenium WebDriver and you can view related tutorials link on Selenium Tutorial. Is It possible to run selenium IDE test In Google Chrome? Yes.. Follow steps given bellow to run selenium IDE test In google chrome browser.

Part 10

46 : What is Polymorphism?
Answer : Polymorphism is ability using which we can create reference variables or methods which behaves differently in different programmatic context. Best example of polymorphism is human. We behaves differently with different people in different environment. Our behavior will be different when we meet to boss and meet to friend. Read more on Polymorphism in java.

47 : What is the advantages of Polymorphism?
Answer : Main advantage of polymorphism is code reusabilty. You can dynamically supply different implementations through polymorphism. So it will reduce your work volume in terms of handling and distinguishing various objects.

Part 9

41 : In java, What is return type of main method?
Answer : Main method doesn't have any return type. It is void.

42 : Can We Overload main method in java?
Answer : Yes, Java class can have any number of main methods so it is possible to overload main method. But when you run program, It will not execute overloaded main method. Always It will execute only public static void main(String[] args) method.

Part 8

36 : What is the difference between the Constructor and Method?
Answer : Main difference between the Constructor and Method is as bellow.

Constructor :
  1. Name of the constructor must be same as class name.
  2. Constructor must not have any return type.
  3. It is used to initialize the state of an object.
  4. It is not possible to call constructor directly. Constructors called implicitly when the new keyword creates an object.
Method :
  1. Method name can be any.
  2. Method must have return type.
  3. It is used to expose behavior of an object.
  4. Methods can be called directly.
Read more on Constructor and Method.

Part 7

31 : What is default value of local variable.
Answer : There is not any default value of local variable. You must have to initialize it. View more details on local variables in java.

32 : Java support constructor inheritance?
Answer : No, Constructor inheritance is not supported in java. View more details on constructor in java.

Part 6

26 : What is local variable in java?
Answer : Local variable is declared inside method or constructor and it is limited for that method or constructor only. View more detail on local variable in java.

Local Variable Example :
public class JavaVariable {

 public void Calc() {
  // Local Variables.
  int sum;
  int item1 = 5;
  int item2 = 7;
  sum = item1 + item2;
  System.out.println("Sum is : " + sum);
 }

 public static void main(String args[]) {
  JavaVariable j = new JavaVariable();
  j.Calc();
 }
}

Earlier we have talked about method overriding concept in java during THIS POST to change the implementation of parent class's method in sub class. In inheritance, Super keyword is used to refer object of immediate parent class. Generally we are using super keyword in inheritance for three different purpose. Let's see how and when to use super keyword in java. Interviewer can ask you this question so please understand how it works.

This article is about, Run Test cases with automation scripts in test link. It is necessary that you had worked on selenium before. After wards only you will understand this still try to explore from below information.

There are some important points and Preconditions for this. You need to install Java first. Then install Eclipse. Give proper Path in environment variable for Java and Eclips.

Moving to Next, Install Junit 4.11 jar , Selenium Jar and Test Link client API jar.

Part 5

21 : Explain System.out.println();

Answer :
  • System : is a final class in  java.lang package.
  • out : is a static member of system class. It is an instance of java.io.PrintStream. This stream is already open and ready to accept output data.
  • println : is a method of java.io.PrintStream .It is an overloaded method.

Part 4

16 : Can we overload static methods? 

Answer : Yes.. There is not any restriction to overload static methods. We can overload static and non static methods in java. VIEW MORE on overloading in java.

Part 3

11 : Why main method is static?

Answer : As we know, We can access static stuff without creating object of class. Because of static keyword with main method, Java virtual machine can directly call it without creating object of class. This way it will provide kind of root to start execution of program.

12 : What is method overloading?

Answer : Method overloading is ability to create multiple methods with same in same class but with different signatures (different input parameters and types). Method names will be same but parameters will be different for all overloaded methods.