Basic To Advanced Selenium Java Full Course - Session 4 - Handling Exceptions, Collections Framework

Handling Exceptions: An exception is an unexpected event that disrupts the normal flow of program Types of Java Exception: Checked Exception - These exceptions are checked at compile time. Ex: IOException, SQLException Unchecked Exception - These exceptions are checked at run time. Ex: ArithmeticException, Null Pointer Exception, ArrayIndexOutOfBoundsException Exception Handling can be performed by using the below keywords: try - Code which is expected to return exceptions can be placed inside try block catch - It contains the code which is used to handle the exception finally - Code which must execute whether or not exception occurs is kept in finally block throw - It is used to throw an exception throws - If a method throws an exception it must be declared by using throws keyword Collections: Collection is an object which represents a group of objects Collections framework is a unified architecture for representing and manipulating collections Collections can be used to perform all operations on data like sorting, insertion, manipulation and deletion Reduces programming efforts by providing in built algorithms and data structures Increases performance by providing high performance implementations of data structures and algorithms Increases code reuse by providing standard interface for collections and algorithms Array List: ArrayList is a dynamic array for storing elements Elements can be added and removed easily from a array list It can contain duplicate elements It maintains the insertion order of the elements Methods: add() To insert specific element in specific position clear() To remove all elements from the list get() To fetch element from particular position in the list set() To change the element in the list remove() To remove the first occurrence of specified element size() To return the elements present in the list indexOf() To get index of first occurrence of an element in the list HashMap: It stores the data in key value pairs where keys should be unique It can contain one null key but multiple null values It doesn’t maintain order of elements It is non synchronized i.e. multiple threads can access it simultaneously It uses a technique called Hashing which converts a large string to small string that represents the same string. A shorter value helps in indexing and faster searches HashMap Methods: get() Returns the value associated with specified key put() Used to insert an entry in the map isEmpty() Returns true if map contains no key value mappings Remove() Used to delete an entry for the specified key containsKey() Returns true if the specified key exists in the map containsValue() Returns true if the specified value exists in the map equals() Used to compare an object with map clear() Used to remove all mappings from the map entrySet() Returns a Set view of mappings contained in the map keyset() Returns a Set view of the keys contained in the map HashSet: It implements the Set interface Uses Hash Table to store data Duplicate values are not allowed Insertion order is not maintained Null values are allowed It is non synchronized HashSet Methods: add() Used to add the specified element to the set if it is not already present clear() Used to remove all elements from the set contains() Returns true if set contains the specified element size() Returns the number of elements in the set isEmpty() Returns true if the set contains no elements To enquire more about Selenium Java Trainings, please contact us at [email protected]