Using for-each loop is easier than constructing the iterator to iterate over the collection and can be used in most of the cases rather than using the iterator loop. Any collection which wants to be the target of the “for-each loop” statement has to implement iterable interface.
if you are using List interface any implementation that implements List interface can be swapped with the existing one. Reduced effort as framework already provides several implementations for most of the scenarios that can be used as-is.High performance, implementation of the Collection classes (ArrayList, LinkedList, HashSet etc.) are very efficient and used as-is in most of the cases.Benefits of the Collections Framework are – Java Collections Framework provides a standard way to handle a group of objects. What Is Java Collections Framework? What Are The Benefits Of Using Collections Framework? It has item variable for holding the value and two reference to Node class itself for connecting to next and previous nodes. Within the LinkedList implementation there is a private class Node which provides the structure for a node in a doubly linked list. LinkedList class in Java implements List and Deque interfaces and LinkedList implements it using doubly linkedlist. What Is Linkedlist Class In Java? How Is It Implemented? When we add an element to an ArrayList it first verifies whether it has that much capacity in the array to store new element or not, in case there is not then the new capacity is calculated which is 50% more than the old capacity and the array is increased by that much capacity (Actually uses pyOf which returns the original array increased to the new length) How Arraylist Works Internally In Java?īasic data structure used by ArrayList to store objects is an array of Object class, which is defined like – Performance wise HashMap is faster than the HashTable reason being HashMap is not synchronized.The iterator used for both HashMap and HashTable is fail-fast but the enumerator used with HashTable is fail-safe. For traversing a HashTable either an iterator or Enumerator can be used. For traversing a HashMap an iterator can be used.HashMap allows one null value as a key and any number of null values where as HashTable does not allow null values either as key or as value.HashMap is not synchronized where as HashTable is synchronized.But there are certain difference between the two –
Though both HashTable and HashMap store elements as a (key, value) pair and use hashing technique to store elements, moreover from Java v1.2, HashTable class was retrofitted to implement the Map interface, making it a member of the Java Collections Framework. Difference Between Hashmap And Hashtable In Java? LinkedHashSet should be used in this case. Which Set Implementation Should Be Used If You Want The Insertion Order To Be Maintained? To have a descending order either comparator has to be provided or reverseOrder method of the Collections class can be used.Ĭollections.sort(cityList, Collections.reverseOrder())
#JAVA COLLECTIONS QUESTIONS HOW TO#
How To Sort Arraylist Of Strings In Descending Order?Ĭollections.sort() method will sort the ArrayList of String in ascending order.
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