Code to explain the use of algorithms:<\/strong><\/p>\npackage com.DataFlair.CollectionFramework;\r\nimport java.util.*;\r\npublic class Algorithms\r\n{\r\n public static void main(String args[]) {\r\n LinkedList L1 = new LinkedList();\r\n L1.add(new Integer(15));\r\n L1.add(new Integer(2));\r\n L1.add(new Integer(-2));\r\n L1.add(new Integer(1000));\r\n Comparator r = Collections.reverseOrder();\r\n Collections.sort(L1, r);\r\n Iterator li = L1.iterator();\r\n System.out.print(\"List sorted in reverse: \");\r\n while(li.hasNext()) {\r\n System.out.print(li.next() + \" \");\r\n }\r\n System.out.println();\r\n Collections.shuffle(L1);\r\n li = L1.iterator();\r\n System.out.print(\"List shuffled: \");\r\n while(li.hasNext()) {\r\n System.out.print(li.next() + \" \");\r\n }\r\n System.out.println();\r\n System.out.println(\"Minimum: \" + Collections.min(L1));\r\n System.out.println(\"Maximum: \" + Collections.max(L1));\r\n }\r\n}\r\n\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nList sorted in reverse: 1000 15 2 -2
\nList shuffled: 15 -2 2 1000
\nMinimum: -2
\nMaximum: 1000<\/div>\n
As we can see, the use of algorithms can make programs short and simple.<\/p>\n
Java Iterator Interface in the Collection Framework<\/h3>\n
There is no point in storing data using collections if we can’t cycle through them. However, Java provides us with a very simple interface to do this, known as Iterator or ListIterator, depending on the type of collection that needs to be iterated. Moreover, an iterator enables you to cycle through a collection to obtain or remove elements.<\/p>\n
Moreover, ListIterator extends the Iterator interface to allow bidirectional traversal of a list and the modification of elements. However, these are very useful, especially in the case of various operations that require constant cycling through the list.<\/p>\n
Code to understand Iterator implementation:<\/strong><\/p>\npackage com.DataFlair.CollectionFramework;\r\nimport java.util.*;\r\npublic class Iterators\r\n{\r\n public static void main(String args[]) \r\n {\r\n ArrayList al = new ArrayList();\r\n al.add(\"D\");\r\n al.add(\"A\");\r\n al.add(\"T\");\r\n al.add(\"A\");\r\n al.add(\"F\");\r\n al.add(\"L\");\r\n al.add(\"A\");\r\n al.add(\"I\");\r\n al.add(\"R\");\r\n System.out.print(\"Original contents of al: \");\r\n Iterator itr = al.iterator();\r\n while(itr.hasNext()) {\r\n Object element = itr.next();\r\n System.out.print(element + \" \");\r\n }\r\n ListIterator litr = al.listIterator();\r\n while(litr.hasNext()) {\r\n Object element = litr.next();\r\n litr.set(element + \"+\");\r\n }\r\n System.out.print(\"\\nModified contents of al: \");\r\n itr = al.iterator();\r\n while(itr.hasNext()) {\r\n Object element = itr.next();\r\n System.out.print(element + \" \");\r\n }\r\n System.out.print(\"\\nModified list backwards: \"); \r\n while(litr.hasPrevious()) {\r\n Object element = litr.previous();\r\n System.out.print(element + \" \");\r\n }\r\n }\r\n}\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nOriginal contents of al: D A T A F L A I R
\nModified contents of al: D+ A+ T+ A+ F+ L+ A+ I+ R+
\nModified list backwards: R+ I+ A+ L+ F+ A+ T+ A+ D+<\/div>\n
Java Comparator Interface in Collection Framework<\/h3>\n
The comparator interface gives us the provision to compare two instances of a class or two elements in a collection of data. Hence, the Comparator interface consists of two methods: the compare method and the equals method.<\/p>\n
However, the Comparator Interface in Java enables developers to define the mechanism to sort the elements according to the requirement. However, the comparator interface then compares the values that are defined in the interface. Although, this interface is present in the java.util package.<\/p>\n
The compare method in Java:<\/h4>\nint compare(Object obj1, Object obj2)\r\n<\/pre>\nThe compare method returns:<\/strong><\/p>\n\n- negative if obj1 < obj2<\/li>\n
- zero if obj1 == obj2<\/li>\n
- positive if obj1 > obj2<\/li>\n<\/ul>\n
The equal method in Java:<\/h4>\nboolean equals(Object obj)\r\n<\/pre>\nHence, the equal() method returns true if the equality satisfies the object.<\/p>\n
Code to understand comparator implementation in Java:<\/strong><\/p>\npackage com.DataFlair.CollectionFramework;\r\nimport java.util.*;\r\nclass Dog implements Comparator<Dog>, Comparable<Dog> \r\n {\r\n private String name;\r\n private int age;\r\n Dog() {\r\n }\r\n Dog(String n, int a) {\r\n name = n;\r\n age = a;\r\n }\r\n public String getName() {\r\n return name;\r\n }\r\n public int getAge() {\r\n return age;\r\n }\r\n public int compareTo(Dog d) {\r\n return (this.name).compareTo(d.name);\r\n }\r\n public int compare(Dog d, Dog d1) {\r\n return d.age - d1.age;\r\n }\r\n}\r\npublic class Example {\r\n public static void main(String args[]) \r\n {\r\n List<Dog> list = new ArrayList<Dog>();\r\n list.add(new Dog(\"Scooby\", 3));\r\n list.add(new Dog(\"Bruno\", 2));\r\n list.add(new Dog(\"Oreo\", 10));\r\n list.add(new Dog(\"Darcy\", 4));\r\n list.add(new Dog(\"Tommy\", 1));\r\n Collections.sort(list);\r\n for(Dog a: list)\r\n System.out.print(a.getName() + \", \");\r\n Collections.sort(list, new Dog());\r\n System.out.println(\" \");\r\n for(Dog a: list) \r\n System.out.print(a.getName() +\" : \"+ a.getAge() + \", \");\r\n }\r\n}\r\n<\/pre>\nThe output of the above code:<\/strong><\/p>\nBruno, Darcy, Oreo, Scooby, Tommy,
\nTommy : 1, Bruno : 2, Scooby : 3, Darcy : 4, Oreo : 10,<\/div>\n
Advantages of Java Collection Framework<\/h3>\n
The Java Collection framework has several advantages, a few of which include:<\/p>\n
1. Consistent API:<\/strong> Java collection framework consists of a consistent API that has all the essential arrangements of interfaces like collections, Lists, Set, List, etc, and classes that implement the interfaces like ArrayList, Vector, etc.<\/p>\n2. Reduce Programming Exertion:<\/strong> The collection framework provides various provisions to implement an operation with ease, as a result, which helps the programmer to focus on the main task, rather than the basic operations.<\/p>\n3. Increases Program Quality and Speed:<\/strong> The collection Framework helps to increase the execution speed and quality by reducing program size and letting the programmer handle data with ease.<\/p>\nChoosing the Right Collection in Java<\/h3>\n
Picking the appropriate collection for your data structure is a vital step in working with the Java Collection Framework. Although there are some additional factors to consider when making your choice:<\/p>\n
1. Thread Safety:<\/strong> If your program involves multiple threads working with the same collection concurrently, you’ll need to consider thread safety. However, the Java Collection Framework offers thread-safe versions of some collection classes, such as ConcurrentHashMap and CopyOnWriteArrayList. Therefore, these classes ensure that data modifications by one thread won’t corrupt operations by another thread.<\/p>\n2. Iteration Needs:<\/strong> How you plan to iterate over your collection can also influence your decision. For example, if you need random access to elements, an ArrayList might be suitable. But if you only need to iterate in the order in which elements were added, a LinkedList could be more efficient.<\/p>\nConclusion<\/h3>\n
No doubt that the Java Collection Framework makes the programmer\u2019s task simpler. Not just that, by reducing the hassles of writing the operations manually, the Java framework enables programmers to solve bigger problems with ease. Therefore, this is the reason why the Java collection framework is so important. In this article, we saw the basic structure of the Java collection framework, as well as how to implement a few of the important methods.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the day-to-day life of a programmer, we are required to maintain a given set of data. Therefore, Java has different collections like lists, stacks, queues, etc., to maintain this set of data. However,...<\/p>\n","protected":false},"author":5,"featured_media":108835,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[32],"tags":[2634,2635,5638,7428,7589,7752],"class_list":["post-11882","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-java","tag-collection-in-java-with-examples","tag-collections-framework-in-java","tag-hierarchy-of-collection-framework-in-java","tag-java-collection-classes","tag-java-map-interface","tag-java-util-map"],"yoast_head":"\n
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![\"hierarchy](\"https:\/\/data-flair.training\/blogs\/wp-content\/uploads\/sites\/2\/2018\/03\/hierarchy-of-collection-framework-in-java.webp\")
<\/a><\/p>\n