{"id":1045,"date":"2016-03-08T06:30:42","date_gmt":"2016-03-08T06:30:42","guid":{"rendered":"http:\/\/abhiandroid.com\/java\/?page_id=1045"},"modified":"2018-06-05T06:34:18","modified_gmt":"2018-06-05T06:34:18","slug":"linkedhashmap","status":"publish","type":"page","link":"https:\/\/abhiandroid.com\/java\/linkedhashmap","title":{"rendered":"LinkedHashMap Tutorial In Java With Example"},"content":{"rendered":"

LinkedHashMap is a type of Collection which takes all the functionalities of HashMap class\u00a0i.e.\u00a0it stores our data in a pair such that each element has a key associated with it. The pair of key and value is often known as Entry. As LinkedHashMap is sub-class of HashMap class so it also indirectly extends AbstractMap class and which further implements Map Interface.<\/p>\n

In Addition to all the functionalities of HashMap Class, the functionality of maintaining the insertion is added into LinkedHashMap and to attain this\u00a0 functionality all the entries(key and value) are linked to each other using doubly-linked list. This doubly-linked list maintains the iteration ordering, which is in general the order in which keys were added in the map.<\/p>\n

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Hierarchy of <\/strong>Linked<\/strong>HashMap class<\/strong><\/h4>\n

LinkedHashMap Class extends HashMap Class which further \u00a0extends AbstractMap Class and that Implements Map Interface as shown in following\u00a0 figure 1.<\/p>\n

Dotted arrow shows AbstractMap implements Map Interface and Bold Array shows \u00a0LinkedHashMap extends HashMap which further extends AbstractMap class.<\/p>\n

\"Hierarchy<\/center><\/p>\n
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\u00a0LinkedHashMap Methods in JAVA<\/strong><\/h4>\n

Let us discuss all the LinkedHashMap methods one by one with Examples in Java.<\/p>\n

1. void clear()<\/strong><\/span><\/p>\n

This method as the name suggests removes all the entries in the LinkedHashMap, as shown in the following program<\/p>\n

import java.util.LinkedHashMap;\r\n\r\nimport java.util.Map;\r\n\r\npublic class LinkedHashMapDemo {\r\n\r\npublic static void main(String[] args) {\r\n\r\nMap<String, Integer> linkedHashMapobject = new LinkedHashMap<String, Integer>();\r\n\r\nlinkedHashMapobject.put(\"Samsung Grand quattro price \", new Integer(10000));\r\n\r\nlinkedHashMapobject.put(\"Micromax canvas price\", new Integer(9000));\r\n\r\nlinkedHashMapobject.put(\"Sony T2 Ultra price\", new Integer(20000));\r\n\r\nlinkedHashMapobject.put(\"Nokia Lumia price\", new Integer(15000));\r\n\r\nlinkedHashMapobject.put(\"Microsoft Lumia price \", new Integer(16000));\r\n\r\n\/\/ Displaying the contents of the LinkedHashMap before usig clear method\r\n\r\nSystem.out.println(\"Contents of LinkedHashMap before clear method : \" +\r\n\r\nlinkedHashMapobject);\r\n\r\nlinkedHashMapobject.clear();\r\n\r\n\/\/Displaying the contents of the LinkedHashMap before usig clear method\r\n\r\nSystem.out.println(\"Contents of LinkedHashMap\u00a0 after clear method: \" +\r\n\r\nlinkedHashMapobject);\r\n}\r\n}\r\n<\/pre>\n
Output:<\/strong><\/span><\/p>\n
Contents of LinkedHashMap before clear method: {Samsung Grand quattro price =10000, Micromax canvas price=9000, Sony T2 Ultra price=20000, Nokia Lumia price=15000, Microsoft Lumia price =16000}\r\n\r\nContents of LinkedHashMap after clear method: {}\r\n<\/pre>\n
2. boolean containsKey(Object key)<\/strong><\/span><\/p>\n
This methods checks whether the key given in the argument list is present or not in the LinkedHashMap entries, as shown in the following program .<\/p>\n
import java.util.LinkedHashMap;\r\n\r\nimport java.util.Map;\r\n\r\npublic class LinkedHashMapDemo {\r\n\r\npublic static void main(String[] args) {\r\n\r\nMap<String, Integer> linkedHashMapobject = new LinkedHashMap<String, Integer>();\r\n\r\nlinkedHashMapobject.put(\"Samsung Grand quattro price \", new Integer(10000));\r\n\r\nlinkedHashMapobject.put(\"Micromax canvas price\", new Integer(9000));\r\n\r\nlinkedHashMapobject.put(\"Sony T2 Ultra price\", new Integer(20000));\r\n\r\nlinkedHashMapobject.put(\"Nokia Lumia price\", new Integer(15000));\r\n\r\nlinkedHashMapobject.put(\"Microsoft Lumia price \", new Integer(16000));\r\n\r\n\/\/ Displaying the contents of the LinkedHashMap before usig<\/u> clear method\r\n\r\nSystem.out<\/em>.println(\"Contents of LinkedHashMap before : \" + linkedHashMapobject);\r\n\r\n\/\/Checking whether Map contains a particular key\r\n\r\nSystem.out<\/em>.println(\"\\nLinkedHashMap contains 'Nokia Lumia price' as key? : \" + linkedHashMapobject.containsKey(\"Nokia Lumia price\"));\r\n}\r\n}\r\n<\/pre>\n
Output:<\/span><\/strong><\/p>\n
Contents of LinkedHashMap before : {Samsung Grand quattro price =10000, Micromax canvas price=9000, Sony T2 Ultra price=20000, Nokia Lumia price=15000, Microsoft Lumia price =16000}\r\n\r\nLinkedHashMap contains 'Nokia Lumia price' as key? : true\r\n<\/pre>\n
3. boolean containsValue(Object value)<\/strong><\/span><\/p>\n
This methods checks whether the value given in the argument list is present or not in the LinkedHashMap entries, as shown in the following program.<\/p>\n
import java.util.LinkedHashMap;\r\n\r\nimport java.util.Map;\r\n\r\npublic class LinkedHashMapDemo {\r\n\r\npublic static void main(String[] args) {\r\n\r\nMap<String, Integer> linkedHashMapobject = new LinkedHashMap<String, Integer>();\r\n\r\nlinkedHashMapobject.put(\"Samsung Grand quattro price \", new Integer(10000));\r\n\r\nlinkedHashMapobject.put(\"Micromax canvas price\", new Integer(9000));\r\n\r\nlinkedHashMapobject.put(\"Sony T2 Ultra price\", new Integer(20000));\r\n\r\nlinkedHashMapobject.put(\"Nokia Lumia price\", new Integer(15000));\r\n\r\nlinkedHashMapobject.put(\"Microsoft Lumia price \", new Integer(16000));\r\n\r\n\/\/ Displaying the contents of the LinkedHashMap before usig<\/u> clear method\r\n\r\nSystem.out<\/em>.println(\"Contents of LinkedHashMap before : \" + linkedHashMapobject);\r\n\r\n\/\/Checking whether Map contains a particular value\r\n\r\nSystem.out<\/em>.println(\"LinkedHashMap contains 16000 as value? : \" + linkedHashMapobject.containsValue(16000));\r\n}\r\n}\r\n<\/pre>\n
Output:<\/strong><\/span><\/p>\n
Contents of LinkedHashMap before : {Samsung Grand quattro price =10000, Micromax canvas price=9000, Sony T2 Ultra price=20000, Nokia Lumia price=15000, Microsoft Lumia price =16000}\r\n\r\nLinkedHashMap contains 16000 as value? : true\r\n<\/pre>\n
Read All LinkedHashMap\u00a0Methods in JAVA with Example<\/a><\/strong><\/p>\n
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Example of LinkedHashMap class<\/strong><\/h4>\n
Let us discuss Linked Hashmap class with the help of program, following program has been divided into 3 Steps that we will discuss one by one.<\/p>\n
import java.util.LinkedHashMap;\r\n\r\nimport java.util.Map;\r\n\r\npublic class LinkedHashMapDemo {\r\n\r\npublic static void main(String[] args) {\r\n\r\nMap<String, Integer> linkedHashMapobject = new LinkedHashMap<String, Integer>();\/\/ Step 1\r\n\r\nlinkedHashMapobject.put(\"Samsung Grand quattro price \", new Integer(10000)); \/\/ Step 2\r\n\r\nlinkedHashMapobject.put(\"Micromax canvas price\", new Integer(9000));\r\n\r\nlinkedHashMapobject.put(\"Sony T2 Ultra price\", new Integer(20000));\r\n\r\nlinkedHashMapobject.put(\"Nokia Lumia price\", new Integer(15000));\r\n\r\nlinkedHashMapobject.put(\"Microsoft Lumia price \", new Integer(16000));\r\n\r\nSystem.out.println(\"Contents of LinkedHashMap : \" + linkedHashMapobject); \/\/step 3 \r\n\r\nSystem.out.println(\"\\nValues of linkedHashMapobject after iterating over it : \\n\");\r\n\r\nfor (String key : linkedHashMapobject.keySet()) {\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0\u00a0 \/\/Step 4\r\n\r\nSystem.out.println(key + \u201c:\\t\u201d + linkedHashMapobject.get(key));\r\n}\r\n}\r\n}\r\n\r\n<\/pre>\n
Description of Example:<\/strong><\/span><\/p>\n