{"id":4008,"date":"2020-12-10T19:18:15","date_gmt":"2020-12-10T13:48:15","guid":{"rendered":"https:\/\/cns72.com\/vytcdc.com.sg\/?p=4008"},"modified":"2020-12-10T20:45:16","modified_gmt":"2020-12-10T15:15:16","slug":"collections-in-java","status":"publish","type":"post","link":"https:\/\/cns72.com\/vytcdc.com.sg\/collections-in-java\/","title":{"rendered":"Collections Data-structure in Java"},"content":{"rendered":"
\n

Any group of individual objects which are represented as a single unit is known as the collection of the objects. In Java, a separate framework named the \u201cCollection Framework\u201d has been defined in JDK 1.2 which holds all the collection classes and interface in it.<\/p>\n

The Collection interface (java.util.Collection) and Map interface (java.util.Map) are the two main \u201croot\u201d interfaces of Java collection classes.<\/p>\n

\/\/import util package[all classes]<\/span>\r\nimport<\/span> java.<\/span>util<\/span>.<\/span>*;<\/span>\r\npublic<\/span> class<\/span> StartCode<\/span> {<\/span>\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"Welcome to code java collection framework\"<\/span>)<\/span>;<\/span>\r\n       \/*\r\n       creating collection\r\n       1)Type Safe- same type of elements(objects) are added to collection\r\n       2)Un Type safe- different types of elements can be added to collection\r\n        *\/<\/span>\r\n        \/\/Type safe collection<\/span>\r\n        ArrayList<\/span><<\/span>String<\/span>><\/span><\/span> names =<\/span> new<\/span> ArrayList<\/span><<\/span>String<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Abdul\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Sitara\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Roshni\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Vandna\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Vandna\"<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>names)<\/span>;<\/span>\r\n        \/\/get<\/span>\r\n\/\/        System.out.println(names.get(0));<\/span>\r\n\/\/        System.out.println(names.get(1));<\/span>\r\n        \/\/un type safe<\/span>\r\n\/\/        LinkedList list = new LinkedList();<\/span>\r\n\/\/        list.add(\"Sachin\");<\/span>\r\n\/\/        list.add(101);<\/span>\r\n\/\/        list.add(625.5124);<\/span>\r\n\/\/        list.add(true);<\/span>\r\n\/\/        System.out.println(list);<\/span>\r\n        \/\/remove<\/span>\r\n        names.<\/span>remove<\/span>(<\/span>\"Roshni\"<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>names)<\/span>;<\/span>\r\n        \/\/size<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"SIZE = \"<\/span> +<\/span> names.<\/span>size<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n        \/\/check item is there or not<\/span>\r\n        \/\/ Type ka equals method call karta hai checking karne ke lie<\/span>\r\n        \/\/Student<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>names.<\/span>contains<\/span>(<\/span>\"Durgesh Kumar\"<\/span>)<\/span>)<\/span>;<\/span>\r\n        \/\/check for empy<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>names.<\/span>isEmpty<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n        \/\/setting value..<\/span>\r\n        \/\/names.set(1,\"Ram\");<\/span>\r\n        names.<\/span>add<\/span>(<\/span>1<\/span>,<\/span> \"Ram\"<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>names)<\/span>;<\/span>\r\n        \/\/remove all elements<\/span>\r\n\/\/        names.clear();<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>names)<\/span>;<\/span>\r\n        Vector<\/span><<\/span>String<\/span>><\/span><\/span> vector =<\/span> new<\/span> Vector<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        vector.<\/span>addAll<\/span>(<\/span>names)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"VECTOR \"<\/span> +<\/span> vector)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"_____________________________________\"<\/span>)<\/span>;<\/span>\r\n        HashSet<\/span><<\/span>Double<\/span>><\/span><\/span> nms =<\/span> new<\/span> HashSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        nms.<\/span>add<\/span>(<\/span>14.14<\/span>)<\/span>;<\/span>\r\n        nms.<\/span>add<\/span>(<\/span>34.12354<\/span>)<\/span>;<\/span>\r\n        nms.<\/span>add<\/span>(<\/span>(<\/span>2354.235<\/span>)<\/span>)<\/span>;<\/span>\r\n        nms.<\/span>add<\/span>(<\/span>99.3<\/span>)<\/span>;<\/span>\r\n        nms.<\/span>add<\/span>(<\/span>99.3<\/span>)<\/span>;<\/span>\r\n        nms.<\/span>add<\/span>(<\/span>5.3<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>nms)<\/span>;<\/span>\r\n        TreeSet<\/span><<\/span>Double<\/span>><\/span><\/span> tset =<\/span> new<\/span> TreeSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        tset.<\/span>addAll<\/span>(<\/span>nms)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>tset)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span><\/code><\/pre>\n
\n
<\/div>\n<\/div>\n<\/div>\n
TraverseExample.java<\/b><\/p>\n
\n
import<\/span> java.<\/span>util<\/span>.<\/span>*;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span>function<\/span>.<\/span>Consumer<\/span>;<\/span>\r\npublic<\/span> class<\/span> TraverseExample<\/span> {<\/span>\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n        ArrayList<\/span><<\/span>String<\/span>><\/span><\/span> names =<\/span> new<\/span> ArrayList<\/span><<\/span>String<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Abdul\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Sitara\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Roshni\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Vandna\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"Vandna\"<\/span>)<\/span>;<\/span>\r\n        names.<\/span>add<\/span>(<\/span>\"ABC\"<\/span>)<\/span>;<\/span>\r\n        \/\/for each loop:<\/span>\r\n        for<\/span>(<\/span>String<\/span> str:<\/span>names)<\/span>\r\n        {<\/span>\r\n            System<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>str +<\/span>\"\\t\"<\/span>+<\/span>str.<\/span>length<\/span>(<\/span>)<\/span>+<\/span>\"\\t\"<\/span>)<\/span>;<\/span>\r\n            StringBuffer<\/span> br=<\/span>new<\/span> StringBuffer<\/span>(<\/span>str)<\/span>;<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>br.<\/span>reverse<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n        }<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"________________________\"<\/span>)<\/span>;<\/span>\r\n        \/\/traversing using ITERATOR: Forward traversing<\/span>\r\n        Iterator<\/span><<\/span>String<\/span>><\/span><\/span> itr =<\/span> names.<\/span>iterator<\/span>(<\/span>)<\/span>;<\/span>\r\n        while<\/span>(<\/span>itr.<\/span>hasNext<\/span>(<\/span>)<\/span>)<\/span>\r\n        {<\/span>\r\n            String<\/span> next =<\/span> itr.<\/span>next<\/span>(<\/span>)<\/span>;<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>next)<\/span>;<\/span>\r\n        }<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"+++++++++++++++++++++++\"<\/span>)<\/span>;<\/span>\r\n\r\n        \/\/backward traversal of collection LISTITERATOR<\/span>\r\n        ListIterator<\/span><<\/span>String<\/span>><\/span><\/span> litr =<\/span> names.<\/span>listIterator<\/span>(<\/span>names.<\/span>size<\/span>(<\/span>)<\/span>)<\/span>;<\/span>\r\n        while<\/span>(<\/span>litr.<\/span>hasPrevious<\/span>(<\/span>)<\/span>)<\/span>\r\n        {<\/span>\r\n            String<\/span> previous =<\/span> litr.<\/span>previous<\/span>(<\/span>)<\/span>;<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>previous)<\/span>;<\/span>\r\n        }<\/span>\r\n        \/\/Enumeration<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"++++++++FOR EACH METHOD+++++++++++++\"<\/span>)<\/span>;<\/span>\r\n        \/\/for each method<\/span>\r\n        names.<\/span>forEach<\/span>(<\/span>str-><\/span>{<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>str)<\/span>;<\/span>\r\n        }<\/span>)<\/span>;<\/span>\r\n\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>\"SORTING OF ELEMENTS\"<\/span>)<\/span>;<\/span>\r\n        TreeSet<\/span><<\/span>String<\/span>><\/span><\/span> set=<\/span>new<\/span> TreeSet<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n        set.<\/span>addAll<\/span>(<\/span>names)<\/span>;<\/span>\r\n        set.<\/span>forEach<\/span>(<\/span>e-><\/span>{<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>e)<\/span>;<\/span>\r\n        }<\/span>)<\/span>;<\/span>\r\n\/\/        Comparable<\/span>\r\n\/\/        Comparator<\/span>\r\n    }<\/span>\r\n}<\/span><\/code><\/pre>\n
\n
<\/div>\n<\/div>\n<\/div>\n
MapExample<\/b><\/p>\n
\n
import<\/span> java.<\/span>util<\/span>.<\/span>HashMap<\/span>;<\/span>\r\nimport<\/span> java.<\/span>util.<\/span>function<\/span>.<\/span>BiConsumer<\/span>;<\/span>\r\n\r\npublic<\/span> class<\/span> MapExample<\/span> {<\/span>\r\n    public<\/span> static<\/span> void<\/span> main<\/span>(<\/span>String<\/span>[<\/span>]<\/span> args)<\/span> {<\/span>\r\n\r\n        HashMap<\/span><<\/span>String<\/span>,<\/span>Integer<\/span>><\/span><\/span>  courses=<\/span>new<\/span> HashMap<\/span><<\/span>><\/span><\/span>(<\/span>)<\/span>;<\/span>\r\n\r\n        \/\/adding elements<\/span>\r\n        courses.<\/span>put<\/span>(<\/span>\"Core Java\"<\/span>,<\/span>4000<\/span>)<\/span>;<\/span>\r\n        courses.<\/span>put<\/span>(<\/span>\"Basic Python\"<\/span>,<\/span>3500<\/span>)<\/span>;<\/span>\r\n        courses.<\/span>put<\/span>(<\/span>\"Spring\"<\/span>,<\/span>8000<\/span>)<\/span>;<\/span>\r\n        courses.<\/span>put<\/span>(<\/span>\"Android\"<\/span>,<\/span>4000<\/span>)<\/span>;<\/span>\r\n        courses.<\/span>put<\/span>(<\/span>\"Android\"<\/span>,<\/span>6000<\/span>)<\/span>;<\/span>\r\n        courses.<\/span>put<\/span>(<\/span>\"PHP\"<\/span>,<\/span>2414<\/span>)<\/span>;<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>courses)<\/span>;<\/span>\r\n\/\/        courses.forEach((e1,e2)->{<\/span>\r\n\/\/            System.out.println(e1+\"=>\"+e2);<\/span>\r\n\/\/        });<\/span>\r\n        courses.<\/span>forEach<\/span>(<\/span>(<\/span>key,<\/span>value)<\/span>-><\/span>{<\/span>\r\n            System<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>key)<\/span>;<\/span>\r\n            System<\/span>.<\/span>out.<\/span>print<\/span>(<\/span>\"=>\"<\/span>)<\/span>;<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>value)<\/span>;<\/span>\r\n            System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>)<\/span>;<\/span>\r\n        }<\/span>)<\/span>;<\/span>\r\n        \/\/entry set<\/span>\r\n        \/\/key set<\/span>\r\n        System<\/span>.<\/span>out.<\/span>println<\/span>(<\/span>courses.<\/span>get<\/span>(<\/span>\"Core Java\"<\/span>)<\/span>)<\/span>;<\/span>\r\n    }<\/span>\r\n}<\/span><\/code><\/pre>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
Any group of individual objects which are represented as a single unit is known as the collection of the objects. In Java, a separate framework named the \u201cCollection Framework\u201d has been defined in JDK 1.2 which holds all the collection classes and interface in it. The Collection interface (java.util.Collection) and Map interface (java.util.Map) are the […]<\/p>\n","protected":false},"author":1,"featured_media":4011,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[63],"tags":[],"yoast_head":"\nCollections Data-structure in Java - TCDC<\/title>\n<link rel=\"canonical\" href=\"https:\/\/cns72.com\/vytcdc.com.sg\/collections-in-java\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Collections Data-structure in Java - TCDC\" \/>\n<meta property=\"og:description\" content=\"Any group of individual objects which are represented as a single unit is known as the collection of the objects. In Java, a separate framework named the \u201cCollection Framework\u201d has been defined in JDK 1.2 which holds all the collection classes and interface in it. 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