Collections

MAP

public with sharing class MapUsage {

       

        public static void mapUse(){

       

            Map<Integer, String> mp = new Map<Integer, String>();

            // kEy is Integer

            // value is String

           

            mp.put(1221,'Mahi');

            //mp.put(1226,'Shyam');

            mp.put(1211,'Rajesh');

            mp.put(1255,'Kiran');

           

            System.debug('---------------Elements in the map are ------------>'+mp);

            System.debug('---------------Size of the map is-------4---------->'+mp.size());

            System.debug('------------Keys in the map are ----------->'+mp.keyset());

            System.debug('------------Values in the map are ----------->'+mp.values());

           

            System.debug('------------------'+mp.get(1211));

           

            mp.remove(1226);

           

            mp.put(1211,'Charan');

            mp.put(1248,'Pavan');

            mp.put(1222,'Kiran');

           

            System.debug('---------------Elements in the map are ------------>'+mp);

            System.debug('---------------Size of the map is-------5---------->'+mp.size());

           

            for(Integer i : mp.keyset()){

                System.debug('-----Key--------'+i);

                System.debug('-----value---------'+mp.get(i));

            }

           

            for(String s: mp.values()){

                System.debug('----------------'+s);

            }

           

        }       

}

SET

Set usage in APEX:

public with sharing class SetUsage {

   

    public void setUse(){

       

        Set<Integer> st = new Set<Integer>();

       

        st.add(1234);

        st.add(1248);

        st.add(1225);

        st.add(1252);

       

        System.debug('----------------Elementa in the set are --------------'+st);

        System.debug('----------------Size of Elementa in the set are ------4--------'+st.size());

       

        st.remove(1252);

        System.debug('----------------Size of Elementa after removing an element in the set are ------3--------'+st.size());

       

       

        st.add(1248);

        st.add(1252);

        st.add(1221);

        System.debug('----------------Size of Elementa in the set after adding duplciates are ------5--------'+st.size());     

       

        Set<Integer> newst = st.clone();

        System.debug('----------------Size of Elementa in the new set are -------5-------'+newst.size());

       

        st.clear();

        System.debug('-----------------NEw set is EMpty or not--------false--------'+newst.isEmpty());

       

        for(Integer i: newst){

            System.debug('----------------->'+i);

        }       

    }

   

}

LIST

public with sharing class ListUsage {

       

        public void listUse(){

           

            // Initialising a list

            List<String> lst = new List<String>();

           

            // Adding elemenst into list

            lst.add('ABC');

            lst.add('DEF');

            lst.add('GHI');

            lst.add('JKL');

           

            System.debug('---------Elements in the list are-------------->'+lst);

            System.debug('----------Size of the Elements are-----4-------->'+lst.size());

            System.debug('-----------Element in 2nd index--------GHI-------->'+lst[2]);

            lst.remove(1);

            System.debug('---------Elements in the list after removing are-------------->'+lst);

            System.debug('----------Size of the Elements after removing are----3--------->'+lst.size());

           

            lst.add('MNO');

            lst.add('GHI');

            lst.add('DEF');

            lst.add('1248');

           

            System.debug('---------Elements in the list after adding duplicate values are-------------->'+lst);

            System.debug('----------Size of the Elements after adding duplicate values are--------7----->'+lst.size());

           

            List<String> newlst = lst.clone();

            System.debug('---------Elements in the new list are-------------->'+newlst);

            System.debug('----------Size of the Elements in new list are-------7------>'+newlst.size());

           

            lst.clear();// removes all the elements in the list

            System.debug('-----------------List is Empty or not-------true----------->'+lst.isEmpty());

            System.debug('-----------------New List is Empty or not-------false----------->'+newlst.isEmpty());

           

            //Indexing for loop

            for(integer i=0; i<newlst.size(); i++){

                System.debug('-----Index------->'+newlst[i]);

            }

           

            //For Each Loop

            for(String s: newlst){

                System.debug('-----For Each---------->'+s);

            }

           

           

        }

       

       

       

}