List & Map

//Account a = new Account(name='Account14', Type='Prospect');

//Account b = new Account(name='Account15', Type='Prospect');

/*

//defining a list

Account [] accLst = new Account[]{a,b};

for(Account a : accLst){

System.debug(a.name);

}

System.debug(accLst[0].name);

*/

/*

//defining list

List<Account> actLst = new List<Account>{a,b};

for(Account a : actLst){

System.debug(a.name);

}

//defining list

List<Account> accs = [select name from Account];

//To add an object to the next available element of the List

accs.add(new Account(name='Account16'));

*/

/*

// Create a generic sObject variable.

List<sObject> sObj = Database.query('SELECT Id FROM Account LIMIT 1');

List<Account> aobjs = new List<Account>();

for(sObject a : sObj){

//typecasting generic object to Account Type

aobjs.add((Account)a);

}

for(Account at : aobjs){

System.debug(at.Id);

}

*/

Account a = new Account(name='Acme', BillingCity='New York');

Account b = new Account(name='Lakme', BillingCity='New Jersey');

Map<Integer, Account> mapAccount = new Map<Integer,Account>{};

mapAccount.put(1,a);

mapAccount.put(2,b);

//get the Account object mapped to key integer - 1

mapAccount.get(1).BillingCity='Mumbai';

//check the existence of a key

Boolean bo = mapAccount.containsKey(1);

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

//returns all keys that is stored in the Set object

keyInt = mapAccount.keySet();

for(Integer k : keyInt){

System.debug('keys are ' + k);

System.debug(mapAccount.get(k).name);

}

//Returns the number of key-value pairs in the map

System.debug(mapAccount.size());

//returns all values associated to the maps,

//in this instance all Account objects

System.debug(mapAccount.values());

for(Account a : mapAccount.values()){

System.debug(a.name);

}