Batch apex code samples with solution

                                                  Batch class Scenario



 1. Write a batch class to send a mail to all the related contacts where Account revenue is greater than 10000?

ANS:

   public with sharing class BatchclassforPractice implements Database.Batchable<sObject>,Database.Stateful {

    Global  Integer count=0;

    public List<String> conlist = new List<String>();

    public Database.QueryLocator start(Databse.BatchableContext bc)

    {

        return Database.getQueryLocator('select id from Account where revenue >10000');

   

    }

    public void execute(Databse.BatchableContext bc,List<Account> acclist)

    {  

        for(Account acc : acclist)

        {

            acclist1.add(acc.id);

        }

        for(contact con :[select id from contact where Account in : acclist1])

        {

            conlist.add(con.Email);

        }

    }

    public void finish(Database.BatchableContext bc)

    {  

        List<Messaging.SingleEmailMessage>Emaillist = new List<Messaging.SingleEmailMessage>();

        Messaging.SingleEmailMessage  message = new Messaging.SingleEmailMessage();

        message.setToAddresses(conlist);

        message.setSubject('Record is created');

        message.setPlainTextBody('your account revenue is greater than 10000 ');

        Emaillist.add(message);

        Messaging.sendEmail(Emaillist);

    }

}

Execute a batch class :

    BatchclassforPractice bc =  new BatchclassforPractice();

    databse.executeBatch(bc);