Constructor

Constructor:- 

  Constructor is a special method which have the following properties.

• Method name will be the same as class.
• Access specifiers will be Public.
• This method will invoked only once that is at the time of creating ab object.
• This is used to instance the data members of the class.

Ex:

        Public class Testobject

          {

                 // The no argument constructor

                

                Public Testobject()

                      {

                           // code

                                   }

                   }

There are 3 types of constructors,.

1. Default Constructor
2. Non-parameterized constructor     
3. Parameterized Constructor.          

1.Default Constructor:-  

             If an Apex class doesnt contain any constructor then Apex compiler b default creates a                       dummy constructor on the name of class when we create an object for the class.

  Ex: Public class Example

           {

         

                 }

      Example e=new Example();

  In the above example the apex class doesn't contain any constructor. so when we create object for example class Apex compiler creates a default constructor.

     Ex: Public class Example()

           {

         

                 }

2. Non-Parameterized Constructor & parameterized constructor:-

      It is a constructor that doesn't have any parameters, or  constructor that has parameters.

 Ex: Public class Example

           {

           Integer rno;
            string name;

                 }
     Public Example(Integer x, String myname )
           {
          rno=x;
          name=myname;
                 }

          Public Example( )
          {
             //code r.no=10;
                        name=sam;
              }
         }

write a Apex programm to demonstrate usage of constructor.

• Open developer console by clicking the name on the salesforce page.
• click file & select Apx clas.
• enter the class name.
• write the Apex class.'

Ex: 

       Public class Employee

          {

         String EmployeeName;

         Integer Employee no;

  

       Public Employee( )

  {

          EmployeeName='Hari';

          Employeno      = 10;

            }

         Public Void show( )

   {

      system.debug('EmployeeName is' +EmployeeName);

      system.debug('Employee is'   +EmployeeNo);

         }

  }

5.Open the anonymous block.

        Employee e1=new Employee( );

         Employee e2= new Employee( );

          e1.show( );            

          e2.show(;

 This will give an output of Employee Name is Hari and Empployee no is 10.

           

                                   EmployeeName is Hari

                                   EmployeeNo 10.