Apex Intermediate Progress | ( Lessons)

Lesson: 09 | Constructions

Notes

In Apex, a constructor is a special method that gets called when an object of a class is instantiated (created). The purpose of a constructor is to initialize the state of the object.

In other words, a constructor is used to set the initial values of the instance variables of a class when an object of that class is created.

A constructor has the same name as the class it belongs to and does not have a return type.

In Apex, there are two types of constructors:

Default Constructor: If you do not define any constructor in a class, then Apex automatically creates a default constructor with no arguments. This constructor does not do anything except initializing the instance variables to their default values.
Parameterized Constructor: A parameterized constructor is a constructor that takes one or more parameters. It allows you to initialize the instance variables of the object with the values passed as arguments to the constructor.

For example, consider the following Apex class with a parameterized constructor:

public class Person {
    public String name;
    public Integer age;

    public Person(String name, Integer age) {
        this.name = name;
        this.age = age;
    }
}

public class Demo {
  Integer x;  


  public   Demo() {
    x = 5;  
  }

  public static void myMethod() {
    Demo myObj = new Demo();
    System.debug(myObj.x); 
  }
}

Note that the constructor name must match the class name, and it cannot have a return type (like void).

Constructor can have parameters:

public class Demo {
  Integer x;

  public Demo(Integer y) {
    x = 2* y;
  }

  public static void myMethod() {
    Demo myObj = new Demo(5);
    System.debug(myObj.x);
  }
}

Exercises

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Apex Intermediate

A. Apex DML Operations (8 lessons)

B. Apex Classes (17 lessons)

C. Apex Triggers (9 lessons)

D. Apex Exceptions (11 lessons)

E. Asynchronous Apex (6 lessons)

F. SOSL (10 lessons)

G. Testing Apex (9 lessons)

H. Apex Fast Recap (142 lessons)

I. Build Apex Coding Skills (64 lessons)

J. Miscellaneous (17 lessons)

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Lesson: 09 | Constructions

Notes

Constructor can have parameters:

Apex Intermediate