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5 Java Constructor Java Tutorial for Beginners
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Java Constructor | Java Tutorial for Beginners • About this Video: • In this video, • I have explained about Java Constructor in simple way. • Links: • To learn about basics of Java click here 👇 • • Java Tutorials for Beginners | Java c... • Java Method: • • #2 Method in Java | Java for Beginner... • Class and Object: • • #1 class and object in java | Java fo... • Why we need programming language: • • Why we need Programming Language? | J... • Notes: • 1.Why we need constructor in java? • 2.What is Constructor? • 3.Rules to write Constructor. • 4.Important Points to be remembered about Constructor. • 5.Types of Constructor. • 5.1 Default Constructor. • 5.2 No- argument • Constructor • 5.2.1 Syntax • 5.2.2 Access-modifiers for Constructor • 5.3 Parameterized Constructor • 5.3.1 Syntax • 1.Why we need constructor in java? • We need constructor to construct or to give values to an object's fields. • In other words, • Constructor is used to • initialize an object • 2. What is Constructor? • Constructor is a block of code which is used to construct or to give values to • an object's fields during creation of an object. • Or In other words, • Constructor is a place where • Object initialization takes place.. • And object initialization means to gives values to an object. • 3. Rules to write constructor • 1.Name of class and name of constructor must be same • That means. • 2. Constructor doesn't have any return type and this is the important difference between method and constructor. • Method compulsory has return type but constructor doesn't have any return type • 3.You can use access modifiers for constructor. • Such as public, private, protected and default. • That means, • Constructor can be public, private, protected and default. • 4.You can not use non access modifiers for constructor. • Such as, static,final, abstract and synchronised. • That means,Java constructor cannot be static,final, abstract and synchronised. • 4.Important points to be remembered about constructor. • 1.Constructor is not a method,it just look like a method. • So don't be confused • constructor is different thing and method is different thing. • 2.Constructor is use to give values to an object. • Constructor is not use to create an object. • So don't get confused. • Constructor is used for object initialization not for object creation. • Bcoz the meaning of constructor itself is to construct. • So constructor is used to construct values to an Object is the main purpose of constructor and new keyword is used to create an object. • So simply keep in mind. • Constructor is used for object initialization. • And new keyword is used for object creation. • 3.Constructor calling takes place at the time of object creation. • 5.Types of Constructor. • 5.1 Default Constructor • 5.2 No-Argument Constructor • 5.3 Parameterized Constructor • 5.1 Default constructor. • To give values to an object. • You have to write constructor in a class but,if you forget to write constructor in the class and directly create an object then what will happen. • So in this situation, compiler • automatically creates constructor with zero argument i.e no- argument and gives default values to an object. • So basically. • Default constructor is a constructor created by a compiler to initialize fields of an object with default values at the time of object creation. • And remember, • If you do not write any constructor in a program then compiler creates default constructor and if we write any constructor in program then compiler doesn't create any constructor. • 5.2 No - Argument Constructor • No - Argument Constructor is constructor that programmers need to create and it does not have any argument or parameters and hence it's called as No - Argument Constructor and it's also called as Non- Parameterized Constructor. • 5.2.1 Syntax : • access-modifier class name() { • // Code; • } • 5.2.2 AccessModifiers for constructor.. • Access modifiers controll the aceess level of Constructor.. • That means,you can declare constructor as public, private, protected and default • If you declare constructor as a public then constructor accessible in all classes in a program.. • In other words, • You can called constructor from any class in a program.. • And if you declare constructor as private then • constructor cannot be called from anywhere outside the class. • If constructor declare as protected then constructor can called within same package and outside of package. • If a constructor does not have any modifier • Then it's considered as a default modifier and in this case constructor can called only within its own package. • Now question is arrise that how we can call constructor right, • So constructor automatically get called at the time of object creation you do need to call it separately. • 3.Parameterized Constructor • Parameterized Constructor is Constructor that programmers need to create with parameters called as parameterized constructor. • 5.3.1 Syntax : • access- modifier class name(parm-list) { • // Code; • } • _______End_________ • Thanks for watching 🙏 • #javaconstructor #javaconstructorinreallife • #sgtutorial #english
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