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Dart Concepts

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Topics

  • Inheritance
  • Getters & Setters
  • Abstract Class & Methods
  • Generics
  • Safety Operators
  • Async

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Comments

  • Dart supports single-line comments, multi-line comments, and documentation comments.
  • Single-line comments
    • A single-line comment begins with //. Everything between // and the end of line is ignored by the Dart compiler.

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Comments

  • Multi-line comments
    • A multi-line comment begins with /* and ends with */. Everything between /* and */ is ignored by the Dart compiler (unless the comment is a documentation comment; see the next section).

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Getters and Setters

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  • Getters and Setters, also called as accessors and mutators, allow the program to initialize and retrieve the values of class fields respectively.
  • Getters or accessors are defined using the get keyword.
  • Setters or mutators are defined using the set keyword.

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Getters and Setters

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Getters and Setters

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Getters and Setters

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Getters & Setters

  • Syntax: Defining a getter

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Syntax: Defining a setter

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Sample Code

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Inheritance

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Class Inheritance

  • A class inherits from another class using the ‘extends’ keyword.
  • Child classes inherit all properties and methods except constructors from the parent class.

Syntax

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Types of Inheritance

Inheritance can be of the following three types −

  • Single − Every class can at the most extend from one parent class.
  • Multiple − A class can inherit from multiple classes. Dart doesn’t support multiple inheritance.
  • Multi-level − A class can inherit from another child class.

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Sample Code

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SAMPLE CODE

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Abstract Methods

  • Abstract methods can only exist in abstract classes.
  • To make a method abstract ,use semicolon ( ; ) instead of method body
  • Abstract Method can only exist with Abstract class

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Abstract Classes

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  • Use abstract keyword to declare abstract Class.
  • Abstract class can have Abstract Methods,normal Methods & Instance Variables as well.

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Syntax for defining Abstract Class

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abstract class class_name

{

//Body of Abstract Class

}

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Enumerated Types

  • Enumerated types, often called enumerations or enums, are a special kind of class used to represent a fixed number of constant values.
  • By default, the value of the first enumeration symbol is 0.
  • Declare an enumerated type using the enum keyword:

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Generics

  • Generics are often required for type safety.
  • The <…> notation marks List as a generic (or parameterized) type—a type that has formal type parameters.
  • The type is List<E>

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Sample Code

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Typedef

  • A typedef, or a function-type alias, helps to define pointers to executable code within memory.
  • Simply put, a typedef can be used as a pointer that references a function.

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Safety Operators

  • Collectively known as null-aware operators, these new features will help you reduce the code required to work with potentially null objects.

??

Use ?? when you want to evaluate and return an expression IFF another expression resolves to null.

exp ?? otherExp

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Safety Operators

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??=

Use ??= when you want to assign a value to an object IFF that object is null. Otherwise, return the object.

obj ??= value

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Safety Operators

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?.

Use ?. when you want to call a method/getter on an object IFF that object is not null (otherwise, return null).

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obj?.method()

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Static Keyword

  • The Static keyword can be applied to the data members of the class ,i.e fields & methods.

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Async

  • An asynchronous operation executes in a thread, separate from the main application thread.
  • When an application calls a method to perform an operation asynchronously, the application can continue executing while the asynchronous method performs its task.

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Create a contact.txt file as given below and save it in the current project.

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Future

  • The Dart community defines a Future as "a means for getting a value sometime in the future." Simply put, Future.
  • Dart is a single-threaded programming language. If any code blocks the thread of execution , the program effectively freezes.
  • Asynchronous operations let your program run without getting blocked. Dart uses Future objects to represent asynchronous operations.

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Classes

A class encapsulates data for the object.

Generics

Generics are often required for type safety, Properly specifying generic types results in better generated code & You can use generics to reduce code duplication.

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Safety Operators

Collectively known as null-aware operators, these features will help to reduce the code required to work with potentially null objects.

Typedefs

​

A typedef, or a function-type alias, helps to define pointers to executable code within memory.

​

Asynchrony support

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​

An asynchronous operation executes in a thread, separate from the main application thread.

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Classes

A class encapsulates data for the object.

Generics

Generics are often required for type safety, Properly specifying generic types results in better generated code & You can use generics to reduce code duplication.

​

Safety Operators

Collectively known as null-aware operators, these features will help to reduce the code required to work with potentially null objects.

Typedefs

​

A typedef, or a function-type alias, helps to define pointers to executable code within memory.

​

Asynchrony support

​

​

An asynchronous operation executes in a thread, separate from the main application thread.

​

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Classes

A class encapsulates data for the object.

Generics

Generics are often required for type safety, Properly specifying generic types results in better generated code & You can use generics to reduce code duplication.

​

Safety Operators

Collectively known as null-aware operators, these features will help to reduce the code required to work with potentially null objects.

Typedefs

​

A typedef, or a function-type alias, helps to define pointers to executable code within memory.

​

Asynchrony support

​

​

An asynchronous operation executes in a thread, separate from the main application thread.

​

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Classes

A class encapsulates data for the object.

Generics

Generics are often required for type safety, Properly specifying generic types results in better generated code & You can use generics to reduce code duplication.

​

Safety Operators

Collectively known as null-aware operators, these features will help to reduce the code required to work with potentially null objects.

Typedefs

​

A typedef, or a function-type alias, helps to define pointers to executable code within memory.

​

Asynchrony support

​

​

An asynchronous operation executes in a thread, separate from the main application thread.

​

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Classes

A class encapsulates data for the object.

Generics

Generics are often required for type safety, Properly specifying generic types results in better generated code & You can use generics to reduce code duplication.

​

Safety Operators

Collectively known as null-aware operators, these features will help to reduce the code required to work with potentially null objects.

Typedefs

​

A typedef, or a function-type alias, helps to define pointers to executable code within memory.

​

Asynchrony support

​

​

An asynchronous operation executes in a thread, separate from the main application thread.

​

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Comments

Dart supports single-line comments, multi-line comments, and documentation comments.

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Enum

Enums are a special kind of class used to represent a fixed number of constant values.

​

​

Getters & Setters

allow the program to initialize and retrieve the values of class fields respectively.

​

Inheritance

​

Inheritance means that a class can directly inherit from one class to another.

​

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Comments

Dart supports single-line comments, multi-line comments, and documentation comments.

​

Enum

Enums are a special kind of class used to represent a fixed number of constant values.

​

​

Getters & Setters

allow the program to initialize and retrieve the values of class fields respectively.

​

Inheritance

​

Inheritance means that a class can directly inherit from one class to another.

​

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Comments

Dart supports single-line comments, multi-line comments, and documentation comments.

​

Enum

Enums are a special kind of class used to represent a fixed number of constant values.

​

​

Getters & Setters

allow the program to initialize and retrieve the values of class fields respectively.

​

Inheritance

​

Inheritance means that a class can directly inherit from one class to another.

​

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Comments

Dart supports single-line comments, multi-line comments, and documentation comments.

​

Enum

Enums are a special kind of class used to represent a fixed number of constant values.

​

​

Getters & Setters

allow the program to initialize and retrieve the values of class fields respectively.

​

Inheritance

​

Inheritance means that a class can directly inherit from one class to another.

​

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