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DART Programming Language Summary Dart is a Object Oriented Language, its upports features like Classes, interfaces, etc. Dart is created by Google Inc. Important Definition: - //Class: is blueprint for objects. //Fields: are any variable defined in class. Fields represent Data applied to objects. //Setters and Getters allows the program to initialize the retrive the data of fields. //Constructors allocates memory for the object of the class. //Functions: Functions are actions that objects can perform. They at some times are called Methods. //Method is a action that an object can perform. //Instance of Class i.e use new key word followed by class name. syntax: var ObjName = new ClassName(argument); //Attributes and Functions can be accessed USING Object with dotnotation followed by attribute/function name. Syntax: ObjName.fieldName; Syntax: ObjName.functionName(); //Constructors are special Funtions of Class that are responsible for initializing fields in the class. //Metadata is data about a data //Symbols are constants/objects which can be used to show metadata of a library/class IMPORTANT TOPICS: - //Dart Constructors Syntax: ClassName(ParamList){ //construtor body
//Other Object is used to put the value of Parameter in the Constructor. E.G. void main(){ //Object to put value in the parameter. Car myCar = new Car("Enn"); } //Other class class Car{ //Constructor Car(String engine){ print(engine); //Constructor body. } } ================================================== //Empty Constructors can also be created without Parameters & Objects are also created to call those constructors without the Value for Parameter. void main(){ //Object for calling that constructorl Car myCar = new Car(); } class Car{ //Empty Constructor Car(){ print("This is an empty constructor, ENGINE); } } //Named Constructors used to enable class dfeine multiple Constructors. //You can have 1 UnNamed Constructor while Have many Named Constructor =================================================== Multiple Constructors: //LETS DEFINE MULTIPLE CONSTRUCTORS IN A CLASS
//class class Car{ String engine; Car(String engine){ this.engine = engine; print(engine); } } ==================================================== Getters and Setters: - Getters AND Setters: Initialize and Retrive Values of Class Fields which are Present in Constructors 1Default Getter and Setter is present, which can be Overridden by explicitly Defining a new Getter/Setter Getter: Get Keyword, No Parameter, Return a Value Setter: Set Keyword, One Parameter, Not Return Value Syntax: ReturnType get identifier{ } set identifier{ } //You have to create a getter to get var value/return var; //Datatype is used for getting //Gettter no parameter //Return a value //You have to create a setter to set this.variable = variable; //Void is used to setting //Setter 1 parameter //Set a value
void main(){ Student s1 = new Student(); print(s1.studName); print(s1.studAge); } class Student{ //Two variables or Data to get and set String name; int age; //Create a setter; void set studName(name){ this.name = name; } //Create a getter String get studName{ return name; } //Create a setter for int var void set studAge(age){ if(age <= 5){ print("Age should be greater than 5"); }else{ this.age = age; } } //Create getter to return age; int get studAge{ return age; } }
class Student{ //method 1 void test1(){ print("Test 1 will be held on Monday."); } //Method 2 void test2(){ print("Test 2 will be held on Wednesday"); } } ===================================== DART Collections: - Dart doesnt support ARRAYS, DART COLLECTIONS can be used to replicate data like Arrays. LIST------------------ void main(){ List myGoal = new List(); myGoal.add("Dart"); myGoal.add("Flutter"); myGoal.add("C lang"); myGoal.add("PHP"); /print the list like array print(myGoal); /iterating accross the list i.e writing againg and again for(String type in myGoal){ print(type); } Size or length print(myGoal.length); yGoal.remove("PHP"); print("The updated list"); print(myGoal);
//Syntax to print List/set in forms of Each Object in new Line for(Datatype objName in ListName){ print(objName); } SET -------------------------------- Set represents a collection of Object in which each Object can occur only once. Sytax: Identifier = new Set(); Identifier = new Set.from(Iterable); Iterables are a list of values to add to a set. //Vertical print of set for(var obj in Identifier){ print(obj); } ===================================== Advanced Dart Collections: - HashMap HashSet LinkedList Queue HashMap: HashMap is hash Table based on implementation of Maps, which does not have a particular order
- datatype Identifier = new HashMap(); import 'dart:collection'; main() { var accounts = new HashMap(); accounts['dept']='HR'; accounts['name']='Tom';
print("Default implementation :${numberSet.runtimeType}"); for(var no in numberSet){ print(no); } } ========================================== Map: - var Identifier = new Map(); Identifier[‘key’] = ‘value’; ========================================== Queue: A queue is a collection that can be manupulated at both ends. It can add a element at start as well as end Queue Identifier = new Queue(); Identifier.add[]=’’; Identifier .addAll(); Identifier.addFirst(); Identifier .addLast(); ========================================== ITERATOR COLLECTIONSD: Iterator class enable easy collection traversal Each collection has an Iterator Property This property return a Iterator that points to a Object in the Collection Syntax : Iterator obj = IdentifierName.iterator; Current property of iterator shows where iterator is pointing currentl IteratorObj.current ========================================== GENERICS: - Dart Collections are Heterogenous, which can hold values of Various types,
Dart Collections can be made Homogenous using type-safety implementations Syntax: CollectionName identifier = new CollectionName(); ========================================== PACKAGES: - package manager for dart is pub Each dart application has a pubspec.yaml file which contains dependencies to other libraries and metadata of application like name, version,author, description ========================================== EXCEPTIONS: - each exceptions is a subtype of Exception Class there are try/on/catch blocks try Block: Embeds the code that might possibly result in a exceptions on Block: Used when exception type needs to be specified catch Block: used when the hander needs the Exception Object finally Block: Finally Block includes code that should be executed irrespecitve of an exception’s occurrence. The optional finally block executes unconditionally after try/on/catch block try { // code that might throw an exception } on Exception1 { // code for handling exception } catch Exception2 { // code for handling exception } many on/catch blocks can be created to handle multiple exceptions. try { // code that might throw an exception }
//VariableName(parameter) oper(23,345); oper = Sub; oper(4,4); oper = Div; oper(34,34); oper=Mul; oper(54, 98); } //Defing a typedef typedef manyOperations(int fn, int sn); Add(int fn, int sn){ print("ADD: ${fn + sn}"); } Sub(int fn, int sn){ print("SUB: ${fn - sn}"); } Div(int fn, int sn){ print("DIV: ${fn/sn}"); } Mul(int fn, int sn){ print("Mul: ${fn/sn}"); } Calculator(int fn, int sn, manyOperation oper){ print("Inside calculator"); oper(24,34); } //Passing typedef as parameter to a function void main(){
//Passing typedef as a parameter to a function Calculator(23, 43, Add); Calculator(43, 98, Sub); Calculator(98,21,Div); Calculator(76,45,Mul); } //Defing a typedef typedef manyOperations(int fn, int sn); Add(int fn, int sn){ print("ADD: ${fn + sn}"); } Sub(int fn, int sn){ print("SUB: ${fn - sn}"); } Div(int fn, int sn){ print("DIV: ${fn/sn}"); } Mul(int fn, int sn){ print("Mul: ${fn/sn}"); } Calculator(int fn, int sn, manyOperation oper){ print("Inside calculator"); oper(24,34); } ========================================== Concurrency: - Help in doing many parallel processes at same time. Dart:isolate package ==========================================
void main(){ //Stdout //Stdin stdout.write("Enter your name: "); var name = stdin.readLineSync(); print("Hi, $name!"); }
- Celsius to Fahrenheit Converter import 'dart:io'; void main() { print("Enter the temperature in Celsius: "); double C = double.parse(stdin.readLineSync()); double F = ((9/5)*C)-32; print(F); } ==========================================
