Programming Articles - Page 1184 of 3366

Dart provides us with a standard library named 'io' which contains different classes and in turn, these classes contains different methods that we can use to read or write input from the terminal.We import the library in our program by making use of the import command.ExampleConsider the example shown below −Import 'dart:io';Writing something to the terminalWe can write something to the terminal by making use of the standard out class (stdout) that is available to us in the 'dart:io' library.ExampleConsider the example shown below − Live Demoimport 'dart:io'; void main(List arguments) {    stdout.write('What is your name?\r'); }OutputWhat is your ... Read More

A queue is a collection of objects. In Dart, we can do operations on both ends of the queue.A queue can be created by making use of the Queue class this present inside the collection library of dart.ExampleConsider the example shown below − Live Demoimport 'dart:collection'; void main() {    var queue = new Queue();    print(queue); }In the above example, we imported the collection library so that Queue class can be used from it and then we create a Queue and store it in a variable named queue, and finally we print whatever is inside the queue variable.Output{}We can add ... Read More

Optional parameters are those parameters that don't need to be specified when calling the function. Optional parameters allow us to pass default values to parameters that we define. There are two types of optional parameters, mainly −Ordered (positional) optional parametersNamed optional parametersOrdered Optional ParametersOrdered optional parameters are those parameters that are wrapped in [ ]. For example, void printSomething(int a, int b, [ int c = 10] ){    // function body }They give us the freedom to call the function with or without the third parameter.ExampleConsider the example shown below − Live Demovoid printSomething(int a, int b, [ int c ... Read More

Dart has different null aware operators that we can use to make sure that we are not accessing the null values and to deal with them in a subtle way.Mainly, these are −?? operator??= operator? operatorWe will go through each of them in the following article.?? operatorThe ?? operator returns the first expression if and only if it is not null.ExampleConsider the example shown below −void main() {    var age;    age = age ?? 23;    print(age);    var name = "mukul";    name = name ?? "suruchi";    print(name); }In the above example, we declared two ... Read More

Multilevel inheritance in dart is the case when different classes are inheriting in a form of chain, i.e., one class extends some parent class, and the other class extends the class that was extending the parent class.The syntactical representation of multilevel inheritance looks something like this −class A {} class B extends A {} class C extends B {}If we notice the above syntax, we can clearly see that the class A is the parent class for the class B, which is extending it. Also, the class B acts as a parent for class C, which is extending class B.Multilevel ... Read More

Mixins in Dart are a way of using the code of a class again in multiple class hierarchies. We make use of the with keyword followed by one or more mixins names.Mixins can be used in two ways, the first case is when we want to make use of class code in such a way that the class doesn't have any constructor and the object of the class is extended. In such a case, we use the with keyword.Another case is when we want our mixin to be usable as a regular class, then we make use of the mixin keyword ... Read More

A method is a combination of statements which is used to attach some behavior to the class objects. It is used to perform some action on class objects, and we name methods so that we can recall them later in the program.Methods help in making the core more modular and in increasing the re-usability of the program.Information can be passed to methods through the parameters and then it can perform some operation on that information or it can even return values.Methods in a class are of two types, these are −Instance methodsClass methodsInstance MethodsInstance methods are methods that are present ... Read More

We know that we can access the methods that are present in the superclass from a subclass by making use of the super keyword or by simply creating objects of the subclass. Though, there may be different occasions when we want the subclass object to do things differently to the same method when invoked using subclass objects. We can achieve this by defining the same method again in the subclass with the same name, same arguments and same return type as in the same method that is present inside the superclass.Now, when we invoke that method, the method present in ... Read More

Maps are very important data structures as they allow us to map keys to some specific values, and later we can get the values from the keys.In Dart, we have different types of maps available to us. These mainly are −HashMapLinkedHashMapSplayTreeMapIn most cases, we make use of LinkedHashMap as it is very easy to create and make use of.Let's create a simple map in dart.ExampleConsider the example shown below − Live Demovoid main() {    var colors = new Map();    print(colors); }In the above example, we created an empty map and then printed it out. It should be noted that ... Read More

For loop is a type of definite loop in nature. There are mainly two types of loops that Dart provides us. Mainly these are −For loopFor-in loopWe will explore both of these loops in the below post.For loopFor loop in Dart follows a standard structure of the for loop that is present in C++ or Java. The structure of for loop in Dart looks something like this −Syntaxfor (initialization; condition; step) {    // Statements }ExampleConsider the example shown below - Live Demovoid main() {    for (int i = 0; i < 5; i++) {       print('TutorialsPoint : ... Read More