Tutorial by Examples: c

Consider we have a class Animal which has a child class Dog class Animal { public Animal() { Console.WriteLine("In Animal's constructor"); } } class Dog : Animal { public Dog() { Console.WriteLine("In Dog's constructor"); } ...

First of all, implement your view holder: implements View.OnClickListener, View.OnLongClickListener Then, register the listeners as follows: itemView.setOnClickListener(this); itemView.setOnLongClickListener(this); Next, override the listeners as follows: @Override public void onClick(Vie...

Properties are members of an object. Each named property is a pair of (name, descriptor). The name is a string that allows access (using the dot notation object.propertyName or the square brackets notation object['propertyName']). The descriptor is a record of fields defining the bevahiour of the pr...

select LastName, FirstName, from Person Returns message: Error Code: 1064. You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'from Person' at line 2. Getting a "1064 error" message from MySQL mean...

By default error message appears below textbox in <div class="help-block"></div> on keyUp or after pressing submit button if any validation constraints aren't met. Sometimes we want a message on submit only i.e. no validation at onKeyup event. Let's check yii2/widgets/ActiveF...

// decode NSString *string = [[NSString alloc] initWithData:utf8Data encoding:NSUTF8StringEncoding]; // encode NSData *utf8Data = [string dataUsingEncoding:NSUTF8StringEncoding]; Some supported encodings are: NSASCIIStringEncoding NSUTF8StringEnc...

A Kotlin interface contains declarations of abstract methods, and default method implementations although they cannot store state. interface MyInterface { fun bar() } This interface can now be implemented by a class as follows: class Child : MyInterface { override fun bar() { ...

An interface in Kotlin can have default implementations for functions: interface MyInterface { fun withImplementation() { print("withImplementation() was called") } } Classes implementing such interfaces will be able to use those functions without reimplementing cl...

Different flavors of application builds can contain different resources. To create a flavor-specific resource make a directory with the lower-case name of your flavor in the src directory and add your resources in the same way you would normally. For example, if you had a flavour Development and w...

All java Collection<E>s have stream() and parallelStream() methods from which a Stream<E> can be constructed: Collection<String> stringList = new ArrayList<>(); Stream<String> stringStream = stringList.parallelStream(); A Stream<E> can be created from an arra...

Java 8 provides classes called IntSummaryStatistics, DoubleSummaryStatistics and LongSummaryStatistics which give a state object for collecting statistics such as count, min, max, sum, and average. Java SE 8 List<Integer> naturalNumbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); IntSu...

What is recursion: In general, recursion is when a function invokes itself, either directly or indirectly. For example: // This method calls itself "infinitely" public void useless() { useless(); // method calls itself (directly) } Conditions for applying recursion to a probl...

There are 5 different types (MKMapType), MKMapView can display. iPhone OS 3 .standard Displays a street map that shows the position of all roads and some road names. Swift 2 mapView.mapType = .Standard Swift 3 mapView.mapType = .standard Objective-C _mapView.mapType = MKMapTypeStandard;...

Elements of the same class can often be concatenated into arrays (with a few rare exceptions, e.g. function handles). Numeric scalars, by default of class double, can be stored in a matrix. >> A = [1, -2, 3.14, 4/5, 5^6; pi, inf, 7/0, nan, log(0)] A = 1.0e+04 * 0.0001 -0.0002 0...

The for and while compound statements (loops) can optionally have an else clause (in practice, this usage is fairly rare). The else clause only executes after a for loop terminates by iterating to completion, or after a while loop terminates by its conditional expression becoming false. for i in r...

In this example, we will look at a method for returning the last non-empty row in a column for a data set. This method will work regardless of empty regions within the data set. However caution should be used if merged cells are involved, as the End method will be "stopped" against a mer...

Another neat feature using slices is slice assignment. Python allows you to assign new slices to replace old slices of a list in a single operation. This means that if you have a list, you can replace multiple members in a single assignment: lst = [1, 2, 3] lst[1:3] = [4, 5] print(lst) # Out: [1...

Dart has a switch case which can be used instead of long if-else statements: var command = 'OPEN'; switch (command) { case 'CLOSED': executeClosed(); break; case 'OPEN': executeOpen(); break; case 'APPROVED': executeApproved(); break; case 'UNSURE': ...

To check for a precise number of elements in the collection def f(ints: Seq[Int]): String = ints match { case Seq() => "The Seq is empty !" case Seq(first) => s"The seq has exactly one element : $first" case Seq(first, second) => s"The...

All Java exceptions are instances of classes in the Exception class hierarchy. This can be represented as follows: java.lang.Throwable - This is the base class for all exception classes. Its methods and constructors implement a range of functionality common to all exceptions. java.lang.Excep...