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Event declaration: public event EventHandler<EventArgsT> EventName; Event handler declaration: public void HandlerName(object sender, EventArgsT args) { /* Handler logic */ } Subscribing to the event: Dynamically: EventName += HandlerName; Through the Designer: Click the Events...

Event declaration: public event EventHandler<EventArgsType> EventName; Event handler declaration using lambda operator => and subscribing to the event: EventName += (obj, eventArgs) => { /* Handler logic */ }; Event handler declaration using delegate anonymous method syntax: Eve...

Events can be of any delegate type, not just EventHandler and EventHandler<T>. For example: //Declaring an event public event Action<Param1Type, Param2Type, ...> EventName; This is used similarly to standard EventHandler events: //Adding a named event handler public void HandlerNa...

Given an async method like this: Task<string> GetNameAsync(CancellationToken cancellationToken) Wrap it as an IObservable<string> like this: Observable.FromAsync(cancellationToken => GetNameAsync(cancellationToken))

using System; using System.Reflection; using System.Reflection.Emit; class DemoAssemblyBuilder { public static void Main() { // An assembly consists of one or more modules, each of which // contains zero or more types. This code creates a single-module // a...

var sequenceOfSequences = new [] { new [] { 1, 2, 3 }, new [] { 4, 5 }, new [] { 6 } }; var sequence = sequenceOfSequences.SelectMany(x => x); // returns { 1, 2, 3, 4, 5, 6 } Use SelectMany() if you have, or you are creating a sequence of sequences, but you want the result as one long sequen...

The SelectMany linq method 'flattens' an IEnumerable<IEnumerable<T>> into an IEnumerable<T>. All of the T elements within the IEnumerable instances contained in the source IEnumerable will be combined into a single IEnumerable. var words = new [] { "a,b,c", "d,e&quo...

The following program: class Program { static void Method(params Object[] objects) { System.Console.WriteLine(objects.Length); } static void Method(Object a, Object b) { System.Console.WriteLine("two"); } static void Main(string[] a...

Snippet public class Person : INotifyPropertyChanged { private string _address; public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged(string propertyName) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName))...

Snippet public class BugReport : INotifyPropertyChanged { public string Title { ... } public BugStatus Status { ... } } ... private void BugReport_PropertyChanged(object sender, PropertyChangedEventArgs e) { var bugReport = (BugReport)sender; switch (e.PropertyName) ...

Create a property with getter and/or setter and initialize all in one line: public string Foobar { get; set; } = "xyz";

Declaration of an interface using the interface keyword: public interface Animal { String getSound(); // Interface methods are public by default } Override Annotation @Override public String getSound() { // Code goes here... } This forces the compiler to check that we are overri...

An exception can be caught and handled using the try...catch statement. (In fact try statements take other forms, as described in other examples about try...catch...finally and try-with-resources.) Try-catch with one catch block The most simple form looks like this: try { doSomething(); } ...

We can create an ArrayList (following the List interface): List aListOfFruits = new ArrayList(); Java SE 5 List<String> aListOfFruits = new ArrayList<String>(); Java SE 7 List<String> aListOfFruits = new ArrayList<>(); Now, use the method add to add a String: ...

The following example shows the basics of throwing an exception: public void checkNumber(int number) throws IllegalArgumentException { if (number < 0) { throw new IllegalArgumentException("Number must be positive: " + number); } } The exception is thrown on the 3...

android:layout_gravity android:layout_gravity is used to set the position of an element in its parent (e.g. a child View inside a Layout). Supported by LinearLayout and FrameLayout android:gravity android:gravity is used to set the position of content inside an element (e.g. a text insid...

Basic cases int[] numbers1 = new int[3]; // Array for 3 int values, default value is 0 int[] numbers2 = { 1, 2, 3 }; // Array literal of 3 int values int[] numbers3 = new int[] { 1, 2, 3 }; // Array of 3 int values initialized int[][] numbers4 = { { 1, 2...

This example will start DestinationActivity from OriginActivity. Here, the Intent constructor takes two parameters: A Context as its first parameter (this is used because the Activity class is a subclass of Context) The Class of the app component to which the system should deliver the Intent (i...

An interface can extend another interface via the extends keyword. public interface BasicResourceService { Resource getResource(); } public interface ExtendedResourceService extends BasicResourceService { void updateResource(Resource resource); } Now a class implementing ExtendedR...

Addition Map<Integer, String> map = new HashMap<>(); map.put(1, "First element."); System.out.println(map.get(1)); Output: First element. Override Map<Integer, String> map = new HashMap<>(); map.put(1, "First element."); map.put(1, &quot...