Tutorial by Examples: p

using System.Linq.Expressions; // Manually build the expression tree for // the lambda expression num => num < 5. ParameterExpression numParam = Expression.Parameter(typeof(int), "num"); ConstantExpression five = Expression.Constant(5, typeof(int)); BinaryExpression numLessTh...

// Define an expression tree, taking an integer, returning a bool. Expression<Func<int, bool>> expr = num => num < 5; // Call the Compile method on the expression tree to return a delegate that can be called. Func<int, bool> result = expr.Compile(); // Invoke the dele...

using System.Linq.Expressions; // Create an expression tree. Expression<Func<int, bool>> exprTree = num => num < 5; // Decompose the expression tree. ParameterExpression param = (ParameterExpression)exprTree.Parameters[0]; BinaryExpression operation = (BinaryExpression)exp...

This code will subscribe to the emails observable twice: emails.Where(email => email.From == "John").Subscribe(email => Console.WriteLine("A")); emails.Where(email => email.From == "Mary").Subscribe(email => Console.WriteLine("B")); To share a...

This code contains an overloaded method named Hello: class Example { public static void Hello(int arg) { Console.WriteLine("int"); } public static void Hello(double arg) { Console.WriteLine("double"); } public static vo...

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...

The following examples will not compile: string s = "\c"; char c = '\c'; Instead, they will produce the error Unrecognized escape sequence at compile time.

There are several places where you can use String.Format indirectly: The secret is to look for the overload with the signature string format, params object[] args, e.g.: Console.WriteLine(String.Format("{0} - {1}", name, value)); Can be replaced with shorter version: Console.WriteLine...

The nameof operator allows you to get the name of a variable, type or member in string form without hard-coding it as a literal. The operation is evaluated at compile-time, which means that you can rename, using an IDE's rename feature, a referenced identifier and the name string will update with it...

Snippet public void DoSomething(int paramValue) { Console.WriteLine(nameof(paramValue)); } ... int myValue = 10; DoSomething(myValue); Console Output paramValue

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) ...

Snippet public class SomeClass<TItem> { public void PrintTypeName() { Console.WriteLine(nameof(TItem)); } } ... var myClass = new SomeClass<int>(); myClass.PrintTypeName(); Console.WriteLine(nameof(SomeClass<int>)); Console Output TItem S...

Snippet Console.WriteLine(nameof(CompanyNamespace.MyNamespace)); Console.WriteLine(nameof(MyClass)); Console.WriteLine(nameof(MyClass.MyNestedClass)); Console.WriteLine(nameof(MyNamespace.MyClass.MyNestedClass.MyStaticProperty)); Console Output MyNamespace MyClass MyNestedClass MyStatic...

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

public string Foobar { get { return _foobar; } set { _foobar = value; } } private string _foobar = "xyz";

class Example { public string Foobar { get; set; } public List<string> Names { get; set; } public Example() { Foobar = "xyz"; Names = new List<string>(){"carrot","fox","ball"}; } }

Create a new file in your text editor or IDE named HelloWorld.java. Then paste this code block into the file and save: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } } Run live on Ideone Note: For Java to r...

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(); } ...