Tutorial by Examples: f

Using Iterable in for loop

Classes implementing Iterable<> interface can be used in for loops. This is actually only syntactic sugar for getting an iterator from the object and using it to get all elements sequentially; it makes code clearer, faster to write end less error-prone. public class UsingIterable { pub...

Java Language • Iterator and Iterable

Automatic field/property XML mapping configuration (@XmlAccessorType)

Annotation @XmlAccessorType determines whether fields/properties will be automatically serialized to XML. Note, that field and method annotations @XmlElement, @XmlAttribute or @XmlTransient take precedence over the default settings. public class XmlAccessTypeExample { @XmlAccessorType(XmlAccessT...

Java Language • JAXB

Manual field/property XML mapping configuration

Annotations @XmlElement, @XmlAttribute or @XmlTransient and other in package javax.xml.bind.annotation allow the programmer to specify which and how marked fields or properties should be serialized. @XmlAccessorType(XmlAccessType.NONE) // we want no automatic field/property marshalling public cla...

Java Language • JAXB

Get the page history of a WebView

WebHistory history = webView.getEngine().getHistory(); The history is basically a list of entries. Each entry represents a visited page and it provides access to relevant page info, such as URL, title, and the date the page was last visited. The list can be obtained by using the getEntries() met...

javafx • WebView and WebEngine

Flow layout

import javax.swing.*; import java.awt.FlowLayout; public class FlowExample { public static void main(String[] args){ SwingUtilities.invokeLater(new Runnable(){ @Override public void run(){ JPanel panel = new JPanel(); pa...

swing • Layout management

Avoiding NullReferenceExceptions

var person = new Person { Address = null; }; var city = person.Address.City; //throws a NullReferenceException var nullableCity = person.Address?.City; //returns the value of null This effect can be chained together: var person = new Person { Address = new Address { ...

C# Language • Null-conditional Operators

Minor changes and bugfixes

Parentheses are now forbidden around named parameters. The following compiles in C#5, but not C#6 5.0 Console.WriteLine((value: 23)); Operands of is and as are no longer allowed to be method groups. The following compiles in C#5, but not C#6 5.0 var result = "".Any is byte; T...

C# Language • C# 6.0 Features

Usefulness of interfaces

Interfaces can be extremely helpful in many cases. For example, say you had a list of animals and you wanted to loop through the list, each printing the sound they make. {cat, dog, bird} One way to do this would be to use interfaces. This would allow for the same method to be called on all of th...

Java Language • Interfaces

Run code only if there is a value present

Optional<String> optionalWithValue = Optional.of("foo"); optionalWithValue.ifPresent(System.out::println);//Prints "foo". Optional<String> emptyOptional = Optional.empty(); emptyOptional.ifPresent(System.out::println);//Does nothing.

Java Language • Optional

Functions as a variable

A normal function declaration looks like this: function foo(){ } A function defined like this is accessible from anywhere within its context by its name. But sometimes it can be useful to treat function references like object references. For example, you can assign an object to a variable based...

JavaScript • Functions

HTML output from web server

PHP can be used to add content to HTML files. While HTML is processed directly by a web browser, PHP scripts are executed by a web server and the resulting HTML is sent to the browser. The following HTML markup contains a PHP statement that will add Hello World! to the output: <!DOCTYPE html&gt...

PHP • Getting started with PHP

Standard function prototype

Start by defining a Foo function that we'll use as a constructor. function Foo (){} By editing Foo.prototype, we can define properties and methods that will be shared by all instances of Foo. Foo.prototype.bar = function() { return 'I am bar'; }; We can then create an instance using the ...

JavaScript • Inheritance

Anonymous Function

Defining an Anonymous Function When a function is defined, you often give it a name and then invoke it using that name, like so: foo(); function foo(){ // ... } When you define a function this way, the Javascript runtime stores your function in memory and then creates a reference to th...

JavaScript • Functions

Difference between Object.key and Object.prototype.key

Unlike in languages like Python, static properties of the constructor function are not inherited to instances. Instances only inherit from their prototype, which inherits from the parent type's prototype. Static properties are never inherited. function Foo() {}; Foo.style = 'bold'; var foo = ne...

JavaScript • Inheritance

Basic use of map, itertools.imap and future_builtins.map

The map function is the simplest one among Python built-ins used for functional programming. map() applies a specified function to each element in an iterable: names = ['Fred', 'Wilma', 'Barney'] Python 3.x3.0 map(len, names) # map in Python 3.x is a class; its instances are iterable # Out: &...

Python Language • Map Function

Basic use of filter

To filter discards elements of a sequence based on some criteria: names = ['Fred', 'Wilma', 'Barney'] def long_name(name): return len(name) > 5 Python 2.x2.0 filter(long_name, names) # Out: ['Barney'] [name for name in names if len(name) > 5] # equivalent list comprehension #...

Python Language • Filter

Your first Swift program

Write your code in a file named hello.swift: print("Hello, world!") To compile and run a script in one step, use swift from the terminal (in a directory where this file is located): To launch a terminal, press CTRL+ALT+T on Linux, or find it in Launchpad on macOS. To change dire...

Swift Language • Getting started with Swift Language

Non-HTML output from web server

In some cases, when working with a web server, overriding the web server's default content type may be required. There may be cases where you need to send data as plain text, JSON, or XML, for example. The header() function can send a raw HTTP header. You can add the Content-Type header to notify t...

PHP • Getting started with PHP

Outputting a structured view of arrays and objects

print_r() - Outputting Arrays and Objects for debugging print_r will output a human readable format of an array or object. You may have a variable that is an array or object. Trying to output it with an echo will throw the error: Notice: Array to string conversion. You can instead use the print_r...

PHP • Outputting the Value of a Variable

Accessing values of a dictionary

dictionary = {"Hello": 1234, "World": 5678} print(dictionary["Hello"]) The above code will print 1234. The string "Hello" in this example is called a key. It is used to lookup a value in the dict by placing the key in square brackets. The number 1234 is ...

Python Language • Dictionary