Tutorial by Examples: class

public class IntStack { private IntStackNode head; // IntStackNode is the inner class of the class IntStack // Each instance of this inner class functions as one link in the // Overall stack that it helps to represent private static class IntStackNode { privat...

When creating a nested class, you face a choice of having that nested class static: public class OuterClass1 { private static class StaticNestedClass { } } Or non-static: public class OuterClass2 { private class NestedClass { } } At its core, static nested c...

A full explanation of Access Modifiers in Java can be found here. But how do they interact with Inner classes? public, as usual, gives unrestricted access to any scope able to access the type. public class OuterClass { public class InnerClass { public int x = 5; } p...

Protocol oriented programing can be used as a core Swift design pattern. Different types are able to conform to the same protocol, value types can even conform to multiple protocols and even provide default method implementation. Initially protocols are defined that can represent commonly used pro...

Often you will want to wrap some of Android's classes in easier to use utility classes. Those utility classes often require a context to access the android OS or your apps' resources. A common example of this is a wrapper for the SharedPreferences class. In order to access Androids shared preference...

The symbol NA is for a logical missing value: class(NA) #[1] "logical" This is convenient, since it can easily be coerced to other atomic vector types, and is therefore usually the only NA you will need: x <- c(1, NA, 1) class(x[2]) #[1] "numeric" If you do need a s...

With the Class Based generic Views, it is very simple and easy to create the CRUD views from our models. Often, the built in Django admin is not enough or not preferred and we need to roll our own CRUD views. The CBVs can be very handy in such cases. The CreateView class needs 3 things - a model, t...

Let's say, we have a simple LoginForm class with rules() method (used in login page as framework template): class LoginForm { public $email; public $rememberMe; public $password; /* rules() method returns an array with what each field has as a requirement. * Login form u...

To customize appearance of all instances of a class, access appearance proxy of the desired class. For example: Set UIButton tint color Swift: UIButton.appearance().tintColor = UIColor.greenColor() Objective-C: [UIButton appearance].tintColor = [UIColor greenColor]; Set UIButton background...

Use appearanceWhenContainedInInstancesOfClasses: to customize the appearance for instance of a class when contained within an instance of container class. For example customization of UILabel's textColor and backgroundColor within ViewController class will look like this: Set UILabel text color Sw...

Functionality in metaclasses can be changed so that whenever a class is built, a string is printed to standard output, or an exception is thrown. This metaclass will print the name of the class being built. class VerboseMetaclass(type): def __new__(cls, class_name, class_parents, class_dict)...

A class or struct can also contain another class/struct definition inside itself, which is called a "nested class"; in this situation, the containing class is referred to as the "enclosing class". The nested class definition is considered to be a member of the enclosing class, b...

Place next java class in src/androidTest/java and run it. public class UITest { @Test public void Simple_Test() { onView(withId(R.id.my_view)) // withId(R.id.my_view) is a ViewMatcher .perform(click()) // click() is a ViewAction .check(matches(isDi...

The following is a simple example of using the strategy pattern without a context class. There are two implementation strategies which implement the interface and solve the same problem in different ways. Users of the EnglishTranslation class can call the translate method and choose which strategy t...

Classes provide a way of creating your own types within the .NET framework. Within a class definition you may include the following: Fields Properties Methods Constructors Events To declare a class you use the following syntax: Public Class Vehicle End Class Other .NET types can...

If classes share common functionality you can group this in a base or abstract class. Abstract classes can contain partial or no implementation at all and allow the derived type to override the base implementation. Abstract classes within VisualBasic.NET must be declared as MustInherit and cannot ...

You can use Help class in code, to provide these kinds of help: Show a help pop-up for a control Open a CHM file based on context (Show table of content, Show a keyword or index, show a topic) Navigate to a URL using default browser Show Help pop-up window You can use Help.ShowPopup to disp...

The following examples will use this class hierarchy: struct A { int m; }; struct B : A {}; struct C : B {}; The conversion from derived class type to base class type is preferred to user-defined conversions. This applies when passing by value or by reference, as well as when converting pointe...

Although available, defining a class from scratch is not recommended in modern Perl. Use one of helper OO systems which provide more features and convenience. Among these systems are: Moose - inspired by Perl 6 OO design Class::Accessor - a lightweight alternative to Moose Class::Tiny...

Every object in R is assigned a class. You can use class() to find the object's class and str() to see its structure, including the classes it contains. For example: class(iris) [1] "data.frame" str(iris) 'data.frame': 150 obs. of 5 variables: $ Sepal.Length: num 5.1 4.9 4.7 4...