Tutorial by Examples: l

Autoboxing can come at a substantial memory overhead. For example: Map<Integer, Integer> square = new HashMap<Integer, Integer>(); for(int i = 256; i < 1024; i++) { square.put(i, i * i); // Autoboxing of large integers } will typically consume substantial amount of memory (...

First you need to install and start your Redis server, check the link below that can help you to install redis on you server or local machine. Installation and Setup Now open your command prompt and run command redis-cli : To save first set >SET 'keyname' then 'value' 127.0.0.1:6379> SET h...

Swift //Swift let viewController = UIViewController() let navigationController = UINavigationController(rootViewController: viewController) //Objective-C UIViewController *viewController = [[UIViewController alloc] init]; UINavigationController *navigationController = [[UINavigationControlle...

//Swift let fooViewController = UIViewController() navigationController?.pushViewController(fooViewController, animated: true) //Objective-C UIViewController *fooViewController = [[UIViewController alloc] init]; [navigationController pushViewController:fooViewController animated:YES];

As we know that we should use synchronized keyword to make execution of a method or block exclusive. But few of us may not be aware of one more important aspect of using synchronized and volatile keyword: apart from making a unit of code atomic, it also provides read / write barrier. What is this re...

It is common within applications to need to have code like this : a = a + 1 or a = a * 2 There is an effective shortcut for these in place operations : a += 1 # and a *= 2 Any mathematic operator can be used before the '=' character to make an inplace operation : -= decrement the va...

YAML is a text based format allowing to store structured data in a hierarchy. YAML is designed to be human and machine readable with a minimum of overhead. The YAML specification can be found at yaml.org. There is also a reference card Comments start with # and go till newline, comments must be sep...

lazy val is a language feature where the initialization of a val is delayed until it is accessed for the first time. After that point, it acts just like a regular val. To use it add the lazy keyword before val. For example, using the REPL: scala> lazy val foo = { | println("Initial...

If you've got multiple implementations of the same interface, Spring can autowire them all into a collection object. I'm going to use an example using a Validator pattern1 Foo Class: public class Foo { private String name; private String emailAddress; private String errorMessage;...

All of the Bitwise operators (except ~) have their own in place versions a = 0b001 a &= 0b010 # a = 0b000 a = 0b001 a |= 0b010 # a = 0b011 a = 0b001 a <<= 2 # a = 0b100 a = 0b100 a >>= 2 # a = 0b001 a = 0b101 a ^= 0b011 # a = 0b110

Linux has a command for almost any tasks and most of them are intuitive and easily interpreted. Getting Help in Linux CommandUsabilityman <name>Read the manual page of <name>.man <section> <name>Read the manual page of <name>, related to the given section.man -k <e...

Linux uses some conventions for present and parent directories. This can be a little confusing for beginners. Whenever you are in a terminal in Linux, you will be in what is called the current working directory. Often your command prompt will display either the full working directory, or just the l...

private static void explicitTaskParallism() { Thread.CurrentThread.Name = "Main"; // Create a task and supply a user delegate by using a lambda expression. Task taskA = new Task(() => Console.WriteLine($"Hello from task {nameof(taskA)}.")...

private static void Main(string[] args) { var a = new A(); var b = new B(); //implicit task parallelism Parallel.Invoke( () => a.DoSomeWork(), () => b.DoSomeOtherWork() ); }

This example assumes that you have experience in creating Rails applications. To create an API-only app in Rails 5, run rails new name-of-app --api Add active_model_serializers in Gemfile gem 'active_model_serializers' install bundle in terminal bundle install Set the ActiveModelSeriali...

Installing Rails on Ubuntu On a clean ubuntu, installation of Rails should be straight forward Upgrading ubuntu packages sudo apt-get update sudo apt-get upgrade Install Ruby and Rails dependecies sudo apt-get install git-core curl zlib1g-dev build-essential libssl-dev libreadline-dev libyam...

Corner radius for all 4 edges: UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRoundedRect: CGRectMake(x,y,width,height) cornerRadius: 11]; [UIColor.grayColor setFill]; [rectanglePath fill]; Corner radius for top-left edge: UIBezierPath* rectanglePath = [UIBezierPath bezierPat...

For a simple circle: UIBezierPath* ovalPath = [UIBezierPath bezierPathWithOvalInRect: CGRectMake(0,0,50,50)]; [UIColor.grayColor setFill]; [ovalPath fill]; Swift: let ovalPath = UIBezierPath(ovalInRect: CGRect(x: 0, y: 0, width: 50, height: 50)) UIColor.grayColor().setFill() ovalPath.fill...

For bezier path to get resized based on the view frame, override the drawRect of view that you are drawing the bezier path : - (void)drawRect:(CGRect)frame { UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: CGRectMake(CGRectGetMinX(frame), CGRectGetMinY(frame), CGRectGetWidth(f...

Consider a simple rectangle that is drawn by the bezier path. UIBezierPath* rectanglePath = [UIBezierPath bezierPathWithRect: CGRectMake(x,y,width,height)]; [UIColor.grayColor setFill]; [rectanglePath fill]; Basic Outer-fill shadow: CGContextRef context = UIGraphicsGetCurrentContext();...