Tutorial by Examples: b

Specifying the -gui command line option when running an ANTLR grammar in the test rig will result in a window popping up with a visual representation of the parse tree. For example: Given the following grammar: JSON.g4 /** Taken from "The Definitive ANTLR 4 Reference" by Terence Parr */...

#demo-element { background: @theme-color; color: contrast(@theme-color, black, white, 50%); } @theme-color: red; The above example will set the text color of the element as white if the background-color is dark and vice-versa. This is achieved using the contrast() color operation functi...

PresenceOf - Validates that a value is not null or empty string $validator->add('name', new \Phalcon\Validation\Validator\PresenceOf([ 'message' => 'The name is required' ])); Email - Checks if a value has a correct e-mail format $validator->add('email', new \Phalcon\Validation\Va...

6.0 Default SET format is MMDDhhmm[[CC]YY][.ss], that's (2 digits each) For example, to set July 17'th 10:10am, without changing the current year, type: adb shell 'date 07171010.00' Tip 1: the date change will not be reflected immediately, and a noticable change will happen only after the syst...

Put your dbname.sqlite or dbname.db file in assets folder of your project. public class Databasehelper extends SQLiteOpenHelper { public static final String TAG = Databasehelper.class.getSimpleName(); public static int flag; // Exact Name of you db file that you put in as...

Having more than one element with the same ID is a hard to troubleshoot problem. The HTML parser will usually try to render the page in any case. Usually no error occurs. But the pace could end up in a mis-behaving web page. In this example: <div id="aDiv">a</div> <div id...

A spring bean can be configured such that it will register only if it has a particular value or a specified property is met. To do so, implement Condition.matches to check the property/value: public class PropertyCondition implements Condition { @Override public boolean matches(ConditionC...

By default: Use val, not var, wherever possible. This allows you to take seamless advantage of a number of functional utilities, including work distribution. Use recursion and comprehensionss, not loops. Use immutable collections. This is a corrolary to using val whenever possible. Focus on da...

This example shows a white Snackbar with custom Undo icon. Snackbar customBar = Snackbar.make(view , "Text to be displayed", Snackbar.LENGTH_LONG); customBar.setAction("UNDO", new View.OnClickListener() { @Override public void onClick(View view) { //Put the logic...

Say we have Products and Categorys in a many-to-many relationship: public class Product { public Product() { Categories = new HashSet<Category>(); } public int ProductId { get; set; } public string ProductName { get; set; } public virtual ICollection&lt...

There is no format specifier to print boolean type using NSLog. One way to print boolean value is to convert it to a string. BOOL boolValue = YES; NSLog(@"Bool value %@", boolValue ? @"YES" : @"NO"); Output: 2016-07-30 22:53:18.269 Test[4445:64129] Bool value YES ...

The Fibonacci numbers are defined inductively as F0 = 0 F1 = 1 Fn+2 = Fn + Fn+1 The sum of the first n+1 Fibonacci numbers is given by F0 + F1 + F2 + ... + Fn = Fn+2 - 1. This summation arises, among other places, in the analysis of Fibonacci heaps, where it's used to provide a lower b...

You can animate complex changes to your collection view using the performBatchUpdates method. Inside the update block, you can specify several modifications to have them animate all at once. collecitonView.performBatchUpdates({ // Perform updates }, nil) Inside the update block, you can pe...

Pressing C-h a will run the emacs function apropos-command which makes emacs prompt for words (or a regexp) to search for. It will then show a buffer containing a list of names and descriptions related to that topic, including key bindings for each of the functions available via keystrokes. Pressin...

C-h k runs the function describe-key, which looks up the function mapped to the key strokes provided, and presents a description of the function which will be run when these keys are pressed. C-h c runs the function describe-key-briefly, which only displays the function name mapped to given key seq...

Another powerful & mature concurrency tool in Haskell is Software Transactional Memory, which allows for multiple threads to write to a single variable of type TVar a in an atomic manner. TVar a is the main type associated with the STM monad and stands for transactional variable. They're used m...

A Haskell project can either use the system wide packages or use a sandbox. A sandbox is an isolated package database and can prevent dependency conflicts, e. g. if multiple Haskell projects use different versions of a package. To initialize a sandbox for a Haskell package go to its directory and r...

After you have opened a split window in vim (as demonstrated by many examples under this tag) then you will likely want to control windows quickly. Here is how to control split windows using keyboard shortcuts. Move to split Above/Below: Ctrl + w and k Ctrl + w and j Move to split Left/Right...

The Window Object contains the following properties. PropertyDescriptionwindow.closedWhether the window has been closedwindow.lengthNumber of <iframe> elements in windowwindow.nameGets or sets the name of the windowwindow.innerHeightHeight of windowwindow.innerWidthWidth of windowwindow.scree...

Many unbound generic parameters, like those used in a static method, cannot be recovered at runtime (see Other Threads on Erasure). However there is a common strategy employed for accessing the type satisfying a generic parameter on a class at runtime. This allows for generic code that depends on ac...