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If you are working with vectors or lines you will at some stage want to get the direction of a vector, or line. Or the direction from a point to another point. Math.atan(yComponent, xComponent) return the angle in radius within the range of -Math.PI to Math.PI (-180 to 180 deg) Direction of a vect...

If you have a vector in polar form (direction & distance) you will want to convert it to a cartesian vector with a x and y component. For referance the screen coordinate system has directions as 0 deg points from left to right, 90 (PI/2) point down the screen, and so on in a clock wise direction...

Math.sin and Math.cos are cyclic with a period of 2*PI radians (360 deg) they output a wave with an amplitude of 2 in the range -1 to 1. Graph of sine and cosine function: (courtesy Wikipedia) They are both very handy for many types of periodic calculations, from creating sound waves, to animati...

In XAML: <RadioButton IsChecked="{Binding EntityValue, Mode=TwoWay, Converter={StaticResource StringToIsCheckedConverter}, ConverterParameter=Male}" Content="Male"/> <RadioButton IsChecked="{Bindi...

public Result sayHello() { JsonNode json = request().body().asJson(); if(json == null) { return badRequest("Expecting Json data"); } else { String name = json.findPath("name").textValue(); if(name == null) { return badRequest...

@BodyParser.Of(BodyParser.Json.class) public Result sayHello() { JsonNode json = request().body().asJson(); String name = json.findPath("name").textValue(); if(name == null) { return badRequest("Missing parameter [name]"); } else { return ok...

A string can be used as a separator to join a list of strings together into a single string using the join() method. For example you can create a string where each element in a list is separated by a space. >>> " ".join(["once","upon","a","tim...

Python's string module provides constants for string related operations. To use them, import the string module: >>> import string string.ascii_letters: Concatenation of ascii_lowercase and ascii_uppercase: >>> string.ascii_letters 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQ...

CommandDescriptionzRedraw current line at the top of the window and put the cursor on the first non-blank character on the line.ztLike z but leave the cursor in the same column.z.Redraw current line at the center of the window and put the cursor on the first non-blank character on the line.zzLike z....

Sometimes we want to design our own UI for "Sign In With Facebook" button instead of the original button that comes with FacebookSDK. In your storyboard, drag your UIButton and set it however you want it to be. Ctrl + drag your button to your view controller as IBAction. Inside the IB...

Whenever AFNetworking is used the call is dispatched on a custom thread provided by AFNetworking. When the call returns to the completion block, it gets executed on the main thread. This example sets a custom thread that dispatch to the completion block: AFNetworking 2.xx: // Create dispatch_queu...

There are many cases when one has created an NSDate from only an hour and minute format, i.e: 08:12 that returns from a server as a String and you initiate an NSDate instance by these values only. The downside for this situation is that your NSDate is almost completely "naked" and what yo...

One can clear the user data of a specific app using adb: adb shell pm clear <package> This is the same as to browse the settings on the phone, select the app and press on the clear data button. pm invokes the package manager on the device clear deletes all data associated with a packag...

Gradle has the ability to add a wrapper to projects. This wrapper alleviates the need for all users or continuous integration systems to have Gradle installed. It also prevents version issues where there is some incompatibility between the version the project uses and that which users have installed...

RoboGuice is a framework that brings the simplicity and ease of Dependency Injection to Android, using Google's own Guice library. RoboGuice 3 slims down your application code. Less code means fewer opportunities for bugs. It also makes your code easier to follow -- no longer is your code littered ...

It's possible to break / continue to an outer loop by using label statements: outerloop: for(...) { innerloop: for(...) { if(condition1) break outerloop; if(condition2) continue innerloop; // equivalent to: continue; } } There is no ...

The continue statement is used to skip the remaining steps in the current iteration and start with the next loop iteration. The control goes from the continue statement to the step value (increment or decrement), if any. String[] programmers = {"Adrian", "Paul", "John&quot...

By default class annotations do not apply to types extending them. This can be changed by adding the @Inherited annotation to the annotation definition Example Consider the following 2 Annotations: @Inherited @Target(ElementType.TYPE) @Retention(RetentionPolicy.RUNTIME) public @interface Inher...

User is an ActiveRecord or Mongoid class. Replace User with any Rails class in your project (even something like Integer or Array) my_string = "User" # Capitalized string # => 'User' my_constant = my_string.safe_constantize # => User my_constant.all.count # => 18 my...

This example will not work because the string passed in isn't recognized as a constant in the project. Even if you pass in "array", it won't work as it isn't capitalized. my_string = "not_a_constant" # => 'not_a_constant' my_string.safe_constantize # => nil my_s...