Tutorial by Examples: d

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...

Typically, when using UIControl or UIButton, we add a selector as a callback action for when an event occurs on a button or control, such as the user pressing the button or touching the control. For example, we would do the following: import UIKit class ViewController: UIViewController { @...

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...

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...

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();...

Add the following dependency to your project level build.gradle file. dependencies { classpath "io.realm:realm-gradle-plugin:3.1.2" } Add the following right at the top of your app level build.gradle file. apply plugin: 'realm-android' Complete a gradle sync and you now have ...

Realm models must extend the RealmObject base class, they define the schema of the underlying database. Supported field types are boolean, byte, short, int, long, float, double, String, Date, byte[], links to other RealmObjects, and RealmList<T extends RealmModel>. public class Person extend...

In C, all function parameters are passed by value, so modifying what is passed in callee functions won't affect caller functions' local variables. #include <stdio.h> void modify(int v) { printf("modify 1: %d\n", v); /* 0 is printed */ v = 42; printf("modify 2:...

(defun fn (x) (cond (test-condition1 the-value1) (test-condition2 the-value2) ... ... ... (t (fn reduced-argument-x)))) CL-USER 2788 > (defun my-fib (n) (cond ((= n 1) 1) ((= n...

(defun fn (x) (cond (test-condition the-value) (t (fn reduced-argument-x))))

Ruby has an or-equals operator that allows a value to be assigned to a variable if and only if that variable evaluates to either nil or false. ||= # this is the operator that achieves this. this operator with the double pipes representing or and the equals sign representing assigning of a valu...

Given a string, strspn calculates the length of the initial substring (span) consisting solely of a specific list of characters. strcspn is similar, except it calculates the length of the initial substring consisting of any characters except those listed: /* Provided a string of "tokens&quo...

This method just returns the first argument. var res1 = _.identity(10, 20); // res1 now is 10 var res2 = _.identity("hello", "world"); // res2 now is "hello" What does _.identity mean in lodash documentation? This method is used throughout lodash documentation...

Calling the dependencies task allows you to see the dependencies of the root project: gradle dependencies The results are dependency graphs (taking into account transitive dependencies), broken down by configuration. To restrict the displayed configurations, you can pass the --configuration opti...

You have to point Gradle to the location of your plugins so Gradle can find them. Do this by adding a repositories { ... } to your build.gradle. Here's an example of adding three repositories, JCenter, Maven Repository, and a custom repository that offers dependencies in Maven style. repositories...

This example shows how to open a default dialer (an app that makes regular calls) with a provided telephone number already in place: Intent intent = new Intent(Intent.ACTION_DIAL); intent.setData(Uri.parse("tel:9988776655")); //Replace with valid phone number. Remember to add the tel: pr...

You can pass latitude, longitude from your app to Google map using Intent String uri = String.format(Locale.ENGLISH, "http://maps.google.com/maps?q=loc:%f,%f", 28.43242324,77.8977673); Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(uri)); startActivity(intent);

Rules for creating a dictionary: Every key must be unique (otherwise it will be overridden) Every key must be hashable (can use the hash function to hash it; otherwise TypeError will be thrown) There is no particular order for the keys. # Creating and populating it with values stock = {'egg...

def foobar(foo=None, bar=None): return "{}{}".format(foo, bar) values = {"foo": "foo", "bar": "bar"} foobar(**values) # "foobar"

class A: x = None # type: float def __init__(self, x: float) -> None: """ self should not be annotated init should be annotated to return None """ self.x = x @classmethod def from_int(cls, x: int...