Prior to Java 5's concurrent package introduction threading was more low level.The introduction of this package provided several higher level concurrent programming aids/constructs.
Locks are thread synchronisation mechanisms that essentially serve the same purpose as synchronized blocks or key wor...
To make a jar, you need one or more class files. This should have a main method if it is to be run by a double click.
For this example, we will use:
import javax.swing.*;
import java.awt.Container;
public class HelloWorld {
public static void main(String[] args) {
JFrame f = ne...
#include <gtkmm/application.h>
#include <gtkmm/applicationwindow.h>
#include <gtkmm/button.h>
// main window of the application
class HelloWorldWindow : public Gtk::ApplicationWindow {
// a simple push button
Gtk::Button btn;
public:
HelloWorldWindow()
: ...
Starting with the Support Library version 22.2.1, it's possible to show and hide a FloatingActionButton from scrolling behavior using a FloatingActionButton.Behavior sublclass that takes advantage of the show() and hide() methods.
Note that this only works with a CoordinatorLayout in conjunction wi...
A floating point type. Has the narrowest range out of the three floating point types in C++.
float area(float radius) {
const float pi = 3.14159f;
return pi*radius*radius;
}
A floating point type. Its range includes that of float. When combined with long, denotes the long double floating point type, whose range includes that of double.
double area(double radius) {
const double pi = 3.141592653589793;
return pi*radius*radius;
}
Denotes a signed integer type that is at least as long as int, and whose range includes at least -2147483647 to +2147483647, inclusive (that is, -(2^31 - 1) to +(2^31 - 1)). This type can also be written as long int.
const long approx_seconds_per_year = 60L*60L*24L*365L;
The combination long dou...
A specifier that can be applied to the declaration of a non-static, non-reference data member of a class. A mutable member of a class is not const even when the object is const.
class C {
int x;
mutable int times_accessed;
public:
C(): x(0), times_accessed(0) {
}
int get...
In R, data objects are manipulated using named data structures. The names of the objects might be called "variables" although that term does not have a specific meaning in the official R documentation. R names are case sensitive and may contain alphanumeric characters(a-z,A-z,0-9), the dot...
This is a mistake that causes real confusion for Java beginners, at least the first time that they do it. Instead of writing this:
if (feeling == HAPPY)
System.out.println("Smile");
else
System.out.println("Frown");
they accidentally write this:
if (feeling == HAP...
5.6
PHP 5.6 introduced variable-length argument lists (a.k.a. varargs, variadic arguments), using the ... token before the argument name to indicate that the parameter is variadic, i.e. it is an array including all supplied parameters from that one onward.
function variadic_func($nonVariadic, ...$...
You can define the signing configuration to sign the apk in the build.gradle file.
You can define:
storeFile : the keystore file
storePassword: the keystore password
keyAlias: a key alias name
keyPassword: A key alias password
You have to define the signingConfigs block to create a signin...
You can define the signing configuration in an external file as a signing.properties in the root directory of your project.
For example you can define these keys (you can use your favorite names):
STORE_FILE=myStoreFileLocation
STORE_PASSWORD=myStorePassword
KEY_ALIAS=myKeyAlias
KEY_PASSWOR...
You can store the signing information setting environment variables.
These values can be accessed with System.getenv("<VAR-NAME>")
In your build.gradle you can define:
signingConfigs {
release {
storeFile file(System.getenv("KEYSTORE"))
storePasswo...
There are many querying operations on maps.
member :: Ord k => k -> Map k a -> Bool yields True if the key of type k is in Map k a:
> Map.member "Alex" $ Map.singleton "Alex" 31
True
> Map.member "Jenny" $ Map.empty
False
notMember is similar:
&g...
Inserting elements is simple:
> let m = Map.singleton "Alex" 31
fromList [("Alex",31)]
> Map.insert "Bob" 99 m
fromList [("Alex",31),("Bob",99)]
The Data.Map module in the containers package provides a Map structure that has both strict and lazy implementations.
When using Data.Map, one usually imports it qualified to avoid clashes with functions already defined in Prelude:
import qualified Data.Map as Map
So we'd then prepend Map funct...
