Tutorial by Examples: a

The following rules define a simple strategy for creating immutable objects. Don't provide "setter" methods - methods that modify fields or objects referred to by fields. Make all fields final and private. Don't allow subclasses to override methods. The simplest way to do this is to d...

public final class Color { final private int red; final private int green; final private int blue; private void check(int red, int green, int blue) { if (red < 0 || red > 255 || green < 0 || green > 255 || blue < 0 || blue > 255) { throw ...

In this case class Point is mutable and some user can modify state of object of this class. class Point { private int x, y; public Point(int x, int y) { this.x = x; this.y = y; } public int getX() { return x; } public void setX(int ...

The advantage of immutability comes with concurrency. It is difficult to maintain correctness in mutable objects, as multiple threads could be trying to change the state of the same object, leading to some threads seeing a different state of the same object, depending on the timing of the reads and ...

require 'date' date1 = Date.parse "01/06/2016" date2 = Date.parse "05/06/2016" p "Period #{date1.strftime("%d/%m/%Y")} to #{date2.strftime("%d/%m/%Y")}" (date1..date2).each do |date| p date.strftime("%d/%m/%Y") end # "...

$ provides an easy and a concise method to concatenate multiple strings. var str1 = "text1"; var str2 = " "; var str3 = "text3"; string result2 = $"{str1}{str2}{str3}"; //"text1 text3"

Since BackAndroid is deprecated. Use BackHandler instead of BackAndroid. import { BackHandler } from 'react-native'; {...} ComponentWillMount(){ BackHandler.addEventListener('hardwareBackPress',()=>{ if (!this.onMainScreen()) { this.goBack(); return true; ...

<?php include "vendor/autoload.php"; $app = new \Slim\App(); $app->get('/hello', function () { echo "Hello, world"; }); $app->run();

In the following example echo on will take effect after the end of the brackets context is reached: @echo off ( echo on echo ## ) echo $$ In order to "activate" echo on in a brackets context (including FOR and IF commands) you can use FOR /f macro : @echo off setlocal ...

Anonymous functions technique uses the fact that CALL command uses internally GOTO when subroutine is called and abusing help message printing with variable double expansion: @echo off setlocal set "anonymous=/?" call :%%anonymous%% a b c 3>&1 >nul if "%0" == ...

Lets have the following file called library.cmd : @echo off echo -/-/- Batch Functions Library -/-/- :function1 echo argument1 - %1 goto :eof To execute only the :function1 without the code of the rest of the file you should put a label :function1 in the caller bat and use it lik...

import java.util.StringTokenizer; public class Simple{ public static void main(String args[]){ StringTokenizer st = new StringTokenizer("apple ball cat dog"," "); while (st.hasMoreTokens()) { System.out.println(st.nextToken()); } } ...

public static void main(String args[]) { StringTokenizer st = new StringTokenizer("apple,ball cat,dog", ","); while (st.hasMoreTokens()) { System.out.println(st.nextToken()); } } Output: apple ball cat dog

Semaphores are used to synchronize operations between two or more processes. POSIX defines two different sets of semaphore functions: 'System V IPC' — semctl(), semop(), semget(). 'POSIX Semaphores' — sem_close(), sem_destroy(), sem_getvalue(), sem_init(), sem_open(), sem_post(), sem_try...

Parent element html <child-component [isSelected]="inputPropValue"></child-component> Parent element ts export class AppComponent { inputPropValue: true } Child component ts: export class ChildComponent { @Input() inputPropValue = false; } Child compone...

The most effective way to resolve curl to a different server is to use the --resolve option. This option will insert the address into curl's DNS cache, so it will effectively make curl believe that's the address it got when it resolved the name. Like so: curl --resolve eaxmple.com:80:1.2.3.4 http:...

The "Host:" header is a normal way an HTTP client tells the HTTP server which server it speaks to. By passing custom modified "Host:" header you can have the server respond with the content of the site, even if you didn't actually connect to the host name. For example, if you ha...

Lets have the following example.bat and call it with arguments 1 ,2 and 3: @echo off ( shift shift echo %1 ) As the variable expansion will change after the the end brackets context is reached the output will be: 1 As this might be an issue when shifting inside brackets ...

from django.contrib.auth.models import User class UserAdmin(admin.ModelAdmin): list_display = ('email', 'first_name', 'last_name') list_filter = ('is_staff', 'is_superuser') admin.site.unregister(User) admin.site.register(User, UserAdmin) We need to unregister before regis...

First is first, ensure that USE_TZ = True in your settings.py file. Also set a default time zone value to TIME_ZONE such as TIME_ZONE='UTC'. View a complete list of timezones here. If USE_TZ is False, TIME_ZONE will be the time zone that Django will use to store all datetimes. When USE_TZ is enable...