Posts by Luhhh • 1,351 points
74 posts
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answers388
viewsQ: Non-nullable instance field '_Description' must be initialized
"Non-nullable instance field '_Description' must be initialized." As of version 2.12.0, Flutter always displays messages like this, how to solve this problem without downloading the version?…
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answers58
viewsQ: Cannot redeclare block-scoped variable error
Whenever I declare in typescript, a variable, like the one below, I get the following error: Cannot redeclare block-scoped variable let input1 = document.getElementById("input1") Searching google, I…
typescriptasked Luhhh 1,351 -
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answers17
viewsQ: Where to use typescript
Studying type script, I realized that it: 1- It is not a new language and yes, let’s say a plus/additional to Javascript, which adds some new concepts, I’m sure? 2 - Did I not understand where I…
typescriptasked Luhhh 1,351 -
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answers40
viewsQ: Select in two tables with Count
I have two tables in Mysql clientes id nome cat categorias id nome I need to create a SELECT, that shows all categories, but only categories that have more than 10 clients (for example). I wanted it…
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answer41
viewsQ: React: npx create-React-app vs referencing . js
What a difference when working with React, using the command npx create-react-app APP when simply creating a file html and reference libraries via script (.js)…
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answer259
viewsQ: Thymeleaf vs Angular
My searches say that Thymeleaf is a template engine that renders on the server, while Angular would be a front end framework, which renders on the client. I ask you. 1 - My search is correct, you…
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answers383
viewsQ: Change Bootstrap 4 button background
What would be the right way to change the background of a button in bootstrap 4 to a custom color: <button class="btn btn-primary btn-lg">Buscar</button> for <button class="btn…
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answer1039
viewsQ: async x await x Future
What are Keywords for async and await in Flutter? Some doubts I have are: 1 - They belong to Flutter or Dart? 2 - Why put the async at the end of the following method? void _method(TodoItem item)…
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answers146
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answer318
viewsQ: Entitystate - How it works
What would be and what is the Entity Framework Entitystate for? When can it be applied? Someone has some example of why to use it?
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answer277
viewsQ: LINQ to Entities x Lambda Expression
What is the difference between LINQ to Entities x Lambda Expression? Still using LINQ to Entities in the Entity Framework or is there something new?
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answer6800
viewsQ: Entity Framework Connection String
I am creating a project using Entity Framework. My question would be, how can I create a connectionString (for SQL Server for example) and set in my Dbcontext where it will get from the Web.config…
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answers70
viewsQ: Streaming PHP and HTML
I have a video in MP4. What I need is to stream this video via PHP (using for example an HTML player). Only that this transmision, needs to appear to be live (the user can not advance). Is there any…
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answer109
viewsQ: Xamarin Visual Studio
Installed Visual Studio with Xamarin, Android SDK, etc. When I compile the project it opens the Android AVD, but the Android System does not load, it is only a black screen.
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answers85
viewsQ: preg_replace to change image src
I have several news registered in a database, many of them, have images, that point directly to my site. Only they have http and as I have now installed SSL on my site, I need them to stay with…
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answers659
viewsQ: Know idle mouse time
I have an intranet system, which sellers attend some classes. Sometimes they leave the window open in that URL for days. The system via ajax, has a counter, so if the page is open, it keeps ordering…
javascriptasked Luhhh 1,351 -
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answer148
viewsQ: Mysql x Mongodb - Examples of Apps
Cite examples of applications, sites that would be best suited to use Mysql (or any other SGDB) or Mongodb. And the reason why? 'Cause I still can’t see scenarios where Mongodb is better..…
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answer8164
viewsQ: NPM --save doubt
What difference when installing a module via NPM, use --save? When using npm install product name, it installs the same and save the modules to the project folder. I didn’t understand then when to…
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answers3089
viewsQ: JS node - Mongodb x Mysql
Why every JS Node tutorial we see, is always shown example in Mongodb. What you both have that are so used? Why not use Mysql with Node?
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answer60
viewsQ: Mysql doubt in Select
I have a table of chats on mysql, the record of conversations between users. The fields are. id, id_from, id_to, message Example (My Data in DB): 1, 50, 10, 'Hello' 2, 10, 50, 'Nice?' 3, 50, 10,…
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answer46
viewsQ: Protect HTTP Requests with Android
I have an Android application, which requests Servlet or JSP files that return JSON. For example, in my application the user logs in and can add requests, when adding requests, the same is added via…
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answer50
viewsQ: Search XML tags
I have a string, similar to an XML document: <lists> <list name='NOVOS' values='1'> <list name='OLDS' values='2'> </lists> What I need to do is scan this code, and create an…
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answer88
viewsQ: Do Not Insert PHP and MYSQL Equal Values
I have a PHP and Mysql script that searches the client table for all clients that have not yet been imported to another database/table and imports. In the customer table, there’s a flag imported…
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answer8812
viewsQ: Angular JS Difference for Nodejs
What Angular JS Difference for Nodejs? Which is most used? Is there any tutorial that you recommend to those who are starting to teach a CRUD in each of them?
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answers557
viewsQ: First steps: Ionic
What I Need to Learn to Build Apps with Ionic? What language it uses? I wanted articles that show me the first steps.
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answers240
viewsQ: Keep Data Equal
I’m making a Chat on Android. I’m using Servlet (with JSON) + Oracle + Android. When I add a contact, for example, I save this contact in the Oracle database, via Servlet. But, when it comes to…
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answers3271
viewsQ: What is the difference between Listview and Recyclerview?
What difference between ListView and RecyclerView on Android? From which Api to RecyclerView is available? It is valid to use the RecyclerView and not the ListView?…
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answers337
viewsQ: V4 and V7 on Android
Why in some examples on the Internet, we find something like this: <android.support.v4.view.ViewPager/> <android.support.v7.view.ViewPager/> What would this V4 and V7 be? And in this…
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answers359
viewsQ: Firebase cloud messaging - Advantages
Besides having the possibility to work with messages, in the push Notifications style; What advantages do you see in the FCM? I’m talking about resources that really matter and help developers, and…
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answer559
viewsQ: Extract data from a facebook profile by searching for email
I need to check if there is profile on Facebook, passing as parameter the email. I noticed that the API has no way. But the facebook site has the URL: https://www.facebook.com/search/all/? q=@…
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answers248
viewsQ: How does development work for Xamarin?
If I want to create an app in Xamarin for Ios, I’m obliged to have a Mac? Xamarin creates a folder in the Android project and Ios, and what would be the folder for Windows Phone? Xamarin creates…
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answers6589
viewsQ: What is the file . env in Laravel 5?
What’s the file for .env? In the app.php has env => env('APP_ENV','production'). What would that be Production? What other string can go there? And the var APP_ENV? What does it mean?…
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answer91
viewsQ: Generator x Sequence in Firebird
When to use Generator and how much to use Sequence in Firebird? What difference between the two? There is a difference in performance?
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answers1309
viewsQ: Why put COMMIT at the end of the script using the Firebird database
Why in the Firebird database everything I do, including creating tables is necessary at the end of the script to give a command COMMIT?
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answers28
viewsQ: PHP Convert Video via API
Is there any API/Class in PHP that does file conversion? In this case the conversions would be: AVI to WEBM MP4 to WEBM WEBM for MP4
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answers380
viewsQ: Firebird - Tools
What tools are most used in Firebird management? I know Ibexpert, but he gets paid. There is something similar to Ibexpert, but free?
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answer404
viewsQ: Firebase Cloud Messaging x Google Cloud Messaging
What’s the difference between Firebase Cloud Messaging and Google Cloud Messaging? Both are free? Who keeps Firebase Cloud Messaging? What would be the best option?
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answer974
viewsQ: Search for content inside a file
I would like to create a php file and make it scan a directory and search for files. txt Scan for example all the . txt files from the /files/ folder (and all its Ubdirectories) Each file he scans I…
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answers181
viewsQ: Get latitude and longitude on Android
I’m creating an app on Android (with Android Studio) of Shopping. The idea is to register a purchase in the app that the user has performed. What I wanted is at the time we do that catch the…
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answers229
viewsQ: Store database links
I work with url friendly. All requests from my site, always goes through index.php There, I wanted to take the full url that someone is ordering and write to a bank table. As I have several…
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answers840
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viewsQ: Invoices not paid more than 10 days
I have a table of invoices and customers. In the invoice table, for example, I have the cliente_id, status and date fields In client table id, name, etc... What I need is to list all the invoices,…
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answer1310
viewsQ: Tabs on Android - How to create
how can I develop flaps in the style of Whatsapp. As the image below? Utilizo Android 5+…
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answer328
viewsQ: After logging in, prevent the app from returning to the login screen with the back button
In my login system, I type in the data and make it open a new Activity if the data is right. So far so good. But when I click back (the idea would be to close the application), it simply shows the…
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answers893
viewsQ: Friendly URL does not work with https
I use a .htaccess to use friendly url. Everything works perfectly. But, I installed an SSL certificate in my domain, also working, the whole site. But, when I type some url, which is not exactly the…
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answers53
viewsQ: MD5 is a safe hash?
MD5 is a safe hash? There is a way to reverse? If not the best option, what you recommend? I await suggestions... Thank you
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3
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answer840
viewsQ: How to make tabs similar to Whatsapp?
Does anyone have any example of how I can create this style of tabs on Android. In the image the example is the Whats App. I mean: 1 - CALL, Chats, Contacts tabs 2 - The Search bar, which is always,…
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answers302
viewsQ: Encryption/Decryption Android
Does anyone have an example of Encryption/Decryption on Android? And that has an interesting security? Remembering that I use the Java language in Android development.
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answer92
viewsQ: Mysql query with RAND
Is there any way I can bring Mysql records, where the field (for example) is_new is = 1, but when there are no records with the fields is_new = 1, I want the query to make an ORDER BY Rand(), it is…
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answer218
viewsQ: Registration Quantity per Data Mysql
I have the following scenario. I have a sales chart, there is a field data_vendas (datetime) and a field cliente_id Another client table, with the fields id, nome, data_cadastro etc.. What I need to…