Tutorial by Examples: ga

docker ps --filter name=myapp_1

In order to create a new Android HTTP Client HttpURLConnection, call openConnection() on a URL instance. Since openConnection() returns a URLConnection, you need to explicitly cast the returned value. URL url = new URL("http://example.com"); HttpURLConnection connection = (HttpURLConnect...

URL url = new URL("http://example.com"); HttpURLConnection connection = (HttpURLConnection) url.openConnection(); try { BufferedReader br = new BufferedReader(new InputStreamReader(connection.getInputStream())); // read the input stream // in this case, I simply read t...

HandleFunc registers the handler function for the given pattern in the server mux (router). You can pass define an anonymous function, as we have seen in the basic Hello World example: http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { fmt.Fprintln(w, "Hello, w...

The simplest way to create an error is by using the errors package. errors.New("this is an error") If you want to add additional information to an error, the fmt package also provides a useful error creation method: var f float64 fmt.Errorf("error with some additional informatio...

In Go, an error is represented by any value that can describe itself as string. Any type that implement the built-in error interface is an error. // The error interface is represented by a single // Error() method, that returns a string representation of the error type error interface { Erro...

In Go you don't raise an error. Instead, you return an error in case of failure. // This method can fail func DoSomething() error { // functionThatReportsOK is a side-effecting function that reports its // state as a boolean. NOTE: this is not a good practice, so this example // tur...

In Go errors can be returned from a function call. The convention is that if a method can fail, the last returned argument is an error. func DoAndReturnSomething() (string, error) { if os.Getenv("ERROR") == "1" { return "", errors.New("The method fai...

A Table View is a list of rows that can be selected. Each row is populated from a data source. This example creates a simple table view in which each row is a single line of text. Add a UITableView to your Storyboard Although there are a number of ways to create a UITableView, one of the easiest...

Sometimes you may want to start a new activity while removing previous activities from the back stack, so the back button doesn't take you back to them. One example of this might be starting an app on the Login activity, taking you through to the Main activity of your application, but on logging out...

A table can be replicated as follows: CREATE TABLE ClonedPersons LIKE Persons; The new table will have exactly the same structure as the original table, including indexes and column attributes. As well as manually creating a table, it is also possible to create table by selecting data from anot...

Adding elements: [1, 2, 3] << 4 # => [1, 2, 3, 4] [1, 2, 3].push(4) # => [1, 2, 3, 4] [1, 2, 3].unshift(4) # => [4, 1, 2, 3] [1, 2, 3] << [4, 5] # => [1, 2, 3, [4, 5]] Removing elements: array = [1, 2, 3, 4] array.pop # => 4 array # => [1, 2, 3] ...

While using scaffolding is a fast and easy if you are new to Rails or you are creating a new application, later it can be useful just to do it on your own ato avoid the need to go through the scaffold-generated code to slim it down (remove unused parts, etc.). Creating a model can be as simple as c...

Ruby on Rails provides a model generator you can use to create ActiveRecord models. Simply use rails generate model and provide the model name. $ rails g model user In addition to the model file in app/models, the generator will also create: the Test in test/models/user_test.rb the Fixtures ...

Ruby provides several ways to create a String object. The most common way is using single or double quotes to create a "string literal": s1 = 'Hello' s2 = "Hello" The main difference is that double-quoted string literals are a little bit more flexible as they support interpo...

With any variadic function, the function must know how to interpret the variable arguments list. With the printf() or scanf() functions, the format string tells the function what to expect. The simplest technique is to pass an explicit count of the other arguments (which are normally all the same ...

Use the following steps to create a topic: Click Create New Topic on the tag's dashboard. Name the topic. Provide detailed examples in the "Examples" section. If you have more to share, use the "Syntax," "Parameters," and "Remarks" sections. You have ...

It is possible to treat a GoogleMap as an Android view if we make use of the provided MapView class. Its usage is very similar to MapFragment. In your layout use MapView as follows: <com.google.android.gms.maps.MapView xmlns:android="http://schemas.android.com/apk/res/android" ...

Prefer public class Order { public OrderLine AddOrderLine(OrderLine orderLine) { if (orderLine == null) throw new ArgumentNullException(nameof(orderLine)); ... } } Over public class Order { public OrderLine AddOrderLine(OrderLine orderLine) { ...

You may need to convert a Stream emitting Optional to a Stream of values, emitting only values from existing Optional. (ie: without null value and not dealing with Optional.empty()). Optional<String> op1 = Optional.empty(); Optional<String> op2 = Optional.of("Hello World");...