Tutorial by Examples: sin

using System.Linq.Expressions; // Create an expression tree. Expression<Func<int, bool>> exprTree = num => num < 5; // Decompose the expression tree. ParameterExpression param = (ParameterExpression)exprTree.Parameters[0]; BinaryExpression operation = (BinaryExpression)exp...

This code will subscribe to the emails observable twice: emails.Where(email => email.From == "John").Subscribe(email => Console.WriteLine("A")); emails.Where(email => email.From == "Mary").Subscribe(email => Console.WriteLine("B")); To share a...

NumberFormatInfo can be used for formatting both integer and float numbers. // invariantResult is "1,234,567.89" var invarianResult = string.Format(CultureInfo.InvariantCulture, "{0:#,###,##}", 1234567.89); // NumberFormatInfo is one of classes that implement IFormatProvider...

Snippet public class Person : INotifyPropertyChanged { private string _address; public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged(string propertyName) { PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName))...

A Stream is a sequence of elements upon which sequential and parallel aggregate operations can be performed. Any given Stream can potentially have an unlimited amount of data flowing through it. As a result, data received from a Stream is processed individually as it arrives, as opposed to performin...

Sorting lists Prior to Java 8, it was necessary to implement the java.util.Comparator interface with an anonymous (or named) class when sorting a list1: Java SE 1.2 List<Person> people = ... Collections.sort( people, new Comparator<Person>() { public int compare(Pe...

This example illustrates sending a String with value as "Some data!" from OriginActivity to DestinationActivity. NOTE: This is the most straightforward way of sending data between two activities. See the example on using the starter pattern for a more robust implementation. OriginActivit...

Examples of using Default Methods introduced in Java 8 in Map interface Using getOrDefault Returns the value mapped to the key, or if the key is not present, returns the default value Map<Integer, String> map = new HashMap<>(); map.put(1, "First element"); map.get(1); ...

When we create a button in layout, we can use the android:onClick attribute to reference a method in code to handle clicks. Button <Button android:width="120dp" android:height="wrap_content" android:text="Click me" android:onClick="handleCl...

When we create any View in layout, we can use the android:onClick attribute to reference a method in the associated activity or fragment to handle the click events. XML Layout <Button android:id="@+id/button" ... // onClick should reference the method in your activity or fra...

You can as well access other interface methods from within your default method. public interface Summable { int getA(); int getB(); default int calculateSum() { return getA() + getB(); } } public class Sum implements Summable { @Override public int get...

package com.example; import android.os.Bundle; import android.support.annotation.Nullable; import android.util.Log; import android.view.View; import android.view.ViewTreeObserver; public class ExampleActivity extends Activity { @Override protected void onCreate(@Nullable final ...

If you need to extract a part of string from the input string, we can use capture groups of regex. For this example, we'll start with a simple phone number regex: \d{3}-\d{3}-\d{4} If parentheses are added to the regex, each set of parentheses is considered a capturing group. In this case, we a...

As you use generic types with utility classes, you may often find that number types aren't very helpful when specified as the object types, as they aren't equal to their primitive counterparts. List<Integer> ints = new ArrayList<Integer>(); Java SE 7 List<Integer> ints = new A...

Let's say you want to define an interface that allows publishing / consuming data to and from different types of channels (e.g. AMQP, JMS, etc), but you want to be able to switch out the implementation details ... Let's define a basic IO interface that can be re-used across multiple implementations...

A Pattern can be compiled with flags, if the regex is used as a literal String, use inline modifiers: Pattern pattern = Pattern.compile("foo.", Pattern.CASE_INSENSITIVE | Pattern.DOTALL); pattern.matcher("FOO\n").matches(); // Is true. /* Had the regex not been compiled case...

Server: Start, and wait for incoming connections //Open a listening "ServerSocket" on port 1234. ServerSocket serverSocket = new ServerSocket(1234); while (true) { // Wait for a client connection. // Once a client connected, we get a "Socket" object // that c...

By default, any files that you save to Internal Storage are private to your application. They cannot be accessed by other applications, nor the user under normal circumstances. These files are deleted when the user uninstalls the application. To Write Text to a File String fileName= "hellowor...

By default, WebView does not implement JavaScript alert dialogs, ie. alert() will do nothing. In order to make you need to firstly enable JavaScript (obviously..), and then set a WebChromeClient to handle requests for alert dialogs from the page: webView.setWebChromeClient(new WebChromeClient() { ...

Once we've gotten the Connection, we will mostly use it to create Statement objects. Statements represent a single SQL transaction; they are used to execute a query, and retrieve the results (if any). Let's look at some examples: public void useConnection() throws SQLException{ Connection ...