Tutorial by Examples: st

string helloWorld = "Hello World!"; string world = helloWorld.Substring(6); //world = "World!" string hello = helloWorld.Substring(0,5); // hello = "Hello" Substring returns the string up from a given index, or between two indexes (both inclusive).

string HelloWorld = "Hello World"; HelloWorld.StartsWith("Hello"); // true HelloWorld.StartsWith("Foo"); // false Finding a string within a string Using the System.String.Contains you can find out if a particular string exists within a string. The method returns ...

String.Trim() string x = " Hello World! "; string y = x.Trim(); // "Hello World!" string q = "{(Hi!*"; string r = q.Trim( '(', '*', '{' ); // "Hi!" String.TrimStart() and String.TrimEnd() string q = "{(Hi*"; string r = q.TrimStart( '{...

Unlike interfaces, which can be described as contracts for implementation, abstract classes act as contracts for extension. An abstract class cannot be instantiated, it must be extended and the resulting class (or derived class) can then be instantiated. Abstract classes are used to provide generi...

Use the String.Format() method to replace one or more items in the string with the string representation of a specified object: String.Format("Hello {0} Foo {1}", "World", "Bar") //Hello World Foo Bar

All six methods return a single value of the sequence type, and can be called with or without a predicate. Depending on the number of elements that match the predicate or, if no predicate is supplied, the number of elements in the source sequence, they behave as follows: First() Returns the fir...

Event declaration: public event EventHandler<EventArgsT> EventName; Event handler declaration: public void HandlerName(object sender, EventArgsT args) { /* Handler logic */ } Subscribing to the event: Dynamically: EventName += HandlerName; Through the Designer: Click the Events...

Events can be of any delegate type, not just EventHandler and EventHandler<T>. For example: //Declaring an event public event Action<Param1Type, Param2Type, ...> EventName; This is used similarly to standard EventHandler events: //Adding a named event handler public void HandlerNa...

There are several places where you can use String.Format indirectly: The secret is to look for the overload with the signature string format, params object[] args, e.g.: Console.WriteLine(String.Format("{0} - {1}", name, value)); Can be replaced with shorter version: Console.WriteLine...

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...

class Example { public string Foobar { get; set; } public List<string> Names { get; set; } public Example() { Foobar = "xyz"; Names = new List<string>(){"carrot","fox","ball"}; } }

Create a new file in your text editor or IDE named HelloWorld.java. Then paste this code block into the file and save: public class HelloWorld { public static void main(String[] args) { System.out.println("Hello, World!"); } } Run live on Ideone Note: For Java to r...

Say we have a button (we can create it programmatically, or bind it from a view using findViewbyId(), etc...) Button btnOK = (...) Now, create an anonymous class and set it inline. btnOk.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { ...

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...

Collect with toList() and toSet() Elements from a Stream can be easily collected into a container by using the Stream.collect operation: System.out.println(Arrays .asList("apple", "banana", "pear", "kiwi", "orange") .stream() .filter...

We can create an ArrayList (following the List interface): List aListOfFruits = new ArrayList(); Java SE 5 List<String> aListOfFruits = new ArrayList<String>(); Java SE 7 List<String> aListOfFruits = new ArrayList<>(); Now, use the method add to add a String: ...

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...

An abstract class is a class marked with the abstract keyword. It, contrary to non-abstract class, may contain abstract - implementation-less - methods. It is, however, valid to create an abstract class without abstract methods. An abstract class cannot be instantiated. It can be sub-classed (exten...

This example will start DestinationActivity from OriginActivity. Here, the Intent constructor takes two parameters: A Context as its first parameter (this is used because the Activity class is a subclass of Context) The Class of the app component to which the system should deliver the Intent (i...

Under most circumstances, it is simpler from a code-design standpoint to use existing generic Exception classes when throwing exceptions. This is especially true if you only need the exception to carry a simple error message. In that case, RuntimeException is usually preferred, since it is not a che...