Tutorial by Examples: ti

Multiple threads with one shared object

In this example we have only one object but it is shared between/executed on different threads. Ordinary usage of fields to save state would not be possible because the other thread would see that too (or probably not see). public class Test { public static void main(String[] args) { ...

Java Language • ThreadLocal

Reduction with Streams

Reduction is the process of applying a binary operator to every element of a stream to result in one value. The sum() method of an IntStream is an example of a reduction; it applies addition to every term of the Stream, resulting in one final value: This is equivalent to (((1+2)+3)+4) The reduc...

Java Language • Streams

Initializing static final fields using a static initializer

To initialize a static final fields that require using more than a single expression, a static initializer can be used to assign the value. The following example initializes a unmodifiable set of Strings: public class MyClass { public static final Set<String> WORDS; static {...

Java Language • Classes and Objects

Differences between Java SE JRE or Java SE JDK distributions

Sun / Oracle releases of Java SE come in two forms: JRE and JDK. In simple terms, JREs support running Java applications, and JDKs also support Java development. Java Runtime Environment Java Runtime Environment or JRE distributions consist of the set of libraries and tools needed to run and mana...

Java Language • Java Editions, Versions, Releases and Distributions

What is the difference between Oracle Hotspot and OpenJDK

Orthogonal to the JRE versus JDK dichotomy, there are two types of Java release that are widely available: The Oracle Hotspot releases are the ones that you download from the Oracle download sites. The OpenJDK releases are the ones that are built (typically by third-party providers) from the Ope...

Java Language • Java Editions, Versions, Releases and Distributions

Setting Variables

Here are some ways to set variables: You can set a variable to a specific, string, number, date using SET EX: SET @var_string = 'my_var'; SET @var_num = '2' SET @var_date = '2015-07-20'; you can set a variable to be the result of a select statement using := EX: Select @var := '123'; (...

MySQL • Using Variables

Abbreviation

To mark some expression as an abbreviation, use <abbr> tag: <p>I like to write <abbr title="Hypertext Markup Language">HTML</abbr>!</p> If present, the title attribute is used to present the full description of such abbreviation.

HTML • Text Formatting

Introduction into queries

Source table RowABCD1CodeProductColourPrice21penred50032penblue-5043penred054pencilblue1765pencilgreen-1.5 to select all: = QUERY(A1:D5, "select *") or = QUERY(A1:D5, "select A, B, C, D") or convert data range into array and use this formula: = QUERY({A1:D5}, "sel...

google-spreadsheet • Query Function

Delegate to a class without providing it in the public constructor

Assume you want to delegate to a class but you do not want to provide the delegated-to class in the constructor parameter. Instead, you want to construct it privately, making the constructor caller unaware of it. At first this might seem impossible because class delegation allows to delegate only to...

Kotlin • Idioms

Creating new structures for data

Struct defines new classes with the specified attributes and accessor methods. Person = Struct.new :first_name, :last_name You can then instantiate objects and use them: person = Person.new 'John', 'Doe' # => #<struct Person first_name="John", last_name="Doe"> p...

Ruby Language • Struct

Creating an unbound service

The first thing to do is to add the service to AndroidManifest.xml, inside the <application> tag: <application ...> ... <service android:name=".RecordingService" <!--"enabled" tag specifies Whether or not the service can ...

Android • Service

Do Notation

Any list comprehension can be correspondingly coded with list monad's do notation. [f x | x <- xs] f <$> xs do { x <- xs ; return (f x) } [f x | f <- fs, x <- xs] fs <*> xs do { f <- fs ; x <- xs ; return (f x) } [y | x &...

Haskell Language • List Comprehensions

Are 2 line segments intercepting?

The function in this example returns true if two line segments are intersecting and false if not. The example is designed for performance and uses closure to hold working variables // point object: {x:, y:} // p0 & p1 form one segment, p2 & p3 form the second segment // Retur...