Java Platform, Standard Edition

The Java Platform, Standard Edition or short Java SE ( German "Java Platform, Standard Edition " - to version 5.0, "Java 2 Platform, Standard Edition ", J2SE [ ˌ dʒeɪtu ː ˌ ɛsi ː ] ) is a collection of Java APIs. The Java SE is the basis for both the Java Platform, Enterprise Edition ( JEE ) by which applications are created for companies, as well as for simpler Java Platform, Micro Edition ( Java ME) for mobile devices. The current version 7 was released in 2011.

Version designations

The number " 2 " in J2SE stands for Java 2 Due to advances in version 1.2 of Java, Sun Microsystems in 1998, Java versions decided " Java 2 " apply to Java 1.2 as, came with version 6, but then returns to the original name " Java " or " Java SE" no trailing " 2" screen. The version numbers went through several changes: So was from version 1.5.0 ( released in September 2004) by omitting the preceding "1" " J2SE 5.0", with version 6 also renounced one still on the " .0 " at the end of the version number.

The following table summarizes the designations of the different Java versions once again:

Full version information is available in Java technology.

Programming interfaces

The Java SE 6 API consists of:

  • Long & util Base Libraries (see below)
  • Higher base libraries ( I / O, JNI, serialization, ... )
  • User Interface Toolkit ( AWT, Swing, Java 2D)
  • Integration Libraries (IDL, JDBC, JNDI, RMI, RMI -IIOP )

The most basic class libraries are defined java.lang and java.util in the packets, inputs and outputs in the package java.io. Following are the key packages and classes are briefly explained, for more information see the English original Javadoc documentation from Sun Microsystems.

Fundamental classes ( java.lang )

The package and its sub- packets java.lang defining classes that are needed for the basic mechanisms of the Java programming language.

  • The absolute base class Object, from which all other classes and interfaces are derived.
  • The metaclass class, which forms the basis for the mechanism of self-reflection ( Reflection).
  • Wrapper around basic data types such as Boolean, Character, or Integer.
  • The String class for strings.
  • The class system is used to read environment variables and so-called system properties. The system properties are system properties, such as the version of the Java runtime environment. It can also be defined on the command line when calling the Java program, any additional " System Properties."

The abbreviation "long " stands for English language, ie " language " because it is fundamental to the programming language.

Classes for data structures, time, and internationalization ( java.util )

The java.util package contains several classes are defined, the less fundamental than which, although defined in java.lang, but are also needed for virtually any Java program. The abbreviation " util " stands for English utility, which translates as "utility" means.

  • A lot of so-called collection classes, constituting a hierarchy of data structures implemented finished.
  • The Date class that represents a point in time and the Calendar class, can perform calendar calculations.
  • The class ResourceBundle ( German " resource bundle "), which represents a set of so-called "Resources". Resources in this sense are text, images and other objects that can be customized for different language versions of the program. This allows the development of programs for use in different countries without the actual program code for each country must be changed.
  • The Properties class that can read, among other things named string values ​​from a text file. These text files are named Java properties files and are often used as a simple configuration mechanism. They are also an implementation of the resource bundle based.
  • The java.util.zip package contains classes that can generate and process compressed files. It supports formats ZIP and gzip or their compression algorithms.
  • The java.util.jar package supports the production and processing of Java archive ( JAR ) files.
  • The package java.util.regex supports regular expressions ( regular expressions ) for finding patterns in strings. The String class uses this functionality, for example in a method " matches".

Classes for input and output ( java.io )

The java.io package contains classes for input and output (English input and output, therefore, "io " ), mainly so-called streams ( German " (data) flows" ).

  • The abstract class InputStream is the base class for all input streams. This example, to read input from the keyboard or from a file.
  • The abstract class OutputStream is the base class for all output streams. This for example, write characters to the screen or to a file.
  • The streams were introduced in the first version of Java and process bytes. Especially for the input and output of Unicode character classes Reader ( German " reader " ) and Writer ( German " writer " ) were introduced later.

Other important packages

  • Java.awt - Abstract Window Toolkit, graphics output and use of graphical user interfaces
  • Java.nio - Advanced functions for input and output, allowing more efficient implementation
  • Java.net - URLs, Socket and other classes to access computer networks
  • Java.rmi - Remote Method Invocation for remote method calls
  • Java.text - formatting of dates, numbers, and other
  • Java.math - integers and fixed-point numbers with unlimited precision
  • Javax.net - contains an abstract factory for creating specialized Sockets
  • Javax.naming - JNDI access to naming services
  • Javax.print - Output to printer
  • Javax.swing - Swing, advanced GUI components
  • Javax.xml.bind - XML binding using JAXB
  • Javax.xml.stream - Streaming API for XML pull parser for XML
  • Javax.xml.xpath - Processing of XPath expressions
  • Org.w3c.dom - Document Object Model for representation of XML documents as a tree of objects
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