Java AWT Native Interface is an interface for the Java programming language

Java (programming language)

Java is a programming language originally developed by James Gosling at Sun Microsystems and released in 1995 as a core component of Sun Microsystems' Java platform. The language derives much of its syntax from C and C++ but has a simpler object model and fewer low-level facilities...

 that enables rendering

Rendering (computer graphics)

Rendering is the process of generating an image from a model , by means of computer programs. A scene file contains objects in a strictly defined language or data structure; it would contain geometry, viewpoint, texture, lighting, and shading information as a description of the virtual scene...

 libraries

Library (computer science)

In computer science, a library is a collection of resources used to develop software. These may include pre-written code and subroutines, classes, values or type specifications....

 compiled to native code to draw directly to a Java Abstract Window Toolkit

Abstract Window Toolkit

The Abstract Window Toolkit is Java's original platform-independent windowing, graphics, and user-interface widget toolkit. The AWT is now part of the Java Foundation Classes — the standard API for providing a graphical user interface for a Java program.AWT is also the GUI toolkit for a...

 (AWT) object

Object (computer science)

In computer science, an object is any entity that can be manipulated by the commands of a programming language, such as a value, variable, function, or data structure...

 drawing surface.

The Java Native Interface

Java Native Interface

The Java Native Interface is a programming framework that enables Java code running in a Java Virtual Machine to call and to be called by native applications and libraries written in other languages such as C, C++ and assembly.-Purpose and features:JNI enables one to write native methods to...

 (JNI) enabled developers to add platform-dependent functionality to Java applications

Application software

Application software, also known as an application or an "app", is computer software designed to help the user to perform specific tasks. Examples include enterprise software, accounting software, office suites, graphics software and media players. Many application programs deal principally with...

. The JNI enables developers to add time-critical operations like mathematical calculations and 3D rendering

3D rendering

3D rendering is the 3D computer graphics process of automatically converting 3D wire frame models into 2D images with 3D photorealistic effects on a computer.-Rendering methods:...

. Previously, native 3D rendering was a problem because the native code didn't have access to the graphic context. The AWT Native Interface is designed to give developers access to an AWT Canvas for direct drawing by native code. In fact, the Java 3D

Java 3D

Java 3D is a scene graph-based 3D application programming interface for the Java platform. It runs atop either OpenGL or Direct3D. Since version 1.2, Java 3D has been developed under the Java Community Process....

 API extension to the standard Java SE JDK relies heavily on the AWT Native Interface to render 3D objects in Java. The AWT Native Interface is very similar to the JNI, and, the steps are, in fact, the same as those of the JNI. See the Java Native Interface

Java Native Interface

The Java Native Interface is a programming framework that enables Java code running in a Java Virtual Machine to call and to be called by native applications and libraries written in other languages such as C, C++ and assembly.-Purpose and features:JNI enables one to write native methods to...

 article for an explanation of the JNI techniques employed by the AWT Native Interface.

The AWT Native Interface was added to the Java platform with the J2SE

Java Platform, Standard Edition

Java Platform, Standard Edition or Java SE is a widely used platform for programming in the Java language. It is the Java Platform used to deploy portable applications for general use...

 1.3 ("Kestrel") version.

AWT Native Interface steps

A complete walkthrough example of this technology is available on Wikibooks (see link below).

Create a Java application

See the Java Native Interface

Java Native Interface

The Java Native Interface is a programming framework that enables Java code running in a Java Virtual Machine to call and to be called by native applications and libraries written in other languages such as C, C++ and assembly.-Purpose and features:JNI enables one to write native methods to...

 article for an explanation of the native keyword

Keyword (computer programming)

In computer programming, a keyword is a word or identifier that has a particular meaning to the programming language. The meaning of keywords — and, indeed, the meaning of the notion of keyword — differs widely from language to language....

 and the loadLibrary method. A paint method will be simply invoked when the AWT event dispatching thread

Event dispatching thread

The event dispatching thread is a background thread used in Java to process events from the Abstract Window Toolkit graphical user interface event queue. These events are primarily update events that cause user interface components to redraw themselves, or input events from input devices such as...

 "repaints" the screen.

Create a C++ header file

Create the C++

C++

C++ is a statically typed, free-form, multi-paradigm, compiled, general-purpose programming language. It is regarded as an intermediate-level language, as it comprises a combination of both high-level and low-level language features. It was developed by Bjarne Stroustrup starting in 1979 at Bell...

 header file

Header file

Some programming languages use header files. These files allow programmers to separate certain elements of a program's source code into reusable files. Header files commonly contain forward declarations of classes, subroutines, variables, and other identifiers...

 as usual (See Java Native Interface

Java Native Interface

The Java Native Interface is a programming framework that enables Java code running in a Java Virtual Machine to call and to be called by native applications and libraries written in other languages such as C, C++ and assembly.-Purpose and features:JNI enables one to write native methods to...

 for more complete explanations.)

Implement the C++ native code

Type this in a file named "NativeSideCanvas.cpp" and compile into a library. See Java Native Interface

Java Native Interface

The Java Native Interface is a programming framework that enables Java code running in a Java Virtual Machine to call and to be called by native applications and libraries written in other languages such as C, C++ and assembly.-Purpose and features:JNI enables one to write native methods to...

 for a more complete explanation. (For Solaris

Solaris Operating System

Solaris is a Unix operating system originally developed by Sun Microsystems. It superseded their earlier SunOS in 1993. Oracle Solaris, as it is now known, has been owned by Oracle Corporation since Oracle's acquisition of Sun in January 2010....

 code and other operating systems see links below.)

Run the program

One should run the file as usual. One should then see a window with, for example, a rectangle drawn in it. (See Java Native Interface

Java Native Interface

The Java Native Interface is a programming framework that enables Java code running in a Java Virtual Machine to call and to be called by native applications and libraries written in other languages such as C, C++ and assembly.-Purpose and features:JNI enables one to write native methods to...

 for complete instructions.)

Note: One can notice that the AWT Native Interface requires the "jawt.dll" (or "jawt.so") to run with the application, so the easiest way to do that is copying the "jawt.dll" (should be in the .../jre/bin file path of the JDK's installation path.)

Native painting

One can paint as if it is a native application. In Windows

Microsoft Windows

Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

, the JVM will pass a HWND and other window information to the native application so that the application will "know" where to draw. It could use GDI to draw a Rectangle. The window information the native side needs will be in a JAWT_Win32DrawingSurfaceInfo structure (depending on Operating System

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

) which can be retrieved with this line: dsi_win = (JAWT_Win32DrawingSurfaceInfo*)dsi->platformInfo;

See also

• Java Native Interface
  Java Native Interface
  The Java Native Interface is a programming framework that enables Java code running in a Java Virtual Machine to call and to be called by native applications and libraries written in other languages such as C, C++ and assembly.-Purpose and features:JNI enables one to write native methods to...
  
  
• Abstract Window Toolkit
  Abstract Window Toolkit
  The Abstract Window Toolkit is Java's original platform-independent windowing, graphics, and user-interface widget toolkit. The AWT is now part of the Java Foundation Classes — the standard API for providing a graphical user interface for a Java program.AWT is also the GUI toolkit for a...
  
  
• Event dispatching thread
  Event dispatching thread
  The event dispatching thread is a background thread used in Java to process events from the Abstract Window Toolkit graphical user interface event queue. These events are primarily update events that cause user interface components to redraw themselves, or input events from input devices such as...
  
  
• Java Swings, a Wikibook about graphic programming in Java

External links

• The AWT Native Interface