ArcGIS Engine Developer Guide

JAVA APPLICATION PROGRAMMING INTERFACE
184 • ArcGIS Engine Developer Guide
scripts written in XML. You can either load these samples into your preferred
development environment or use the ANT scripts to compile and run them.
If you want to use ANT scripts, you should have a working ANT installation.
For the ArcGIS Engine samples, any ANT version 1.5.3 or higher will work. For
your convenience, a version of ant, called arcgisant, is included under the
ArcGIS\DeveloperKit\tools directory on Windows and the arcgis/developerkit/
tools directory on Solaris and Linux.
The ANT scripts included with the samples require certain additional environment
settings:
• ANT_HOME should point to your ANT installation directory. For example:
ANT_HOME=C:\ArcGIS\DeveloperKit\tools\ant
Solaris and Linux developers can source arcgis/developerkit/tools/
setenv_ant.csh or setenv_ant.sh, which sets this variable and includes arcgisant’s
bin directory in the PATH.
JRE
The ArcGIS Engine and Server developer kits include a version of the Java
Runtime Environment (JRE). This enables you to run any ArcGIS Java application
as long as all the necessary settings described above are local to the runtime.
You will notice the necessary *.dll files in the bin directory and the necessary *.jar
files in the library extension directory. All you need to do to get started with this
runtime environment is ensure that the bin directory is added to your PATH
environment variable:
PATH=...;\ArcGIS\java\jre\bin
JAVA PROGRAMMING TECHNIQUES
This section provides you with some fundamental concepts of the Java programming
language. It assumes you understand general programming concepts but are
relatively new to Java.
Features of the Java Virtual Machine
The JVM specification provides a platform-independent, abstract computer for
executing code. The JVM knows nothing about the Java language; instead, it
understands a particular binary format, the class file that contains instructions in
the form of bytecodes. The Java Virtual Machine specification provides an environment
that both compiles and interprets programs. The compiler takes a .java
file, produces a series of bytecodes, and stores them in a .class file, and the Java
interpreter executes the bytecodes stored in the .class file.
Each implementation of the JVM interacts with the operating system. The JVM
handles such things as memory allocation, garbage collection, and security monitoring.
Java Native Interfaces
Even though Java programs are designed to run on multiple platforms, there may
be times where the standard Java class library doesn’t support platform-dependent
features needed by a particular application or a Java program needs to implement
a lower-level program and have the Java program call it. The JNI is a standard
cross-platform programming interface provided by the Java language. It