NonStop Server for Java Programmer's Reference (NSJ 4.2+)

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Implementation Specifics
This section explains these subjects regarding HP implementations of NonStop Server for Java, based on Java 2
Platform, Standard Edition, SDK 1.4.2, for NonStop systems:
Headless Support●
Additional Files●
Additional Environment Variable●
Java Native Interface (JNI)●
IEEE Floating-Point Implementation●
Multithreaded Programming●
Java Print Service (JPS)●
Java Authentication and Authorization Service (JAAS)●
JavaBeans●
Debugging Java Programs●
Deviations in JVM Specification Options●
Garbage Collection (GC)●
Java GC Tuning●
JVM Tuning Tools●
Tuning Application Performance●
In addition, see Application Profiling.
Headless Support
Because the HP NonStop Kernel operating system does not provide support for windowing operations, NonStop
Server for Java 4 is a headless JVM that conforms to the Sun Microsystems headless support standard regarding
Java Abstract Window Toolkit (AWT) classes and methods. For similar reasons, the NonStop Server for Java 4
does not support the AppletViewer tool.
If your Java programs use classes and methods that require a display, keyboard, sound, or mouse operation, the
class or method will throw a HeadlessException if invoked when
GraphicsEnvironment.isHeadless returns true. This value is always true in NonStop Server for Java 4.
Classes and methods that support printing, fonts, and imaging are fully supported in a headless JVM.
While the Sun Microsystems documentation for the reference implementation states that you must set the system
property –Djava.awt.headless=true to run a headless JVM, setting this system property is unnecessary
for NonStop Server for Java 4.