Enhancements in
Packages java.lang.* and java.util.*
- ProcessBuilder
- The new
ProcessBuilder class provides a more
convenient way to invoke subprocesses than does
Runtime.exec. In particular, ProcessBuilder makes it easy to
start a subprocess with a modified process environment (that is,
one based on the parent's process environment, but with a few
changes).
- Threads - The
java.lang.Thread class has
the following enhancements:
- Thread priority
handling has changed.
Thread.State
enum class and the new getState()
API are provided for querying the execution state of a thread.- The new thread dump API - The
getStackTrace
and getAllStackTraces
methods in the Thread class - provides a programmatic
way to obtain the stack trace of a thread or all threads.
- The
uncaughtExceptionHandler mechanism, previously
available only through the ThreadGroup class, is now available
directly through the Thread class.
- A new form of the
sleep() method is provided which
allows for sleep times smaller than one millisecond.
- Instrumentation
- The new
java.lang.instrument
package provides services that allow Java programming agents to
instrument programs running on the Java virtual machine by
modifying methods' bytecodes at runtime.
- Formatter - An
interpreter for printf-style format strings, the
Formatter class provides support for layout
justification and alignment, common formats for numeric, string,
and date/time data, and locale-specific output. Common Java types
such as byte, java.math.BigDecimal
, and java.util.Calendar
are supported. Limited formatting customization for arbitrary user
types is provided through the java.util.Formattable
interface.
- Scanner - The
java.util.Scanner class can be used to convert text
into primitives or Strings. Since it is based on the
java.util.regex
package, it also offers a way to conduct regular expression based
searches on streams, file data, strings, or implementors of the
Readable
interface.
- Collections Framework
Enhancements - There are many enhancements to the
Collections framework.
- Chained Exception
Facility - This is a new facility that provides a common
API to record the fact that one exception caused another, to access
causative exceptions, and to acess the entire "causal chain" as
part of the standard stack backtrace, ensuring that preexisting
programs will provide this information with no additional effort on
the part of their authors.
- String
- Two
split methods are new. The
subSequence method has been added, as required by the
CharSequence interface that String now
implements. Three additional methods have been added:
matches, replaceAll, and
replaceFirst.
- StringBuffer
- The
subSequence method has been added, as required
by the CharSequence interface that
StringBuffer now implements.
- Thread
- The
interrupt method has been revised to interrupt
threads blocked in channel-I/O operations.
- Logging API - The
Java Logging API facilitates software servicing and maintenance at
customer sites by producing log reports suitable for analysis by
end users, system administrators, field service engineers, and
software development teams. The Logging APIs capture information
such as security failures, configuration errors, performance
bottlenecks, and/or bugs in the application or platform. The core
package includes support for delivering plain text or XML formatted
log records to memory, output streams, consoles, files, and
sockets. In addition, the logging APIs are capable of interacting
with logging services that already exist on the host operating
system.
- Preferences API
- The preferences API, implemented by package
java.util.prefs,
allows applications to store and retrieve user and system
preference and configuration data. This data is stored persistently
in an implementation-dependent backing store. The Preferences API
is intended to replace most common uses of class
java.util.Properties, rectifying many of its
deficiencies, while retaining its light weight.
- java.lang.Math and
java.lang.StrictMath - Two new classes which provide APIs
for performing general numeric operations.
java.lang.StrictMath
- Class java.lang.StrictMath has the same API as old
class java.lang.Math, which was present in previous
versions of the Java platform. Unlike class Math,
however, StrictMath is defined to return bit-for-bit
reproducible results in all implementations.java.lang.Math
- Class java.lang.Math provides the same set of API as
does class StrictMath. However, unlike some of the
numeric functions of class StrictMath, all
implementations of the equivalent functions of class
Math are not defined to return the bit-for-bit same
results, but can vary within specified constraints. This permits
better-performing implementations where strict reproducibility is
not required.
- Timer API - Two new
classes to provide an API for a timer facility which can be used
for purposes such as animations, human interaction timeouts,
on-screen clocks and calendars, work-scheduling routines, reminder
facilities, and more.
Countdown.java is a
simple demo application that uses the Timer API.
- Virtual Machine Shutdown
Hooks Sophisticated applications often require the ability
to perform specific actions when the virtual machine shuts down,
whether due to voluntary exit or involuntary termination. Typical
actions include cleanly closing down network connections, saving
session state, and deleting temporary files. Every major operating
system provides the means for native applications to do this,
though of course the details vary from platform to platform. Three
methods have been added to
java.lang.Runtime to
provide a simple and portable interface to these facitilies. The
new methods are:
In addition, the Runtime.exit
method has been revised. For more information, see Design of the Shutdown Hooks API.
- Enhanced Collections
Framework - The Collections Framework has these new
convenience APIs:
- Added
Collections.singletonList and Collections.singletonMap.
Previously, there was a convenience implementation for singleton
Set, but no corresponding implementation for List and Map. Both of
these implementations proved desirable in practice.
- Added Collections.EMPTY_MAP.
Previously, there were constant convenience implementations for the
empty Set and List, but no corresponding implementation for
Map.
The following special-purpose implementation has also been added:
- Added
Map constuctor for WeakHashMap. The Map interface dictates that
most Map implementations should have a "copy constructor" that
takes a Map argument. WeakHashMap lacked such a constructor in the
1.2 release.
- New URL JAR File
Caching - The API of classes
java.util.zip and
java.util.jar have been enhanced with the addition of
the following:
The previous implementation of caching downloaded Jar files created
problems for long-running server application and for RMI. Each open
JarURLConnection creates a temporary local file that
holds Jar-file date, and a JarFile object is created on top of the
temporary file. Because the open file handle/descriptor on each
temporary file was never closed, the files could quickly take up
disk space for long-running server applications. The new API
provides a solution for this problem by supporting a new
"delete-on-close" mode for opening Zip and Jar files.
