| Issue |
Subject |
Date |
| 178
|
WalkingCollection
We look at how we could internalize the iteration into
a collection by introducing a Processor interface that
is applied to each element. This allows us to manage
concurrency from within the collection.
|
2009-11-14
|
| 175
|
Creating Objects Without Calling Constructors
De-Serialization creates objects without calling
constructors. We can use the same mechanism to create
objects at will, without ever calling their constructors.
|
2009-09-08
|
| 172
|
Wonky Dating
The DateFormat produces some seemingly unpredictable
results parsing the date 2009-01-28-09:11:12 as
"Sun Nov 30 22:07:51 CET 2008". In this newsletter we
examine why and also show how DateFormat reacts to
concurrent access.
|
2009-04-23
|
| 171
|
Throwing ConcurrentModificationException Early
One of the hardest exceptions to get rid of in a system is
th ConcurrentModificationException, which typically occurs
when a thread modifies a collection whilst another is busy
iterating. In this newsletter we show how we can fail on
the modifying, rather than the iterating thread.
|
2009-03-09
|
| 166
|
Serialization Cache
Java's serialization mechanism is optimized for immutable
objects. Writing objects without resetting the stream
causes a memory leak. Writing a changed object twice
results in only the first state being written. However,
resetting the stream also loses the optimization stored in
the stream.
|
2008-11-30
|
| 154
|
ResubmittingScheduledPoolExecutor
Timers in Java have suffered from the typical Command
Pattern characteristics. Exceptions could stop the timer
altogether and even with the new ScheduledPoolExecutor,
a task that fails is cancelled. In this newsletter we
explore how we could reschedule periodic tasks
automatically.
|
2007-12-04
|
| 153
|
Timeout on Console Input
In this newsletter, we look at how we can read from the
console input stream, timing out if we do not get a
response by some timeout.
|
2007-11-25
|
| 139
|
Mustang ServiceLoader
Mustang introduced a ServiceLoader than can be used to
load JDBC drivers (amongst others) simply by including a
jar file in your classpath. In this newsletter, we look at
how we can use this mechanism to define and load our own
services.
|
2007-02-10
|
| 137
|
Creating Loggers DRY-ly
A common idiom for logging is to create a logger in each class
that is based on the class name. The name of the class is
then duplicated in the class, both in the class definition and
in the logger field definition, since the class is for some
reason not available from a static context. Read how to solve
that problem.
|
2006-12-28
|
| 136
|
Sneaking in JDBC Drivers
In this newsletter, we look at a technique of how we can
replace an existing database driver with our own one. This
could be used to migrate an application to a new database
where you only have the compiled classes. Or it could be used
to insert a monitoring JDBC connection that measures the
length of database queries.
|
2006-12-11
|
| 132
|
Thread Dump JSP in Java 5
Sometimes it is useful to have a look at what the threads are
doing in a light weight fashion in order to discover tricky
bugs and bottlenecks. Ideally this should not disturb the
performance of the running system. In addition, it should be
universally usable and cost nothing. Have a look at how we do
it in this newsletter.
|
2006-09-11
|
| 131
|
Sending Emails from Java
In this newsletter, we show how simple it is to send
emails from Java. This should obviously not be used for
sending unsolicited emails, but will nevertheless illustrate
why we are flooded with SPAM.
|
2006-08-28
|
| 128
|
SuDoKu Madness
In this Java Specialists' Newsletter, we look at a
simple Java program that solves SuDoKu puzzles.
|
2006-06-21
|
| 122
|
Copying Files from the Internet
Sometimes you need to download files using HTTP from a machine
that you cannot run a browser on. In this simple Java program
we show you how this is done. We include information of your
progress for those who are impatient, and look at how the
volatile keyword can be used.
|
2006-03-08
|
| 118
|
A Simple Database Viewer
A simple database viewer written in Java Swing that
reads the metadata and shows you all the tables and contents
of the tables, written in under 100 lines of Java code,
including comments.
|
2005-12-19
|
| 116
|
Closing Database Statements
Don't Repeat Yourself. The mantra of the good Java
programmer. But database code often leads to this
antipattern. Here is a neat simple solution from the
Jakarta Commons DbUtils project.
|
2005-11-28
|
| 086b
|
Initialising Fields before Superconstructor call (Follow-up)
|
2004-03-20
|
| 086
|
Initialising Fields before Superconstructor call
|
2004-03-19
|
