alvin's blog

How to get help on Windows/DOS commands

Okay, this is one small step for me, and not really any steps for mankind ... I never know how to get help on Windows/DOS commands. I try command line options/switches like -h, -help, --help, /help, and \help, and of course none of them works.

Then somehow today I learned that the magic incantation, er, command line option, is /?, like this:

taskkill /?



A Java class that writes to and reads from a remote socket

I'm not going to describe this much today, but here's the source code for a Java class I put together from a number of other sources on the internet. In short, this code uses a Java Socket to connect to a port on a remote server, sends a command to that server to be executed, and then reads the output from the command that is executed. As a result, I assume that all information sent is text (nothing binary).

Java directories - How to determine the directory your Java application was started in

If you ever need to determine what directory your Java code is being run from (essentially the current working directory), you can get this information from the system properties, specifically the System.getProperty or System.getProperties methods.

The following line of Java code shows how to determine what directory your Java application was started in. This information is stored in the user.dir system property, which you access like this:

Ruby glob - how to process each file in a directory that matches a certain pattern

Here's some sample Ruby source code that shows how to do something with every file in a directory, where you only work on filenames that match a pattern you're interested in. For example, in my case I'm only interested in processing files that end with the filename extension WMA, so this first snippet of Ruby code shows how to print out the name of each file in a directory with the WMA extension:

How to search a Perl list for a pattern using grep

A lot of times when you're using Perl you have a list (or array), and you need to search that list for all strings that match a certain regular expression pattern (or regex). Fortunately Perl is built for this type of work, and it's straightforward to (a) perform this search, and (b) put your search results in another list.

How to increase the JScrollPane scrolling speed for mousewheel users

Java Swing FAQ: How do I increase the JScrollPane scrolling speed when using the mouse wheel?

Once you put a component (JTextArea, JEditorPane, JTable) into a JScrollPane in a Java Swing application, you'll quickly see that the default scrolling speed when trying to vertically scroll the viewport with the mousewheel is very slow. To make your scroll pane faster, i.e., more like a native Mac or Windows application, you'll want to increase this default mousewheel vertical scrolling speed.

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