JavaDoc Cheat Sheet

  • The first sentence of each doc comment should be a summary sentence
  • Write the description to be implementation-independent, but specifying such dependencies where necessary. (what is required, what is allowed)
  • wrap keywords in <code>...</code>

typical meta annotations

  • @author is not critical, because it is not included when generating the API specification
  • @version SCCS string "%I%, %G%", which converts to something like “ 1.39, 02/28/97” (mm/dd/yy) when the file is checked out of SCCS
  • @since specify the product version when the Java name was added to the API specification (if different from the implementation)

typical method definition

  • @param parameter-name description
    • followed by the name (not data type) of the parameter, followed by a description of the parameter
    • the first noun in the description is the data type
  • @return description
    • omit for methods that return void and for constructors
    • include it for all other methods, even if its content is entirely redundant with the method description
  • @throws class-name description should be included for any checked exceptions (previously, it was @exception)

additional annotations

  • {@value package.class#field}
    • when {@value} is used (without any argument) in the doc comment of a static field, it displays the value of that constant: The value of this constant is {@value}.
    • otherwise it displays the value of the specified constant: Evaluates the script starting with {@value #SCRIPT_START}.
  • {@code text}
    • Equivalent to <code>{@literal}</code>.

linking

  • @see reference
    • Adds a "See Also" heading
    • reference is a string: Adds a text entry for string. No link is generated. The string is a book or other reference to information not available by URL.
    • reference is an <a href="URL#value">label</a>: Adds a link as defined by URL#value. The URL#value is a relative or absolute URL.
    • reference is an package.class#member label: Adds a link (with optional visible text label) that points to the documentation for the specified name in the Java Language that is referenced.
  • {@link package.class#member label}
    • in-line link with visible text label that points to the documentation for the specified package, class or member name of a referenced class
    • not necessary to add links for all API names in a doc comment
  • @serial (or @serialField or @serialData) for interoperability with alternative implementations of a Serializable class and to document class evolution

deprecation

  • @deprecated deprecated-text
    • the first sentence should at least tell the user when the API was deprecated and what to use as a replacement
    • a {@link} tag should be included that points to the replacement method

example

/**
 * The Class CombineArchive to create/read/manipulate/store etc.
 * CombineArchives.
 * <p>
 * We directly operate on the ZIP file, which will be kept open. Therefore, do
 * not forget to finally close the CombineArchive when you're finished.
 * 
 * @see <a href="https://sems.uni-rostock.de/projects/combinearchive/">
 *      sems.uni-rostock.de/projects/combinearchive</a>
 * @author martin scharm
 */
public class CombineArchive
    extends MetaDataHolder
    implements Closeable
{
    /* ... */

    /**
     * Gets the the first main entry of this archive, if defined. As of RC2 of the spec there may be more than one main entry, so you should use {@link #getMainEntries()} instead.
     * 
     * @return the first main entry, or <code>null</code> if there is no main entry
     * @deprecated as of version 0.8.2, replaced by {@link #getMainEntries()}
     */
    public ArchiveEntry getMainEntry ()
    {
        if (mainEntries == null)
            return null;
        return mainEntries.size () > 0 ? mainEntries.get (0) : null;
    }
    
    /**
     * Gets the main entries as defined in the archive.
     *
     * @return the main entries in this archive
     */
    public List<ArchiveEntry> getMainEntries ()
    {
        return mainEntries;
    }

    /**
     * Replace the file associated with a certain entry while keeping the meta
     * data.
     * 
     * @param toInsert
     *          the new file to insert
     * @param oldEntry
     *          the old entry whose file should be replaced
     * @return the new entry
     * @throws IOException If an input or output exception occurred
     */
    public ArchiveEntry replaceFile (File toInsert, ArchiveEntry oldEntry) throws IOException
    {
        addEntry (toInsert, oldEntry.getFilePath (), oldEntry.getFormat (), false);
        entries.put (oldEntry.getFilePath (), oldEntry);
        return oldEntry;
    }
}

References

Block URLs on phone using AdAway

List of hosts file resources for AdAway
List of hosts file resources for AdAway

Using AdAway on your Android phones it is very easy to block a set of URLs.

AdAway (available from F-Droid, source from GitHub) is an ad-blocker. The application basically maintains a list of resources containing lists to ad-servers, see figure for example, e.g.:

# dest ip   url
127.0.0.1   some.ad.server.com

This entry will redirect all traffic meant for some.ad.server.com to the server 127.0.0.1, which is your localhost. Entries from different resources are merged. Thus, all requests to typical ad-servers will fail → annoying advertisements won’t be delivered. It’s quite powerful and gives impressive results. However, I didn’t want to talk about ad-stuff. The cool thing is

AdAway allows for extensions with own hosts files!

You can simply add another link to a file containing further host entries. I created my own AdAway file, uploaded it to https://stuff.lesscomplex.org/adaway.txt and added it to AdAway, as you can see in the figure. The current version contains a few entries for:

  • facebook/yahoo/etc: I’m not using facebook or stuff, all these request shouldn’t leave my phone
  • captive portal detection: To detect captive portals the phone downloads a few bytes from a google server and checks if it is able to access the real internet or just a captive portal
  • swift key: I’m using swift key, but do not want it to communicate to the internet. Thus, I’m blocking a few URLs that swiftkey wants to talk to. As I’m already using a firewall this just adds another layer of privacy.

Feel free to use my “extension”, but I expect it to change over time. :)

Shortcomings

This method only works if applications load contents from URLs. As soon as the IPs are hard-coded the hosts file

Disable shutter sound on Cyanogenmod 12

Everyone knows that annoying shutter sound of the camera app on Android phones. It’s against the law to sell android phones which do not make sounds when taking pictures. And in general, it is a good feature as it improves other people privacies.

However, I still want to get rid of the sound. It’s a bit tricky, but having a rooted phone (with e.g. CyanogenMod) it’s very easy: Just delete the sound file /system/media/audio/ui/camera_click.ogg! :)

For the lazy: Get a root shell (eg. ssh or adb) and execute the following:

mount -o remount,rw /system
mv /system/media/audio/ui/camera_click.ogg /system/media/audio/ui/camera_click.ogg.backup
mv /system/media/audio/ui/camera_focus.ogg /system/media/audio/ui/camera_focus.ogg.backup
mount -o remount,ro /system

Problem solved.

Kile menu bar hides entries

Figure 1: Kile -- the menu as expected
Figure 1: Kile -- the menu as expected

Kile, KDE’s Integrated LaTeX Environment, has a weird bug: Every time I update something in the UI it recreates its config file and I loose some menu options, such as Settings -> Configure Kile where you used to configure your preferences..

In Figure 1 you can see the menu as expected. There are some entries to Configure Kile, t0 Configure Toolbars, to Configure Shortcuts and to switch to Full Screen Mode, etc. However, as soon as I update certain things in the user interface (UI), eg. if I add a new action icon to the toolbar to quickly get the \textbf{} environment for bold fonts, these entries get lost. In those cases Kile won’t be configureable anymore. The resulting toolbar is shown in Figure 2. You see, the number of entries significantly decreased..

Figure 2: Kile -- the unexpected menu
Figure 2: Kile -- the unexpected menu

However, I just discovered the reason: Kile in these cases rewrites its config in an unexpected manner… If you have a look at the configuration stored in ~/.kde/share/apps/kile/kileui.rc you’ll find an XML subtree such as:

...
<Menu noMerge="1" name="settings">
	<text>&amp;Settings</text>
	<Action name="Mode"/>
	<Separator/>
	<Action name="settings_perform_check"/>
	<Separator/>
	<Action append="show_merge" name="StructureView"/>
	<Action append="show_merge" name="MessageView"/>
</Menu>
...

No idea where it comes from, but the 1 in noMerge prevents the default menu entries to be merged into the minimal set of entries defined in that snippet. However, now that we know what’s wrong we can easily fix it! Just replace the 1 with a 0 and restart Kile. You might want to do the same for all other menus to discover that you’ve also been missing some entries in the Help menu ;-)

Food equivalents in Social Media

I’ve just been listening to a podcast from DRadio Wissen: Hörsaal (German podcast streaming lectures). I particularly like the podcast of DRadio. This time the lecture was held by Fabian Hemmert, a German design researcher, who was talking about the smartphones’ future. Quite interesting thought in there, but what I actually wanted to jot down was his comparison between food and social media. He tried to find food equivalents in media:

The equivalent of Fat is Fiction!

Invented/fictional things – easy to consume, but not a good base. And too much of it and you’ll often have unnecessary ballast at the end of the day.

The equivalent of Sugar is Approbation!

Everyone likes to hear approvals and confirmation, it’s music to your ears. But too much of it is also unhealthy.

The equivalent of Protein is Truth!

Not too easy to digest, but an important thing to base on.

We are very short on Attention

He also notes that attention is the scarcest resource. Everyone wants us to pay attention and we want everyone to pay attention..

I kind of like the idea! Any other equivalences you can think of?



Martin Scharm

stuff. just for the records.

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