Take the activity lifecycle for example. Under normal circumstances activities are only destroyed when their finish() method is called or the system needs to free up some memory. From a testing perspective this isn’t very deterministic so testing what happens when activities are destroyed is either forgotten about or not given the attention it deserves.

Luckily there are tools to help in these scenarios. The Dev Tools App is particularly useful. It’s automatically installed with every virtual device created using the Android Virtual Device Manager in Eclipse.

Testing Activity Destruction

To test what happens to your app when activities are destroyed tick the Immediately destroy activities checkbox under Development Settings in Dev Tools. This instructs Android to immediately destroy activities that are no longer visible. Under normal conditions you might never get to this test scenario if you don’t explicitly call finish() on your activities. It’s amazing the subtle bugs this can throw up.

Testing Process Termination

Another very useful test is to see what happens when your application’s process is terminated. When I stated out with UPM I received quite a number of crash reports that initially baffled me. The stack traces suggested situations that I just couldn’t recreate. It wasn’t until I started thinking about the impact of process termination that I found the root of the problems.

When a terminated application is restarted Android will try and return the user to whatever activity was previously in the foreground. This can cause problems if the activity assumes too much about the application’s state, e.g. what static variables are initialized. Restarting the application means there’s a new process so the static state of the previous instance is gone. Here’s how I test this scenario.

First I start the application in an emulator as normal. Once I’ve made it to the activity under test I hit the Home button to send the application into the background. Now I need to kill the application’s process. There’s a few ways to do this. My favourite is to use adb. adb is located in the Android SDK platform-tools directory. Running

$ adb shell

starts a shell on the emulator. From there I use

$ ps

to find the application’s process and

$ kill -9 <pid>

to kill the process. Once I’ve killed the process I go back to the emulator and hit the application’s icon to restart it. Android will try to resume the activity that was previously in the foreground. Ideally there should be no problems but if there are they’ll usually present themselves as a NullPointerException with a “Force Close” dialog for the user.

Android can be a difficult, confusing platform to work with. This is particularly true if you’re coming from a regular desktop application environment. There’s a paradigm shift in thinking required to fully appreciate the transient nature of the Android environment. Thankfully, once you’ve made that leap things do get easier. The most useful resources I’ve found are the Android Developer’s Guide and Stackoverflow.

The PRTB publish a list of all registered rental properties in Ireland on their website. The data is split up into 47 separate spreadsheets (xls), one for each county and Dublin postcode. There’s a lot of interesting information in there but it’s very difficult to get at it when it’s in so many files. For this reason I’ve loaded all the information into a database.

Before looking at the data it’s worth bearing a few things in mind,

• the data is effective 1-Apr-2011
• there are a lot of properties included in “County Dublin” that are really part of an area code. this has the effect of bumping up the number of properties in “County Dublin”
• some properties appear to have their floorspace given in square meters while others have it in square feet. this makes it difficult to do a consistent analysis of the full dataset
• there seems to be a few properties with duplicate entries

I’ve included some high level numbers below. If you’d like to have a look at the data yourself I’ve published it in searchable form here. The code for this application is available on my GitHub page.

Total number of properties: 221,315

Number of properties per county:

Number of properties per Dublin area code:

This script will decorate product pages on amazon.co.uk with the equivilent irish price. This price will be in euro and include the irish VAT rate where applicable.

Firefox GreaseMonkey Script: Install, Source Code

Chrome Extension: Install, Source Code

Universal Password Manager has been hosted on SourceForge since it’s launch in December 2005. Over the course of those years there have been many patches offered by generous developers looking to help improve it. While merging these patches is usually straight forward I can imagine how difficult it would be if the project was very popular and had tens or even hundreds of contributors.

GitHub offers a very attractive alternative. Each contributor can clone the repository, make their changes and then send you a pull request. As the project maintainer your job is now a whole lot easier and more manageable. No more patch files to worry about. Everything is organised and fully traceable.

For this reason (and so that I can use and learn more about Git) I decided to move UPM’s code from SourceForge to GitHub. These instructions are nothing new. There are plenty of similar posts. What I’m offering here are the steps I went through from start to finish.

1. Install svn2git. This involves installing git, ruby and ruby gems. Full instructions are available here.

2. Create a link to svn2git

$ sudo ln -s /var/lib/gems/1.8/bin/svn2git /usr/bin/svn2git

3. Copy down your project’s subversion repository to help speed up the migration process. SourceForge make this very easy by providing an rsync daemon. See here for details.

$ rsync -av upm.svn.sourceforge.net::svn/upm/* .

4. Create an authors file. This is used to map the authors in your Subversion repository to those you want to use in Git.

adrian = Adrian Smith <adrian@email.com>

5. Create a new Git repository for your project. This will be a local repository for now so there’s no need to worry about GitHub just yet.

$ mkdir my_project
$ cd my_project
$ git init

6. Run svn2git. This process can take a while (hours if your repository is exceptionally large). What it’s doing is reading each Subversion revision and creating a corresponding Git commit.

$ svn2git file:///home/adrian/upm.sourceforge/ --trunk swing/trunk --branches swing/branches --tags swing/tags --authors ../upm-authors

7. If you want to check that you new repository has the same number of commits as your old Subversion repository you can do something like this…

$ svn log -q | grep '^r[0-9]' | wc -l (count subversion revisions)
$ git log --oneline | wc -l (count git commits)

8. Create your new GitHub repository as described on this page following the Existing Repo? instructions.

Since we’ve gone to all this trouble we might as well leave a little message on SourceForge redirecting visitors interested in the source code to the new GitHub page.

1. Logon to SourceForge and go to Project Admin -> Feature Settings.

2. Select Manage next to Subversion and go to Non-SF.net Resource (Active). This page allows you to leave a short message and a link to the new project page. It’s unfortunate there’s so much talk about Subverison on this page but the Git feature doesn’t have the option of redirecting visitors to an external host.

That should be it. Have fun.

From the release notes…

• Long-clicking on an account now brings up a context menu allowing you to copy username, copy password, launch URL or edit account
• Added the ability to trust self signed certificates and certificates that have a different Common Name to the website hostname
• Increased the font size on the Account Details activity
• Fixed a bug on the main Accounts page so that it recovers gracefully when the database is closed unexpectedly

On the client side I used the YUI Javascript framework and JSON as the data interchange format. There didn’t seem to be a direct example of doing this on the Recess website here’s what I came up with.

The only Recess specific requirement is that the Json View is registered on your application controller. More info on views here.

!RespondsWith Layouts, Json

Here’s Javascript code to create a object of type Entry. The object has two attributes, “date” and “data”.

Y.io("/recess/myjournal/entry/", {
  method: "POST",
  data: {
    "entry[date][day]": Y.one("#entryDay").get("value"),
    "entry[date][month]": Y.one("#entryMonth").get("value"),
    "entry[date][year]": Y.one("#entryYear").get("value"),
    "entry[data]": Y.one("#entryText").get("value")
  },
  on: {
    success: function(transactionid, response, arguments) {
      alert("entry successfully added");
    },
    failure: function(transactionid, response, arguments) {
      alert("add entry failed: " + response.responseText);
    }
  }
});

For anyone interested in seeing this code in context here’s the page it’s used on. Remember this is just some simple proof of concept stuff so it’s very rough and ready.

<html>
  <head>
    <title>My Journal</title>
    <script type="text/javascript" charset="utf-8" src="http://yui.yahooapis.com/3.1.1/build/yui/yui-min.js"></script>
  </head>
  <body>
    <h2>Entries</h2>
    <ul id="entriesList">
    </ul>

    <form id="newEntryForm" style="display: none">
      <input id="entryDay" type="text" size="2" maxlength="2">
      <select id="entryMonth">
        <option value="1">Jan</option>
        <option value="2">Feb</option>
        <option value="3">Mar</option>
        <option value="4">Apr</option>
        <option value="5">May</option>
        <option value="6">June</option>
        <option value="7">July</option>
        <option value="8">Aug</option>
        <option value="9">Sept</option>
        <option value="10">Oct</option>
        <option value="11">Nov</option>
        <option value="12">Dec</option>
      </select>
      <input id="entryYear" type="text" size="2" maxlength="4">
      <br />
      <textarea id="entryText" rows="10" cols="20"></textarea>
      <br />
      <input id="cancelAddButton" type="button" value="Cancel">
      <input id="saveEntryButton" type="button" value="Save">
    </form>

    <form>
      <input id="refreshButton" type="button" value="Refresh" disabled="true">
      <input id="addButton" type="button" value="Add">
    </form>

    <script>
      YUI().use("node", "io", "json", "datatype-date", "querystring-stringify-simple", function(Y) {
        // Add an entry to list
        var addEntryToList = function(entryDate) {
          var listNode = Y.one("#entriesList");
          var date = Y.DataType.Date.format(entryDate, {format: "%Y-%m-%d"});
          listNode.append("<li>" + date + "</li>");
        };

        // Retrieve entries and add them to the list
        var populateEntriesList = function() {
          Y.one("#refreshButton").set("disabled", true);

          Y.io("/recess/myjournal/entry.json", {
            method: "GET",
            on: {
              success: function(transactionid, response, arguments) {
                var listNode = Y.one("#entriesList");
                listNode.get("children").remove();

                var entries = Y.JSON.parse(response.responseText);

                Y.each(entries.entrySet, function(entry, index, array) {
                  // The date coming from the server will by in seconds. Date() expects milliseconds so * by 1000.
                  addEntryToList(new Date(entry.date * 1000));
                });
              },
              failure: function(transactionid, response, arguments) {
                alert("get entries failed: " + response.responseText);
              },
              end: function(transactionid, arguments) {
                Y.one("#refreshButton").set("disabled", false);
              }
            }
          });
        };

        var showAddEntryControls = function() {
          Y.one("#newEntryForm").setStyle("display", "block");
        };

        var saveEntry = function() {
          Y.io("/recess/myjournal/entry/", {
            method: "POST",
            data: {
              "entry[date][day]": Y.one("#entryDay").get("value"),
              "entry[date][month]": Y.one("#entryMonth").get("value"),
              "entry[date][year]": Y.one("#entryYear").get("value"),
              "entry[data]": Y.one("#entryText").get("value")
            },
            on: {
              success: function(transactionid, response, arguments) {
                var entryDate = new Date(
                  Y.one("#entryYear").get("value"),
                  Y.one("#entryMonth").get("value") - 1,
                  Y.one("#entryDay").get("value")
                );
                addEntryToList(entryDate);
              },
              failure: function(transactionid, response, arguments) {
                alert("add entry failed: " + response.responseText);
              },
              end: function(transactionid, arguments) {
                Y.one("#newEntryForm").setStyle("display", "none");
              }
            }
          });
        };

        var cancelAddEntry = function() {
          Y.one("#newEntryForm").setStyle("display", "none");
        };

        Y.on("available", populateEntriesList, "#entriesList");
        Y.one("#refreshButton").on("click", populateEntriesList);
        Y.one("#addButton").on("click", showAddEntryControls);
        Y.one("#cancelAddButton").on("click", cancelAddEntry);
        Y.one("#saveEntryButton").on("click", saveEntry);
      });
    </script>
  </body>
</html>

What this plugin does is update each product page with the equivalent Euro price. The GBP to EUR rate is retrieved in real time from Yahoo Finance. The Irish VAT rate of 21% is included except on books which are exempt from VAT.

Now available on Chrome.

The original Firefox version is still available here.

From the release notes…

• Added the ability to export/import from/to a CSV file
• Added a random password generator
• Removed the dependency on JCE Unlimited Strength Jurisdiction Policy Files
• Added support for using HTTPS URLs with database sharing
• Set focus on the password field on all enter master password dialogs
• Added Spanish translation (courtesy of Victor Alfonso Pineda)
• Resize the “Notes” text area when the Account Details dialog is resized

• Shared Database support
• Delete Database support
• Lots of bugs fixes and improvements

The shared database feature was the primary focus of 1.1. With this it’s now possible to sync your password database with the desktop version. For full details on how to setup and use database sharing see the user guide.

You can upgrade from the Android Marketplace or download the APK directly from Sourceforge.

If you have any problems post please use the Help Forum.

UPDATE: When you upgrade you may get an error telling you UPM is no longer available when you try to start it. To fix this you should restart your phone and recreate any shortcut you have to UPM on your Home screen.

For those who are interested this seems to be a problem with Android 1.5 and how it handles a change to the main Activity after an upgrade. If you have any experience or details on this problem I’d be interested hear about it.

Oracle DBMS_CHANGE_NOTIFICATION
An interesting way of subscribing to events in an Oracle db. Could be used as an alternative to triggers where the work to be carried out is not possible from a trigger or needs to be done async to the trigger.

QuickSharp
MonoDevelop
SharpDevelop IDE for C#
A few opensource C# IDEs.