Understanding Activities in Android
At this point, since I’ve touched upon Activities in the previous post on Coding Your First Android Application, it seems appropriate to learn a little more about Activities.
Big Picture
The user interface of an application is displayed on a device through an Activity, typically with one Activity created for each unique screen. Internally there is a stack of Activities, when moving from one screen to another, the next Activity to be visible is pushed onto the top of the stack – put another way, the Activity on the top of the stack is what is visible on the display. Activities are popped from the stack by pressing the back button, which resumes the previous Activity.
Continue reading this post »
Coding Your First Android Application
Like most developers, my thought when learning a new platform is “the details can wait.” I’m typically driven to figure out how to get something up and running quickly, diving into the specifics of the APIs, tools and platform once I have something working.
Following that train of thought, the application we’ll create here is nothing more than a simple tableview, with a few rows and columns. However, the process of writing the app will show a number of the basics of building an Android app. It will also give us an opportunity to come back to the code in the next series of post to look further at the some of the details.
Continue reading this post »
Installing Android Development Tools on a Mac
Welcome to inaugural post on Android Developer Tips!
My name is John Muchow, I’ll be your guide as we dive into Android development. I have a long history of writing, evangelizing and blogging about mobile application development. Beyond Android, if you’ve explored iOS programming, you may of bumped into iOSDeveloperTips.com, a popular blog that I started in 2008, that has grown to nearly 200,000 page views per month (as of March 2011).
Not unlike the iOS blog, my focus here will be sharing what I learn in the process of getting up to speed with Android, including the development tools, API’s, devices and a few posts regarding Java, as I’ll need to reacquaint myself with the language (back in 2001 I wrote Core J2ME – now known as Java ME – however, it’s been a number of years since Java has been my focus).
Although this post will reference my installation process using a Mac, I’ll make notes for Windows and Linux as well. For the most part the process is the same, with variations limited to directories and filenames, and of course, the screenshots here being Mac centric.
The Android Development Tools
Here are the tools needed to build Android apps:
• Sun’s Java Development Kit (JDK)
• Android Software Developer Kit (SDK)
• Eclipse IDE
• Android Developer Tool (ADT) Eclipse plug-in
Java Development Kit
The first piece of good news for Mac developers is that Mac OS X has JDK 5 already installed, so we can scratch that off the list.
If you are running Windows or Linux, download and install JDK 5 or 6, you can find the downloads here.
Also worth mentioning before we continue is that Eclipse is not required, however, with the plug-in that Google has developed for Eclipse, they have made the process of editing, compiling, running and debugging quite easy.
Android Software Development Kit
To get things rolling, start by downloading the SDK, choosing the platform you need for your system.
Once you have the zip file downloaded, extract the contents to a folder on your system. In my case, I opted for my home directory in a folder named Android, see the figure below:
In the tools directory, run the application android. From the dialog box that is shown, select Available Packages from the list on the left.
Once you tick the checkbox, a list of sites, packages and archives will appear, choose Install Selected to begin the download process.
Eclipse IDE
It will take a few minutes to download the SDK, so this is a good time to download and install Eclipse. There are a number of Eclipse versions available, my choice was Eclipse IDE for Java Developers, version 3.5 Galileo.
To install Eclipse, unzip the download into a folder. Since Android development is currently my only need for the IDE, I extracted the files into the android folder created previously, in a new folder with the nameeclipse:
Install Android Development Tools (ADT)
All the Android tools should now be downloaded. To install the development tools, start Eclipse – from the eclipse folder (wherever you installed it), double click the application Eclipse. From the Help menu, choose Install New Software.
Enter the path shown in the dialog box below when prompted and then click Add:
From the Add Site dialog, enter the information as shown here and click OK:
You will now be returned to the previous install dialog, go ahead and click the Developer Tools checkbox.
Click Next a few times to get to the license agreement, review the agreements and click Finish to install.
You will get a warning that you are installing unsigned software, select OK to continue:
When prompted, restart Eclipse.
Configure Android Development Kit (ADK) within Eclipse
We now need to setup ADK within Eclipse, which entails pointing Eclipse to the Android SDK.
From with Eclipse, click the Eclipse menu item and choose Preferences. From the list, choose Android, chances are you will see the popup shown below, stating that the SDK has not yet been installed:
Navigate to the folder where Android SDK is installed and click OK:
Update Environment Variables
We can save ourselves some trouble (read frustration) in the future by adding a reference to the Android tools into our path.
In Finder, go to your home directory and open the file .bash_profile – this is a hidden file (hence the preceding dot in the filename).
Add the following line to the file, replacing /Users/JOHN/Android/tools with the proper path to where you installed the Android tools:
# For Android export PATH=${PATH}:/Users/JOHN/Android/tools
Linux: Same as Mac, adding the export to ~/.bash_profile or ~/.bashrc file.
Windows: Right-click on My Computer, and select Properties. On the Advanced tab, click Environment Variables button. A dialog should appear, double-click on Path (under System Variables). Add the full path to the tools directory for Android to the existing path.
And That Does It
At this point we should be good to go. If you run into any issues, or need some help troubleshooting, please refer to the Android Developer site and review Installing the SDK notes.
In the next post I’ll jump into creating an Android application, including how to configure an Android Virtual Device (AVD), which will provide a means to run the app in an emulator.
