Building Your Application

There are two ways to build your application: one for testing/debugging your application — debug mode — and one for building your final package for release — release mode. As described in the previous section, your application must be signed before it can be installed on an emulator or device.

Whether you're building in debug mode or release mode, you need to use the Ant tool to compile and build your project. This will create the .apk file that is installed onto the emulator or device. When you build in debug mode, the .apk file is automatically signed by the SDK tools with a debug key, so it's instantly ready for installation (but only onto an emulator or attached development device). When you build in release mode, the .apk file is unsigned, so you must manually sign it with your own private key, using Keytool and Jarsigner.

It's important that you read and understand Signing Your Applications, particularly once you're ready to release your application and share it with end-users. That document describes the procedure for generating a private key and then using it to sign your .apk file. If you're just getting started, however, you can quickly run your applications on an emulator or your own development device by building in debug mode.

If you don't have Ant, you can obtain it from the Apache Ant home page. Install it and make sure it is in your executable PATH. Before calling Ant, you need to declare the JAVA_HOME environment variable to specify the path to where the JDK is installed.

Note: When installing JDK on Windows, the default is to install in the "Program Files" directory. This location will cause ant to fail, because of the space. To fix the problem, you can specify the JAVA_HOME variable like this: set JAVA_HOME=c:\Prora~1\Java\. The easiest solution, however, is to install JDK in a non-space directory, for example: c:\java\jdk1.6.0_02.

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