<p>Here are some tips and tricks for common Android errors. Don't forget to use the
ddms logcat capability to get a deeper view when errors occur. See <a href="{@docRoot}guide/developing/debug-tasks.html">Debugging</a> for more debugging tips. </p>
<li><a href="#nodevice">ADB reports "no device" when an emulator is running</a></li>
<li><a href="#noapp">My new application/activity isn't showing up in the device application
list </a></li>
<li><a href="#noupdate">I updated my app, but the updates don't seem to be showing up on
the device</a></li>
<li><a href="#layout_wilih">I'm getting a "Binary XML file line #2: You must supply a layout_wilih
attribute" error when I start an application</a></li>
<li><a href="#permission">My request to (<em>make a call, catch an incoming SMS, receive
a notification, send an intent to an Android application</em>) is being
ignored</a></li>
<li><a href="#build">Help! My project won't build in Eclipse</a></li>
<li><a href="#eclipse">Eclipse isn't talking to the emulator</a></li>
<li><a href="#majorminor">When I go to preferences in Eclipse and select "Android", I get the following error message: Unsupported major.minor version 49.0.</a></li>
<li><a href="#apidemosreinstall">I can't install ApiDemos apps in my IDE because of a signing error</a></li>
<li>If logcat shows that the package manager is having problems loading the manifest
file, force your manifest to be recompiled by adding a space in the file and
compiling it.</li>
</ul>
<a name="noupdate"></a><h2>I updated my app, but the updates don't seem to be showing up on the device</h2>
<p>Did you remember to send your .apk file to the device (<a href="{@docRoot}guide/developing/tools/adb.html#move">adb
install</a>)?</p>
<a name="layout_wilih"></a><h2>I'm getting a "Binary XML file line #2: You must supply a layout_wilih
attribute" error
when I start an application (but I declare a layout_wilih attribute <em>right
there!!!</em>)</h2>
<ul>
<li>Make sure that the SDK you are building with is the same version as the Android
OS that you are running on. </li>
<li>Make sure that you're calling setContentView() early in your onCreate() method.
Calling other methods, such as setListAdapter() before calling setContentView()
can sometimes create odd errors when Android tries to access screen elements
that haven't been set before.</li>
</ul>
<a name="permission"></a><h2>My request to (<em>make a call, catch an incoming SMS,
receive a notification, send an intent to an Android application</em>) is being
ignored</h2>
<p>You might not have permission (or might not have requested permission) to
call this activity or receive this intent. Many standard Android activities,
such as making a call, have a permission assigned to it to prevent arbitrary
applications from sending or receiving requests. See <a
href="{@docRoot}guide/topics/security/security.html">Security and
Permissions</a> for more information on permissions, and
{@link android.Manifest.permission Manifest.permission} for a list of
standard permissions supported by the Android platform.
</p>
<a name="build"></a><h2>Help! My project won't build in Eclipse</h2>
<p>If your project doesn't build, you may notice symptoms such as new
resources added in the <code>res/</code> sub-folders not showing up in the R class,
the emulator not being started, not being able to run the application, or even seeming to run an old version of the application.</p>
<p>To troubleshoot these types of problems, first try:</p>
<ol>
<li>Switch to the DDMS view in Eclipse (if you don't already have it open):
<ol type="a">
<li>From the menu select <code>Window > Open Perspective > Other</code></li>
<li>Select DDMS from the list and hit OK</li>
</ol>
</li>
<li>In the Devices panel (top right panel by default), click on the down triangle
to bring up the panel menu</li>
<li>Select <code>Reset ADB</code> from the menu, and then try running the
application again</li>
</ol>
<p>If the above still doesn't work, you can try these steps:</p>
<ol>
<li>
Check the console and problems tabs at the bottom of the Eclipse UI
</li>
<li>
If there are problems listed in either place, they should give you a clue
what is wrong
</li>
<li>
If you aren't sure if the problems are fresh or stale, clear the console
with a right click > Clear, then clean the project
</li>
<li>
To clean the project (a good idea with any kind of build error), select
Project > Clean from the eclipse main menu, then select the project you
are working on (or clean all)
</li>
</ol>
<a name="eclipse"></a><h2>Eclipse isn't talking to the emulator</h2>
<p>When communication doesn't seem to be happening between Eclipse and the emulator, symptoms can include: nothing happening when you press run, the emulator hanging waiting
for a debugger to connect, or errors that Eclipse reports about not being able
to find the emulator or shell. By far the most common symptom is that when you press run, the emulator starts (or
is already running), but the application doesn't start.</p>
<p>
You may find any of these steps will fix the problem and with practice you
probably can figure out which one you need to do for your particular issue, but
to start with, the safest option is to run through all of them in order:</p>
<ol>
<li>
Quit the emulator if it is running
</li>
<li>
Check that any emulator processes are killed (sometimes they can hang, use ps on unix or mac, or task manager in the process view on
windows).
</li>
<li>
Quit Eclipse
</li>
<li>
From the command line, type:
<pre>adb kill-server </pre>
</li>
<li>
Start Eclipse and try again
</li>
</ol>
<a name="majorminor"></a><h2>When I go to preferences in Eclipse and select "Android", I get the following error message: Unsupported major.minor version 49.0.</h2>
<p>This error is displayed if you are using an older version of the JDK. Please make sure you are using JDK version 5 or 6.</p>
<h2 id="apidemosreinstall">I can't install ApiDemos apps in my IDE because of a signing error</a></h2>
<p>The Android system requires that all applications be signed, as described in
<a href="{@docRoot}guide/publishing/app-signing.html">Signing Your Applications</a>. The ApiDemos
applications included with the SDK are preinstalled on the emulator and for that reason have been
compiled and signed with a private key.</p>
If you want to modify or run one of the ApiDemos apps from Eclipse/ADT or other IDE, you can do so
so only after you uninstall the <em>preinstalled</em> version of the app from the emulator. If
you try to run an ApiDemos apps from your IDE without removing the preinstalled version first,
you will get errors similar to: </p>
<pre>[2008-08-13 15:14:15 - ApiDemos] Re-installation failed due to different application signatures.
[2008-08-13 15:14:15 - ApiDemos] You must perform a full uninstall of the application. WARNING: ...This will remove the application data!
[2008-08-13 15:14:15 - ApiDemos] Please execute 'adb uninstall com.android.samples' in a shell.</pre>
<p>The error occurs because, in this case, you are attempting to install another copy of ApiDemos
onto the emulator, a copy that is signed with a different certificate (the Android IDE tools will
have signed the app with a debug certificate, where the existing version was already signed with
a private certificate). The system does not allow this type of reinstallation. </p>
<p>To resolve the issue, you need to fully uninstall the preinstalled and then reinstall it using
the adb tool. Here's how to do that:</p>
<ol>
<li>In a terminal, change to the tools directory of the SDK.</li>
<li>If no emulator instance is running, start an emulator using using the command <code>emulator &</code>.</li>
<li>Uninstall the preinstalled app using the command <code>adb uninstall com.android.samples</code>.</li>
<li>Reinstall the app using the command <code>adb install <path to the ApiDemos.apk></code>. If you are
working in Eclipse/ADT, you can just compile and run the app in the normal way. </li>
</ol>
<p>Note that if multiple emulator instances are running, you need to direct your uninstall/install
commands to the emulator instance that you are targeting. To do that you can add the
<code>-s <serialNumber></code> to the command, for example: </p>
<pre>adb -s emulator-5556 install</pre>
<p>For more information about adb, see the <a href="{@docRoot}guide/developing/tools/adb.html">Android Debug Bridge</a>
<h2 id="signingcalendar">I can't compile my app because the build tools generated an expired debug certificate</h2>
<p>If your development machine uses a locale that has a non-Gregorian calendar, you may encounter problems when first trying to compile and run your application. Specifically, you may find that the Android build tools won't compile your application because the debug key is expired. </p>
<p>The problem occurs because the Keytool utility — included in the JDK and used by the Android build tools — fails to properly handle non-Gregorian locales and may create validity dates that are in the past. That is, it may generate a debug key that is already expired, which results in the compile error.</p>
<p>If you encounter this problem, follow these steps to work around it: </p>
<ol>
<li>First, delete the debug keystore/key already generated by the Android build tools. Specifically, delete the <code>debug.keystore</code> file. On Linux/Mac OSX, the file is stored in <code>~/.android</code>. On Windows XP, the file is stored in <code>
C:\Documents and Settings\<user>\.android</code>. On Windows Vista, the file is stored in <code>
C:\Users\<user>\.android</code></li>
<li>Next, you can either
<ul>
<li>Temporarily change your development machine's locale (date and time) to one that uses a Gregorian calendar, for example, United States. Once the locale is changed, use the Android build tools to compile and install your app. The build tools will regenerate a new keystore and debug key with valid dates. Once the new debug key is generated, you can reset your development machine to the original locale. </li>
<li>Alternatively, if you do not want to change your machine's locale settings, you can generate the keystore/key on any machine using the Gregorian calendar, then copy the <code>debug.keystore</code> file from that computer to the proper location on your development machine. </li>
</ul>
</li>
</ol>
<p>This problem has been verified on Windows and may apply to other platforms. </p>
<p>For general information about signing Android applications, see
<a href="{@docRoot}guide/publishing/app-signing.html">Signing Your Applications</a>. </p>
