78 lines
3.6 KiB
Plaintext
78 lines
3.6 KiB
Plaintext
page.title=Using the Dev Tools App
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parent.title=Debugging
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parent.link=index.html
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@jd:body
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<p>The Dev Tools application is installed by default on all system images included with the SDK,
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so you can use it with the Android Emulator. With the Dev Tools application, you can enable a
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number of settings on your device that will make it easier to test and debug your applications.</p>
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<p> The Dev Tools application relies on a number of permissions that are not available for
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third party applications. If you'd like to install the Dev Tools application
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on a real development device, you'd have to build a system image for that device and sign
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the Dev Tools application with the same key as used for the system image.</p>
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<p>To get started, launch the Dev Tools application and select <strong>Development Settings</strong>. This will
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open the Development Settings page with the following options (among others):</p>
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<dl>
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<dt><strong>Debug app</strong></dt>
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<dd>
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Lets you select the application to debug. You do not need to set this to attach a debugger,
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but setting this value has two effects:
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<ul>
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<li>It will prevent Android from throwing an error if you pause on a breakpoint for a long
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time while debugging.</li>
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<li>It will enable you to select the <em>Wait for Debugger</em> option to pause application
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startup until your debugger attaches (described next).</li>
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</ul>
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</dd>
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<dt><strong>Wait for debugger</strong></dt>
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<dd>Blocks the selected application from loading until a debugger attaches. This way you can
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set a breakpoint in {@link android.app.Activity#onCreate onCreate()},
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which is important to debug the startup process of an Activity.
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When you change this option, any currently running instances of the selected application will
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be killed. In order to check this box, you must have selected a debug application as described
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in the previous option. You can do the same thing by adding {@link
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android.os.Debug#waitForDebugger()} to your code.</dd>
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<dt><strong>Show screen updates</strong></dt>
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<dd>Flashes a momentary pink rectangle on any screen sections that are being redrawn. This is
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very useful for discovering unnecessary screen drawing.</dd>
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<dt><strong>Immediately destroy activities</strong></dt>
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<dd>Tells the system to destroy an activity as soon as it is stopped (as if Android had to
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reclaim memory). This is very useful for testing the {@link
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android.app.Activity#onSaveInstanceState} / {@link
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android.app.Activity#onCreate(android.os.Bundle)} code path, which would otherwise be difficult
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to force. Choosing this option will probably reveal a number of problems in your application
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due to not saving state. For more information about saving an activity's state, see the
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<a href="{@docRoot}guide/components/activities.html#SavingActivityState">Activities</a>
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document.</dd>
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<dt><strong>Show CPU usage</strong></dt>
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<dd>Displays CPU meters at the top of the screen, showing how much the CPU is being used. The
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top red bar shows overall CPU usage, and the green bar underneath it shows the CPU time spent
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in compositing the screen.
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<p class="note">Note: You cannot turn this feature off once it is on, without
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restarting the emulator.</p></dd>
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<dt><strong>Show background</strong></dt>
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<dd>Displays a background pattern when no activity screens are visible. This typically does not
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happen, but can happen during debugging.</dd>
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</dl>
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<p>These settings will be remembered across emulator restarts.</p>
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