Android Emulator Keyboard Commands

Table 1 summarizes the mappings between the emulator keys and the keys of your keyboard.

Table 1. Emulator keyboard mapping

Emulated Device Key	Keyboard Key
Home	HOME
Menu (left softkey)	F2 or Page-up button
Star (right softkey)	Shift-F2 or Page Down
Back	ESC
Call/dial button	F3
Hangup/end call button	F4
Search	F5
Power button	F7
Audio volume up button	KEYPAD_PLUS, Ctrl-F5
Audio volume down button	KEYPAD_MINUS, Ctrl-F6
Camera button	Ctrl-KEYPAD_5, Ctrl-F3
Switch to previous layout orientation (for example, portrait, landscape)	KEYPAD_7, Ctrl-F11
Switch to next layout orientation (for example, portrait, landscape)	KEYPAD_9, Ctrl-F12
Toggle cell networking on/off	F8
Toggle code profiling	F9 (only with `-trace` startup option)
Toggle fullscreen mode	Alt-Enter
Toggle trackball mode	F6
Enter trackball mode temporarily (while key is pressed)	Delete
DPad left/up/right/down	KEYPAD_4/8/6/2
DPad center click	KEYPAD_5
Onion alpha increase/decrease	KEYPAD_MULTIPLY(*) / KEYPAD_DIVIDE(/)

Command Line Parameters

The emulator supports a variety of options that you can specify when launching the emulator, to control its appearance or behavior. Here's the command-line syntax of the options available to the emulator program:

emulator -avd <avd_name> [-<option> [<value>]] ... [-<qemu args>]

Table 2. Emulator command line parameters

Category	Option	Description	Comments
AVD	`-avd <avd_name>` or `@<avd_name>`	Required. Specifies the AVD to load for this emulator instance.	You must create an AVD configuration before launching the emulator. For information, see Managing AVDs with AVD Manager.
Disk Images	`-cache <filepath>`	Use <filepath> as the working cache partition image.	An absolute or relative path to the current working directory. If no cache file is specified, the emulator's default behavior is to use a temporary file instead. For more information on disk images, use `-help-disk-images`.
	`-data <filepath>`	Use `<filepath>` as the working user-data disk image.	Optionally, you can specify a path relative to the current working directory. If `-data` is not used, the emulator looks for a file named `userdata-qemu.img` in the storage area of the AVD being used (see `-avd`).
	`-initdata <filepath>`	When resetting the user-data image (through `-wipe-data`), copy the contents of this file to the new user-data disk image. By default, the emulator copies the `<system>/userdata.img`.	Optionally, you can specify a path relative to the current working directory. See also `-wipe-data`. For more information on disk images, use `-help-disk-images`.
	`-nocache`	Start the emulator without a cache partition.	See also `-cache <file>`.
	`-ramdisk <filepath>`	Use <filepath> as the ramdisk image.	Default value is `<system>/ramdisk.img`. Optionally, you can specify a path relative to the current working directory. For more information on disk images, use `-help-disk-images`.
	`-sdcard <filepath>`	Use <file> as the SD card image.	Default value is `<system>/sdcard.img`. Optionally, you can specify a path relative to the current working directory. For more information on disk images, use `-help-disk-images`.
	`-wipe-data`	Reset the current user-data disk image (that is, the file specified by `-datadir` and `-data`, or the default file). The emulator deletes all data from the user data image file, then copies the contents of the file at `-inidata` data to the image file before starting.	See also `-initdata`. For more information on disk images, use `-help-disk-images`.
Debug	`-debug <tags>`	Enable/disable debug messages for the specified debug tags.	`<tags>` is a space/comma/column-separated list of debug component names. Use `-help-debug-tags` to print a list of debug component names that you can use.
	`-debug-<tag>`	Enable/disable debug messages for the specified debug tag.	Use `-help-debug-tags` to print a list of debug component names that you can use in `<tag>`.
	`-debug-no-<tag>`	Disable debug messages for the specified debug tag.
	`-logcat <logtags>`	Enable logcat output with given tags.	If the environment variable ANDROID_LOG_TAGS is defined and not empty, its value will be used to enable logcat output by default.
	`-shell`	Create a root shell console on the current terminal.	You can use this command even if the adb daemon in the emulated system is broken. Pressing Ctrl-c from the shell stops the emulator instead of the shell.
	`-shell-serial <device>`	Enable the root shell (as in `-shell` and specify the QEMU character device to use for communication with the shell.	<device> must be a QEMU device type. See the documentation for '-serial dev' at http://wiki.qemu.org/download/qemu-doc.html for a list of device types. Here are some examples: `-shell-serial stdio` is identical to `-shell` `-shell-serial tcp::4444,server,nowait` lets you communicate with the shell over TCP port 4444 `-shell-serial fdpair:3:6` lets a parent process communicate with the shell using fds 3 (in) and 6 (out) `-shell-serial fdpair:0:1` uses the normal stdin and stdout fds, except that QEMU won't tty-cook the data.
	`-show-kernel <name>`	Display kernel messages.
	`-trace <name>`	Enable code profiling (press F9 to start), written to a specified file.
	`-verbose`	Enable verbose output.	Equivalent to `-debug-init`. You can define the default verbose output options used by emulator instances in the Android environment variable ANDROID_VERBOSE. Define the options you want to use in a comma-delimited list, specifying only the stem of each option: `-debug-<tags>.` Here's an example showing ANDROID_VERBOSE defined with the `-debug-init` and `-debug-modem` options: `ANDROID_VERBOSE=init,modem` For more information about debug tags, use `<-help-debug-tags>`.
Media	`-audio <backend>`	Use the specified audio backend.
	`-audio-in <backend>`	Use the specified audio-input backend.
	`-audio-out <backend>`	Use the specified audio-output backend.
	`-noaudio`	Disable audio support in the current emulator instance.
	`-radio <device>`	Redirect radio modem interface to a host character device.
	`-useaudio`	Enable audio support in the current emulator instance.	Enabled by default.
Network	`-dns-server <servers>`	Use the specified DNS server(s).	The value of `<servers>` must be a comma-separated list of up to 4 DNS server names or IP addresses.
	`-http-proxy <proxy>`	Make all TCP connections through a specified HTTP/HTTPS proxy	The value of `<proxy>` can be one of the following: `http://<server>:<port>` `http://<username>:<password>@<server>:<port>` The `http://` prefix can be omitted. If the `-http-proxy <proxy>` command is not supplied, the emulator looks up the `http_proxy` environment variable and automatically uses any value matching the `<proxy>` format described above.
	`-netdelay <delay>`	Set network latency emulation to <delay>.	Default value is `none`. See the table in Network Delay Emulation for supported `<delay>` values.
	`-netfast`	Shortcut for `-netspeed full -netdelay none`
	`-netspeed <speed>`	Set network speed emulation to <speed>.	Default value is `full`. See the table in Network Speed Emulation for supported `<speed>` values.
	`-port <port>`	Set the console port number for this emulator instance to `<port>`.	The console port number must be an even integer between 5554 and 5584, inclusive. `<port>`+1 must also be free and will be reserved for ADB.
	`-report-console <socket>`	Report the assigned console port for this emulator instance to a remote third party before starting the emulation.	`<socket>` must use one of these formats: `tcp:<port>[,server][,max=<seconds>]` `unix:<port>[,server][,max=<seconds>]` Use `-help-report-console` to view more information about this topic.
System	`-cpu-delay <delay>`	Slow down emulated CPU speed by <delay>	Supported values for <delay> are integers between 0 and 1000. Note that the <delay> does not correlate to clock speed or other absolute metrics — it simply represents an abstract, relative delay factor applied non-deterministically in the emulator. Effective performance does not always scale in direct relationship with <delay> values.
	`-gps <device>`	Redirect NMEA GPS to character device.	Use this command to emulate an NMEA-compatible GPS unit connected to an external character device or socket. The format of `<device>` must be QEMU-specific serial device specification. See the documentation for 'serial -dev' at http://wiki.qemu.org/download/qemu-doc.html.
	`-nojni`	Disable JNI checks in the Dalvik runtime.
	`-qemu`	Pass arguments to the qemu emulator software.	Important: When using this option, make sure it is the last option specified, since all options after it are interpretted as qemu-specific options.
	`-qemu -enable-kvm`	Enable KVM acceleration of the emulator virtual machine.	This option is only effective when your system is set up to use KVM-based VM acceleration. You can optionally specify a memory size (`-m <size>`) for the VM, which should match your emulator's memory size: `-qemu -m 512 -enable-kvm` `-qemu -m 1024 -enable-kvm`
	`-qemu -h`	Display qemu help.
	`-gpu on`	Turn on graphics acceleration for the emulator.	This option is only available for emulators using a system image with API Level 15, revision 3 and higher. For more information, see Using the Android Emulator.
	`-radio <device>`	Redirect radio mode to the specified character device.	The format of `<device>` must be QEMU-specific serial device specification. See the documentation for 'serial -dev' at http://wiki.qemu.org/download/qemu-doc.html.
	`-timezone <timezone>`	Set the timezone for the emulated device to <timezone>, instead of the host's timezone.	`<timezone>` must be specified in zoneinfo format. For example: "America/Los_Angeles" "Europe/Paris"
	`-version`	Display the emulator's version number.
UI	`-dpi-device <dpi>`	Scale the resolution of the emulator to match the screen size of a physical device.	The default value is 165. See also `-scale`.
	`-no-boot-anim`	Disable the boot animation during emulator startup.	Disabling the boot animation can speed the startup time for the emulator.
	`-no-window`	Disable the emulator's graphical window display.
	`-scale <scale>`	Scale the emulator window.	`<scale>` is a number between 0.1 and 3 that represents the desired scaling factor. You can also specify scale as a DPI value if you add the suffix "dpi" to the scale value. A value of "auto" tells the emulator to select the best window size.
	`-raw-keys`	Disable Unicode keyboard reverse-mapping.
	`-noskin`	Don't use any emulator skin.
	`-keyset <file>`	Use the specified keyset file instead of the default.	The keyset file defines the list of key bindings between the emulator and the host keyboard. For more information, use `-help-keyset` to print information about this topic.
	`-onion <image>`	Use overlay image over screen.	No support for JPEG. Only PNG is supported.
	`-onion-alpha <percent>`	Specify onion skin translucency value (as percent).	Default is 50.
	`-onion-rotation <position>`	Specify onion skin rotation.	`<position>` must be one of the values 0, 1, 2, 3.
	`-skin <skinID>`	This emulator option is deprecated.	Please set skin options using AVDs, rather than by using this emulator option. Using this option may yield unexpected and in some cases misleading results, since the density with which to render the skin may not be defined. AVDs let you associate each skin with a default density and override the default as needed. For more information, see Managing Virtual Devices with AVD Manager.
	`-skindir <dir>`	This emulator option is deprecated.	See comments for `-skin`, above.
Help	`-help`	Print a list of all emulator options.
	`-help-all`	Print help for all startup options.
	`-help-<option>`	Print help for a specific startup option.
	`-help-debug-tags`	Print a list of all tags for `-debug <tags>`.
	`-help-disk-images`	Print help for using emulator disk images.
	`-help-environment`	Print help for emulator environment variables.
	`-help-keys`	Print the current mapping of keys.
	`-help-keyset-file`	Print help for defining a custom key mappings file.
	`-help-virtual-device`	Print help for Android Virtual Device usage.

Differences between the px, dip, dp and sp units in Android

4:24 AM C4KTeam 1 comment

A dimension value defined in XML. A dimension is specified with a number followed by a unit of measure. For example: 10px, 2in, 5sp. The following units of measure are supported by Android:

px is one pixel. scale-independent pixels ( sp ) and density-independent pixels ( dip ) you want to use sp for font sizes and dip for everything else.

dp: Density-independent Pixels - An abstract unit that is based on the physical density of the screen. These units are relative to a 160 dpi (dots per inch) screen, on which 1dp is roughly equal to 1px. When running on a higher density screen, the number of pixels used to draw 1dp is scaled up by a factor appropriate for the screen's dpi. Likewise, when on a lower density screen, the number of pixels used for 1dp is scaled down. The ratio of dp-to-pixel will change with the screen density, but not necessarily in direct proportion. Using dp units (instead of px units) is a simple solution to making the view dimensions in your layout resize properly for different screen densities. In other words, it provides consistency for the real-world sizes of your UI elements across different devices.
sp: Scale-independent Pixels - This is like the dp unit, but it is also scaled by the user's font size preference. It is recommend you use this unit when specifying font sizes, so they will be adjusted for both the screen density and the user's preference.
pt: Points - 1/72 of an inch based on the physical size of the screen.
px: Pixels - Corresponds to actual pixels on the screen. This unit of measure is not recommended because the actual representation can vary across devices; each devices may have a different number of pixels per inch and may have more or fewer total pixels available on the screen.
mm: Millimeters - Based on the physical size of the screen.
in: Inches - Based on the physical size of the screen.

Note: A dimension is a simple resource that is referenced using the value provided in the name attribute (not the name of the XML file). As such, you can combine dimension resources with other simple resources in the one XML file, under one <resources> element.

To make it absolutely clear - try to never use anything but sp or dp unless you absolutely have to. Using sp/dp will make your Android applications compatible with multiple screen densities and resolutions

Resources: http://developer.android.com/guide/topics/resources/more-resources.html#Dimension

Android Developer Tutorials

3:46 PM C4KTeam No comments

Android invasion, Sydney, Australia (Photo credit: Pranav Bhatt)

Building Your First App
After you've installed the Android SDK, start with this class to learn the basics about Android app development.
Managing the Activity Lifecycle
How Android activities live and die and how to create a seamless user experience by implementing lifecycle callback methods.

Supporting Different Devices
How to build your app with alternative resources that provide an optimized user experience on multiple device form factors using a single APK.
Building a Dynamic UI with Fragments
How to build a user interface for your app that is flexible enough to present multiple UI components on large screens and a more constrained set of UI components on smaller screens—essential for building a single APK for both phones and tablets.
Saving Data
How to save data on the device, whether it's temporary files, downloaded app assets, user media, structured data, or something else.
Interacting with Other Apps
How to build a user experience that leverages other apps available on the device to perform advanced user tasks, such as capture a photo or view an address on a map.
Sharing Content
How to take your app interaction to the next level by sharing information with other apps, receive information back, and provide a simple and scalable way to perform Share actions with user content.

Saving Activity state in Android

2:04 PM C4KTeam No comments

The introduction to Managing the Activity Lifecycle briefly mentions that when an activity is paused or stopped, the state of the activity is retained. This is true because the Activity object is still held in memory when it is paused or stopped—all information about its members and current state is still alive. Thus, any changes the user made within the activity are retained so that when the activity returns to the foreground (when it "resumes"), those changes are still there.

You need to override onSaveInstanceState(Bundle savedInstanceState) and write the application state values you want to change to the Bundle parameter like this:

Override
public void onSaveInstanceState(Bundle savedInstanceState) {
  super.onSaveInstanceState(savedInstanceState);
  // Save UI state changes to the savedInstanceState.
  // This bundle will be passed to onCreate if the process is
  // killed and restarted.
  savedInstanceState.putBoolean("MyBoolean", true);
  savedInstanceState.putDouble("myDouble", 1.9);
  savedInstanceState.putInt("MyInt", 1);
  savedInstanceState.putString("MyString", "Welcome back to Android");
  // etc.
}

The Bundle is essentially a way of storing a NVP ("Name-Value Pair") map, and it will get passed in to onCreate and also onRestoreInstanceState where you'd extract the values like this:

@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
  super.onRestoreInstanceState(savedInstanceState);
  // Restore UI state from the savedInstanceState.
  // This bundle has also been passed to onCreate.
  boolean myBoolean = savedInstanceState.getBoolean("MyBoolean");
  double myDouble = savedInstanceState.getDouble("myDouble");
  int myInt = savedInstanceState.getInt("MyInt");
  String myString = savedInstanceState.getString("MyString");
}

You'd usually use this technique to store instance values for your application (selections, unsaved text, etc.).

CAREFUL: you need to call super.onSaveInstanceState(savedInstanceState) before adding your values to the Bundle, or they will get wiped out on that call (Droid X Android 2.2).

The savedInstanceState is only for saving state associated with a current instance of an Activity, for example current navigation or selection info, so that if Android destroys and recreates an Activity, it can come back as it was before. See the documentation for onCreate and onSaveInstanceState
For more long lived state, consider using a SQLite database, a file, or preferences. See Saving Persistent State.

Resources:
http://developer.android.com/guide/components/activities.html
http://stackoverflow.com/questions/151777/saving-activity-state-in-android

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Android Emulator Keyboard Commands

Command Line Parameters

Differences between the px, dip, dp and sp units in Android

Android Developer Tutorials

Building Your First App

Managing the Activity Lifecycle

Supporting Different Devices

Building a Dynamic UI with Fragments

Saving Data

Interacting with Other Apps

Sharing Content

Saving Activity state in Android

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Command Line Parameters

Building Your First App

Managing the Activity Lifecycle

Supporting Different Devices

Building a Dynamic UI with Fragments

Saving Data

Interacting with Other Apps

Sharing Content

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