Android building unsigned APK

Just a small Android development tip:

The Android export wizard that comes with Eclipse allows you to build the "release" APK of your application but expects you to have the signing keys at the time of the build, otherwise it doesn't allow to proceed. Sometimes you just need to send the unsigned APK to your client and allow them to sign it later.

The easiest way to accomplish that at the moment is to do the build with Ant (build.xml).
In order to generate the build.xml file you can run the following command in your application directory:
android update project --path .

This will create the build.xml file for you project. Then run:
ant release

and this will create the -release-unsigned.apk in your bin directory.
Sometimes (most of the time) the android tool doesn't pick the right name for the project and you might   end up with something like MainActivity-release-unsigned.apk, in that case just edit the project name property in the build.xml.

Note that if your app depends on the other library projects, then these also need to have the build.xml generated for them.

Code by Brian

My friend Brian started his own Android blog:

Code by Brian

Lots of useful stuff there and there is more to come.

Enjoy!

Great article on Android UI performance by Romain

Stumbled upon this great article on Android UI performance problems detection tools, tips&tricks by Romain Guy on Google+:

http://www.curious-creature.org/docs/android-performance-case-study-1.html

Enjoy!

Mandiant on Android

I went to MIRcon 2012 conference this week and one of speakers was a guy from our company who does some R&D for Android at our New York office.
I found his blog very interesting and just wanted to share here:
http://thecobraden.blogspot.com/

Enjoy! :)

The Easter Egg in Android tools

Try:

aapt dump badger [you app name].apk

and have a nice badger :)

Android NDK8 now with MIPS arch support

With the support for MIPS architecture in the latest release of NDK8, the life of NDK developers became a bit more difficult again. We have 4 architectures to cross-compile a bunch of native libraries for: armebi, armebi-v7a, x86 and mips. I guess, this is just one more push to move towards Java code for better portability and smaller .APKs, etc.

By the way the issue with libc on x86 builds that I was posting about since NDK6 still exists.
One the native libraries that I use fails to build with the following errors:
undefined reference to `siglongjmp'
undefined reference to `sigsetjmp'
See here: http://aleksmaus.blogspot.com/2011/11/more-fun-with-android-ndk7.html

The x86 build fails with both Mac OS X and Linux NDK8.

If anybody on Android NDK team reads this, please, please, please fix it.

Bulding AOSP on Ubuntu 12.04

Update (July, 11, 2012):
Just built the Android 4.1.1 (Jelly Bean) branch from AOSP on Ubuntu 12 with no problems whatsoever. This makes this post no longer relevant.
Many thanks for that to Android development team.

//************************************************************************


I just started to play with Ubuntu 12.04 and stumbled on few issues while building Android source tree (AOSP master branch).

Here are few things that might be useful to know in order get AOSP building:

1. First, follow the instructions here http://source.android.com/source/initializing.html to install all the dependencies and set everything up.

2. Then install Sun JDK6, here is the link to the latest download at the moment:
http://www.oracle.com/technetwork/java/javase/downloads/jdk-6u32-downloads-1594644.html

After downloading it, execute these commands:

$ chmod u+x jdk-6u32-linux-x64.bin
$ ./jdk-6u32-linux-x64.bin
$ sudo mv jdk1.6.0_32 /usr/lib/jvm/
$ sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/jdk1.6.0_32/bin/java" 1
$ sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/jdk1.6.0_32/bin/javac" 1

then switch to this version of java with:
$ sudo update-alternatives --config java
and
$ sudo update-alternatives --config javac

You can probably get away with OpenJDK6 (disable the java version check in the build/core/main.mk). I remember I had a problem compiling one of the CTS tests and fixing that required some java code modifications.

3. The failure while building qtools build can be fixed with changing

common_cflags := -O0 -g 

to

common_cflags := -O0 -g -Wwrite-strings -fpermissive

in the sdks/emulator/qtools/Android.mk

Found here: http://code.google.com/p/android/issues/detail?id=4347

4. The failure with OpenGL libraries linking can be fixed with 

sudo ln -s /usr/lib/x86_64-linux-gnu/mesa/libGL.so.1 /usr/lib/libGL.so

5. The failure while building obbtool, can be fixed in the  

build/core/combo/HOST_linux-x86.mk file by changing the following line

HOST_GLOBAL_CFLAGS += -D_FORTIFY_SOURCE=0

to

HOST_GLOBAL_CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=0

Found here: http://code.google.com/p/android/issues/detail?id=20795

6. The failure with:
make: *** [out/host/linux-x86/obj/STATIC_LIBRARIES/libMesa_intermediates/src/glsl/linker.o] Error 1

can be fixed with adding the 

#include <stddef.h>

at the top of the external/mesa3d/src/glsl/linker.cpp file.

7. The failure external/oprofile/libpp/format_output.h:94:22: error: reference ‘counts’ cannot be declared ‘mutable’ [-fpermissive]

can be fixed by changing the external/oprofile/libpp/format_output.h file

mutable counts_t & counts;

to 

counts_t & counts;

Found here: http://code.google.com/p/android/issues/detail?id=22003

8. The failure external/gtest/src/../include/gtest/internal/gtest-param-util.h:122:11: error: ‘ptrdiff_t’ does not name a type

can be fixed by adding 

#include <cstddef>

into the external/gtest/src/../include/gtest/internal/gtest-param-util.h file. 

9. The failure /external/llvm/lib/Support/Mutex.cpp:143: undefined reference to `pthread_mutex_trylock'
collect2: ld returned 1 exit status
make: *** [out/host/linux-x86/obj/EXECUTABLES/test-librsloader_intermediates/test-librsloader] Error 1

can be fixed by adding 

LOCAL_LDLIBS := -lpthread -ldl 

into external/llvm/llvm-host-build.mk file.

Found here: http://code.google.com/p/android/issues/detail?id=22011

10. For the failure frameworks/compile/slang/slang_rs_export_foreach.cpp:249:23: error: variable ‘ParamName’ set but not used [-Werror=unused-but-set-variable]

I just commented out that line since the ParamName is not used anyways.

This might not be the best solution, but it builds and leaves me some time to improve it if I need it.

Hope this saves you a bit of time.

Android: Updated SDK Tools and ADT revision 17

Google released the new update for Android SDK tools and ADT 17. Lots of yummy goodies inside.

I'm particularly excited about the new x86 emulator image running in virtualization mode (means faster emulator), that what I actually needed to test some of my native libs on x86 architecture.

For more details go to this link:
http://android-developers.blogspot.com/2012/03/updated-sdk-tools-and-adt-revision-17.html

At the end just wanted to add: I'm very impressed how well Google executes on it's Android initiative.

Android: "About those vector icons"

One of my friend, previously Windows programmer, started to do Android development recently and was confused with all the variations of screen densities and resolutions he has to deal with.
The first heated argument was about why Android can't use one-for-all image resource and scale it properly for different densities.
In fact Android actually does this for you, but the result kind of sucks most of the time.

The next argument was why can't they use the vector graphics for the images.
I remember I was looking into this myself long time ago and found an article with very detailed explanation, thanks to Kirill Grouchnikov. Posting it here so I don't forget the next time where it is:
http://www.pushing-pixels.org/2011/11/04/about-those-vector-icons.html

Ant macros for Git checkout

...just stumbled upon a couple of useful macros for git checkout here :

http://tlrobinson.net/blog/2008/11/ant-tasks-for-git/

<macrodef name = "git">
    <attribute name = "command" />
    <attribute name = "dir" default = "" />
    <element name = "args" optional = "true" />
    <sequential>
        <echo message = "git @{command}" />
        <exec executable = "git" dir = "@{dir}">
            <arg value = "@{command}" />
            <args/>
        </exec>
    </sequential>
</macrodef>
<macrodef name = "git-clone-pull">
    <attribute name = "repository" />
    <attribute name = "dest" />
    <sequential>
        <git command = "clone">
            <args>
                <arg value = "@{repository}" />
                <arg value = "@{dest}" />
            </args>
        </git>
        <git command = "pull" dir = "@{dest}" />
    </sequential>
</macrodef>

Samsung Galaxy Tab 10.1 - Stuck on Boot (link to article)

My Samsung Tablet "has died" today. It got stuck on boot for some reason.

I hooked it up to the computer and checked the logcat (adb logcat). 

It was trying to open the account database on the device, that for some reason got corrupted and after the failing to do so (unable to open database file, db=/data/system/accounts.db) it rebooted over and over again. The database can be easily fixed on the rooted device, but mine was not rooted yet.

After a bit of googling I found this useful article that describes exactly the same problem on exactly the same device and provides the solution:

http://mrkn.co/forums/android/general/364.html

Essentially, the solution comes down to deleting all the user data (aka factory reset), here are the steps from the article:

"In case you are wondering how to hard-reset your tab, you can follow these steps:

1) Power off the device by holding the power key for about 8 seconds
2) Press the volume down key (the one to the left, as I always confuse them) and then the power key
3) Within a couple of seconds, you'll see two logos on the device, one for USB and another, that looks like a Android dude shoveling earth
4) Press the the volume down button to select the the USB icon, and then press the volume up button to make the actual selection
5) Your device is now in the "fastboot" mode
6) Finally, open up your terminal/shell and type fastboot -w, which will completely erase your userdata and cache partitions (took about 12.5 seconds for me). I got the fastboot by building it from source, but you can download pre-built binaries from various sources on the web
7) Restart your device
8) You should now be prompted to set it up... all over again"

Many thanks to the author of that article Aleksandar Gargenta. 

YAML parser for Android

I needed YAML parser for Android this week and after a bit of research I found that SnakeYAML might work: http://code.google.com/p/snakeyaml
The only problem was if you try to use the latest code the application would fail with exception that looks something like this in the logcat:

VFY: unable to resolve exception class 21 (Ljava/beans/IntrospectionException;)

This happens due to the dependency on java.bean package APIs that is used to parse getters/setters types of properties (methods). 

There is a prebuilt library already available in the download section for version 1.8 adjusted for Android: http://snakeyaml.googlecode.com/files/snakeyaml-android-1.8-SNAPSHOT.jar (thanks to Alexander Maslov), but I wanted to use the latest code. 

The adjustment for Android is quite straight forward:

* Remove all the imports of java.bean package components

* Remove the throws IntrospectionException from methods declarations in few files (grep, there are only 4 .java files to change 

* In the introspector/PropertyUtils.java adjust the getPropertiesMap method implementation, throw away the use of Introspector. Yep, the library will not support java getters/setters methods serialization after that, only fields, but that worked fine for me.

* Remove introspector/MethodProperty.java file

* If you want to save some time and don't care building and running tests (I know it's wrong, but still), then you can build the .jar library with mvn package -DskipTests=true command.

* Add the final .jar file into your Android project and enjoy YAML on Android

Update (02-22-2012):

Alexander just landed the patches for Android (http://code.google.com/p/snakeyaml/source/list).
Now the latest source code can be easily built with one command: mvn package -Pandroid or to skip the tests mvn package -Pandroid -DskipTests=true. After the build,  just use snakeyaml-1.11-SNAPSHOT-android.jar.

PipedInputStream default size on Android

The PipedInputStream on Android is 1024 bytes by default.

protected static final int PIPE_SIZE = 1024;

In many cases this value is too small, so the constructor with the size parameter should be used instead.

Android application signing with PKCS12 (.p12) certificate

Here are few useful commands to sign the Android application with PKCS12 certificate.

* Import PKCS12 cert into keystore file:

keytool -importkeystore -srckeystore mycert.p12 -destkeystore mycert.keystore -srcstoretype pkcs12

* Change the certificate alias in the keystore if you like:

keytool -changealias -keystore mycert.keystore -destalias new_cert_alias -alias original_cert_alias

* List the keystore certificates (-v for verbose)

keytool -list -v -keystore mycert.keystore

* Sign the Android APK

jarsigner -verbose -keystore mycert.keystore myapp.apk cert_alias

* Verify that the APK is signed

jarsigner -verify -verbose -certs myapp.apk

OAuth2 with Google C2DM (push)

I had to implement the server prototype for Google C2DM (push) the other day.

The easiest option to get the auth token is to use ClientLogin API: http://code.google.com/apis/accounts/docs/AuthForInstalledApps.html  that returns the auth token in one call. One of the problems with this approach was that I either had to store the credentials on the server in order to refresh the auth token if it expires or notify the system administrator to go ahead and re-authenticate through the dedicated web page on the server. 

The better approach is to use OAuth2 API instead: http://code.google.com/apis/accounts/docs/OAuth2WebServer.html. 

There are couple of things are not well documented:

* When you register the app on the https://code.google.com/apis/console/ there is no C2DM service API to choose. That's fine for now, though it might change later probably.

* One of the parameters "scope" for the https://accounts.google.com/o/oauth2/auth call needs to be set to 

scope=https%3A%2F%2Fandroid.apis.google.com%2Fc2dm (https://android.apis.google.com/c2dm url-encoded)

* Set parameter access_type=offline.This will provide you with the refresh_token in the authentication response, that you can use to renew the auth token when it expires. 

Hope this will save somebody few minutes. 

UPDATE (January 19, 2012):
If you stumble upon the MismatchSenderID error, make sure that when you start authentication (https://accounts.google.com/o/oauth2/auth) that you are not already signed in under your personal google account (hint: the browser cookies) . You should be signed under the google account that you created and that got approved for C2DM.

UPDATE (July 2, 2012):
As of the Google IO 2012 the C2DM API is officially deprecated and this article is not really that relevant anymore.
The new sign ups and the quota increase requests are not going to be processed anymore and Google highly recommends to migrate over to the Google Cloud Messaging (GCM), which is still free and has lots of improvements and additional features. I personally think GCM is awesome. 
Please refer to the official GCM page for more details:
http://developer.android.com/guide/google/gcm/index.html

I'm looking forward to change my code to work with GCM pretty soon and will try to write another post on the transition process. Enjoy!

Missing pthread_mutex_timedlock on Android

I stumbled upon a problem today that the pthread_mutex_timedlock function definition is missing on Android, though it's declared in the pthread.h.
The first thought was to implement it as a loop with a call to pthread_mutex_trylock and some sleep until we are able to get the lock or until the timeout happens, felt a bit awkward.

I took a look a the Mono for Android source code and that's exactly what they do there (./mono/io-layer/mono-mutex.c), so go figure, looks like this solution might not be that bad after all.


Here is how it's implemented in Mono for example:

int
pthread_mutex_timedlock (pthread_mutex_t *mutex, CONST_NEEDED struct timespec *timeout)
{
 struct timeval timenow;
 struct timespec sleepytime;
 int retcode;
 
 /* This is just to avoid a completely busy wait */
 sleepytime.tv_sec = 0;
 sleepytime.tv_nsec = 10000000; /* 10ms */
 
 while ((retcode = pthread_mutex_trylock (mutex)) == EBUSY) {
  gettimeofday (&timenow, NULL);
  
  if (timenow.tv_sec >= timeout->tv_sec &&
      (timenow.tv_usec * 1000) >= timeout->tv_nsec) {
   return ETIMEDOUT;
  }
  
  nanosleep (&sleepytime, NULL);
 }
 
 return retcode;
}

How to setup Eclipse for debugging with Android NDK

Just wanted to bookmark couple of useful links on how to setup Eclipse IDE for debugging with NDK. Sometimes it might be more convenient than doing ndk-gdb from terminal, that I still didn't quite get used to yet. It took a bit of time and few tries to get things going. I had some problems with symbols loading and matching, and finally succeeded. Anyways if stuck check comments to these articles. 

1. Setup your project to be a mixed Java, C, and C++ project:
   http://mhandroid.wordpress.com/2011/01/23/using-eclipse-for-android-cc-development/
2. Setup your project to enable debugging:
   http://mhandroid.wordpress.com/2011/01/23/using-eclipse-for-android-cc-debugging/#more-23

Android NDK logging

Just wanted to share the snipped that often used in the different Android native projects.

The following are some useful macros for logging with NDK.

#include<android/log.h>

#define LOGD(LOG_TAG, ...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)

#define LOGV(LOG_TAG, ...) __android_log_print(ANDROID_LOG_VERBOSE, LOG_TAG, __VA_ARGS__)

#define LOGE(LOG_TAG, ...) __android_log_print(ANDROID_LOG_ERROR, LOG_TAG, __VA_ARGS__)

You can define more as needed just take a look at the android/log.h header file for all available priority values.

Then I would usually define log TAG:

#define LOG_TAG "MyModule"

and use the macros like this:

LOGD(LOG_TAG, "my val: %s", val);

fopen with native library on Android

If you develop an Android application with some native C/C++ layer (NDK) and 

try to open the file from it by doing FILE *pFile = fopen ("myfile.txt" ,"w");

the fopen call will fail.

The reason is that the current working directory for you application is the root of file system '/' and naturally your application doesn't have access to it.

In order to fix this problem you have to pass the full path for the file to fopen call.

One way to do this is to pass the base path to your application data folder where your application has read/write permissions. For example you can use the Context API getFilesDir().getAbsolutePath()

http://developer.android.com/reference/android/content/Context.html#getFilesDir()

and pass the result to the native function call.

This particular API resolves currently into something like: "/data/data/[app package]/files/"

In your native code then the fopen call should succeed with 

FILE *pFile = fopen ("/data/data/[app package]/files/myfile.txt" ,"w"); 

Hope this was helpful.

More fun with Android NDK7

I tried to compile cURL library Android NDK7 for x86 architecture and it looks like though the bug was reported in NDK6b: http://code.google.com/p/android/issues/detail?id=19851, the libc is still missing few functions sigsetjmp and siglongjmp.
The easiest solution for me was to get the libc from the latest ICS source tree (built for x86 arch).

Looking forward to get this fixed in NDK8, hopefully before Christmas.