A script to safely manage your Android keystore

Just a quick one for you peeps tonight.
So I screwed up and lost the signing key for my latest app. It's not too bad because it was still in beta, not released to the public. I was sure that I took enough precautions, apparently not. I really don't want this to happen again. The only dangerous part is when you are creating new keys, so I wrote a script!  (addkey.sh)

Get it here

This script works in conjunction with ~/.gradle/gradle.properties, which you should use :)  You won't find much use in this script if you don't use gradle.properties.

How to use

First you configure the script by editing it.  Simply fill in the required information at the top of the script. You can also read the usage.

Then when you run the script (no parameters are needed) it will prompt you for a name and password for a new key. 

That's it. The script takes over. 

What the script does

It gets the keystore's location and password from your gradle.properties file, creates the key as required for Android, and then marks the keystore as read-only so you can't screw it up! :D

It then even makes a backup of your keystore.

And then the script presents you with the information you will need for your gradle.build.

I hope that this helps you out!

Building multiple APKs inside Android Studio

Build variants are a huge feature for Android development. The use cases for such a feature are many. It can be as simple as having a free version of your app and a paid version. Or maybe you are making generic software that can be sold to many companies that all want they're own branding.

Whatever your use case may be, Gradle comes to the rescue. Not only can you configure your variants but you can also select which ones actually get built. You are probably already aware of the standard way to do this in Android Studio which is to use the "Build Variants" tool window and select the variant that you want to build.

This builds one variant at a time and is very practical while you are developing as it allows you to quickly switch from one variant to the another.

Once development is done, you will want to build all of your release variants for final testing and distribution. You can do this in Android Studio as well. Simply open the "Gradle Tasks" tool window, which is usually on the right. You will see many tasks that start with 'assemble', double click on one of those and your APKs will be created.

For example, double clicking on 'assembleRelease' will create all your release apks.

From the docs:

Building and Tasks

We previously saw that each Build Type creates its own assemble task, but that Build Variants are a combination of Build Type and Product Flavor.

When Product Flavors are used, more assemble-type tasks are created. These are:

1) assemble[Variant Name]

2) assemble[Build Type Name]

3) assemble[Product Flavor Name]

1) allows directly building a single variant. For instance assembleFlavor1Debug.

2) allows building all APKs for a given Build Type. For instance assembleDebug will build both Flavor1Debug and Flavor2Debug variants.

3) allows building all APKs for a given flavor. For instance assembleFlavor1 will build both Flavor1Debug and Flavor1Release variants.

The task assemble will build all possible variants.

Note the "Recent tasks" section which allows you to quickly execute previously run tasks.

You'll also note that the tasks that you run are added to your Configurations dropdown. This allows you to quickly access them by hitting Shift-F10.

And that's it! I hope that this helps you out.

Localized getString() with parameters

getString

We all know the getString() method which is available in the Resources class and in the Context class. However, did you know that there is also a second version of that method that accepts parameters that will be merged into a format string? You can find the Android documentation here.

Simple example

Here is an example of this version of getString():

In your xml file:

 <string name="hello_person">Hello %1$s, how are you?</string>  

In your Java file:

 String userName = getUserName();  
 String hello = getResources().getString(R.string.hello_person, userName);  

This simplifies your code a lot. And it really is but a convenience at you can see in the source Android code:

 public String getString(int id, Object... formatArgs) throws NotFoundException {  
   String raw = getString(id);  
   return String.format(mConfiguration.locale, raw, formatArgs);  
 }  

Multipe placeholders example

You can also have more than one placeholder in your original string, and you can use more than one type:

In your xml file:

 <string name="hello_person_age">Hello %1$s, you are %2$d years old</string>   

In your Jave file:

 String userName = getUserName();  
 int age = getAge();  
 String hello = getResources().getString(R.string.hello_person_age, userName, age);   

Context class

And how about the version in the Context class?  It just delegates to the method in the Resources class:

 public final String getString(int resId, Object... formatArgs) {  
   return getResources().getString(resId, formatArgs);  
 }  

Thanks to +Wolfram Rittmeyer for tuning me into this version of getString()!

Automating ADB over Wi-Fi for multiple devices

Here is a script that will scan through your Android devices that are connected to ADB via a USB cable and then connect them all via ADB over Wi-Fi.

Usage is very simple.  If needed, modify the script with your IP range and then run the script. You will need to run this script every time you want to connect to your Wi-Fi network.

Note that I haven't yet found a way to test if a device is already connected via Wi-Fi so you may get errors such as "unable to connect to 192.168.1.2:5555:5555".  You'll know that the device is already connected if you see the double port value at the end.

Thanks to +Tony Owen for the original idea and to +Wolfram Rittmeyer with the help on the script.

Please feel free to expand this script or modify it. Let me know if you do so that I can update this post!

 #!/bin/bash  
   
 #Modify this with your IP range  
 MY_IP_RANGE="192\.168\.1"  
   
 #You usually wouldn't have to modify this  
 PORT_BASE=5555  
   
 #List the devices on the screen for your viewing pleasure  
 adb devices  
 echo   
   
 #Find USB devices only (no emulators, genymotion or connected devices  
 declare -a deviceArray=(`adb devices -l | grep -v emulator | grep -v vbox | grep -v "${MY_IP_RANGE}" | grep " device " | awk '{print $1}'`)  
   
 echo "found ${#deviceArray[@]} device(s)"  
 echo   
   
 for index in ${!deviceArray[*]}  
 do  
   echo "finding IP address for device ${deviceArray[index]}"  
   IP_ADDRESS=$(adb -s ${deviceArray[index]} shell ifconfig wlan0 | awk '{print $3}')   
     
   echo "IP address found : $IP_ADDRESS "  
     
   echo "Connecting..."  
   adb -s ${deviceArray[index]} tcpip $(($PORT_BASE + $index))  
   adb -s ${deviceArray[index]} connect "$IP_ADDRESS:$(($PORT_BASE + $index))"  
   
   echo  
   echo  
 done  
   
 adb devices -l  
 #exit