CODEWITHSUNDEEP
androidandroid-build
Michael Allan
Michael Allan

Reputation: 3921

Hello world using the Android SDK alone (no IDE)

My aims are to:

  1. Test the basic development tools on a simple program
  2. Expand the program into a useful app

I prefer to work with small, independent tools as opposed to IDEs. I prefer to code in a procedural or imperative style (plain old Java) as opposed to declarative (XML).

I installed the stand-alone Android SDK as instructed. I have the necessary minimum of other tools (text editor, command shell and JDK). But the only starting instructions I can find are tied to Android Studio, Eclipse or other IDEs. I can't follow them.

How can I write a Java program with my text editor to display "Hello world" on an Android device? How can I test it using the SDK emulator? Please give me instructions.

Upvotes: 21

Views: 4926

Answers (5)

I.F.F. dos Santos
I.F.F. dos Santos

Reputation: 1

The command dx is now unavailable and the Apk Builder needs to configure a key. This is my settings...

Installations

Firt you need the Software Developer Kit (SDK), the Java Developer Kit (JDK) and a key file.

  1. To use SDK without IDE download the Command line tools here.
  2. Uncompress the Command line tools (e.g. unzip commandlinetools-linux.zip).
  3. Move the directory cmdline-tools for a convenient location and rename it to SDK (e.g. mv cmdline-tools ~/.android/SDK).
  4. Go to SDK/bin and run (see note 1)
./sdkmanager --sdk_root=../ --list
./sdkmanager --sdk_root=../ "platforms;android-31"
./sdkmanager --sdk_root=../ platform-tools
./sdkmanager --sdk_root=../ "build-tools;31.0.0"
  1. Download the JDK version 11 here (>11 do not work for android java virtual machine).
  2. Uncompress the JDK in a convenient directory and rename it to JDK (e.g. unzip openjdk-11.zip ; mv jdk-11 ~/.android/JDK).
  3. Go to JDK/bin and make a key with ./keytool -genkey -keystore ~/.keystore -keyalg RSA.
  4. Make an script to compile your applications. For example (see note 2)
#!/bin/bash

# Script to compile a android application source.
# The argument of the scrit is the directory of the source code (e.g. `ac hello_world/`),
# this directory may be have the file `AndroidManifest.xml`, the `res` directory
# and subdirectories containing the java source files.

cd "$1"

# ###
# seting up the ambient variables
# ###
export JAVA_HOME="$HOME/.android/JDK"
export ANDROID_HOME="$HOME/.android/SDK"

export ANDROID_PLATFORM="$ANDROID_HOME/platforms/android-31"
export ANDROID_BUILD_TOOLS="$ANDROID_HOME/build-tools/31.0.0"
export ANDROID_TOOLS="$ANDROID_HOME/tools"

export PATH=$JAVA_HOME/bin:$ANDROID_BUILD_TOOLS:$ANDROID_TOOLS:$PATH

# ###
# Compile the code
# ###

# Compile the source code to Java bytecode (.java to .class)
javac -cp $ANDROID_PLATFORM/android.jar $(find . -name "*.java")

# Translate the bytecode from Java to Android (.class to .dex)
d8 --lib $ANDROID_PLATFORM/android.jar $(find . -name "*.class")

# Package up the resource files, including the manifest
aapt package -f \
-F app.apkPart \
-I $ANDROID_PLATFORM/android.jar \
-M AndroidManifest.xml \
-S res/

# Make the full APK using the `ApkBuilder` tool
CLASSPATH=$ANDROID_TOOLS/lib/* java \
com.android.sdklib.build.ApkBuilderMain app.apkUnalign \
-u -f classes.dex -z app.apkPart

# Optimize the data alignment of the APK
zipalign -f 4 app.apkUnalign app_aligned.apk

# Signer the APK
apksigner sign --ks ~/.keystore --out app.apk app_aligned.apk

# ###
# Remove generated files
# ###
rm app.apkUnalign
rm app_aligned.apk
rm app.apkPart
rm classes.dex
find . -name "*.class" -exec rm {} +

exit 0
  1. Put the script in a bin directory (e.g. ~/bin/ac of /bin/ac were ac is the script name) and make it executable (e.g. chmod 755 ~/ac).

Notes:

  1. platforms;android-31 and build-tools;31.0.0 say "Download tools to API 31 of android" but you can download another version, see disponible versions with ./sdkmanager --sdk_root=../ --list | grep "platforms;android" and ./sdkmanager --sdk_root=../ --list | grep "build-tools;".
  2. This script supose that you put the SDK and the JDK in ~/.android/SDK and ~/.android/JDK and supose that you downloaded the tools for android API 31.

Read more:

Coding

You need basicaly two files, the AndroidManifest.xml and the MainActivity.java. Eventually you need resources, for more advanced programs, in a directory called res, for this example the res directory are empty.

The content of AndroidManifest.xml is like the following.

<?xml version='1.0'?>

<manifest xmlns:android='http://schemas.android.com/apk/res/android'
   package='com.your_company.app'
   android:versionCode='0'>

   <application
      android:label='App name'>

      <activity
         android:name='com.your_company.app.MainActivity'>
         <intent-filter>
            <category android:name='android.intent.category.LAUNCHER'/>
            <action android:name='android.intent.action.MAIN'/>
         </intent-filter>
      </activity>

   </application>

</manifest>

The content of MainActivity.java is like the following.

package com.your_company.app;

import android.app.Activity;
import android.widget.TextView;
import android.os.Bundle;

public final class MainActivity extends Activity {
   @Override
   protected void onCreate(final Bundle activityState){
      super.onCreate(activityState);
      final TextView textV = new TextView(MainActivity.this);
      textV.setText("Hello World");
      setContentView( textV );
   }
}

Is common to put the file MainActivity.java in a directory called src/com/your_company/app/. The file tree looks like the following.

hello_world/
 |
 |--- AndroidManifest.xml
 |--- res/
 |--- src/
       |--- com/
             |--- your_company/
                   |--- app/
                         |--- MainActivity.java

Suposing that you have a command that you inform the source directory and the command invokes a compiler for your source (see the section installations item 8) and the command name are ac, open the directory hello_world in a terminal and type

ac ./

Now copy the file app.apk to your phone and install it.

Upvotes: 0

smokeink
smokeink

Reputation: 111

Since Jack and Jill are outdated, I had to modify a few commands.

Installed the sdk,ndk in /a (the ndk is not used in this hello world), the jdk in the system, and the android-tools-adb in the /usr/bin etc (this one contains adb and fastboot and phone definitions so that it can detect them).

I added this to .bashrc:

export JAVA_HOME=/usr/lib64/java
export ANDROID_HOME=/a
export ANDROID_PLATFORM=$ANDROID_HOME/platforms/android-23
export ANDROID_BUILD_TOOLS=$ANDROID_HOME/build-tools/28.0.0-rc1
export ANDROID_NDK=$ANDROID_HOME/ndk
export ANDROID_TOOLS=$ANDROID_HOME/tools # sdk tools
PATH=$PATH:$JAVA_HOME/bin:$ANDROID_HOME:$ANDROID_BUILD_TOOLS:$ANDROID_NDK:$ANDROID_TOOLS:$ANDROID_TOOLS/bin:$ANDROID_PLATFORM

Here are my modified commands:

sdkmanager --list
sdkmanager "platforms;android-23"
sdkmanager platform-tools

mkdir /a/prj
cd /a/prj
mkdir --parents src/dom/domain
vi src/dom/domain/SayingHello.java

package dom.domain;
import android.widget.TextView;

public final class SayingHello extends android.app.Activity
{
    protected @Override void onCreate( final android.os.Bundle activityState )
    {
        super.onCreate( activityState );
        final TextView textV = new TextView( SayingHello.this );
        textV.setText( "Hello world" );
        setContentView( textV );
    }
}

vi AndroidManifest.xml
<?xml version='1.0'?>
<manifest xmlns:a='http://schemas.android.com/apk/res/android'
 package='dom.domain' a:versionCode='0' a:versionName='0'>
    <application a:label='Saying hello'>
        <activity a:name='dom.domain.SayingHello'>
             <intent-filter>
                <category a:name='android.intent.category.LAUNCHER'/>
                <action a:name='android.intent.action.MAIN'/>
                </intent-filter>
            </activity>
        </application>
    </manifest>

If you choose to use the res/ directory instead, adapt the source code and AndroidManifest.xml as shown below:

# this section is OPTIONAL , the hello world can run without any res
mkdir res/values -p
vi res/values/values.xml
<?xml version='1.0'?>
<resources>
    <string name='appLabel'>Saying hello</string>
</resources>
# Reference the resource from the AndroidManifest.xml manifest.
vi AndroidManifest.xml
<!-- <application a:label='Saying hello'> --> <!-- edit this -->
     <application a:label='@string/appLabel'>

vi src/dom/domain/SayingHello.java
// v.setText( "Hello world" );    // edit this
   v.setText( "This app is called "
     + getResources().getString( R.string.appLabel ));
# end OPTIONAL section

I also created a build script, buildprj:

#!/bin/bash

#Generate the source for the resource declarations. 
aapt package -f \
  -I $ANDROID_PLATFORM/android.jar \
  -J src -m \
  -M AndroidManifest.xml -S res -v

#Compile the source code to Java bytecode (.java ﾆ .class)
javac \
  -bootclasspath $ANDROID_PLATFORM/android.jar \
  -classpath src -source 1.7 -target 1.7 \
  src/dom/domain/*.java

#Translate the bytecode from Java to Android (.class ﾆ .dex)
dx --dex --output="classes.dex" src

#Package up the resource files, including the manifest
aapt package -f -F app.apkPart -I $ANDROID_PLATFORM/android.jar \
-M AndroidManifest.xml -S res -v

#Make the full APK using the ApkBuilder tool:
CLASSPATH=$ANDROID_TOOLS/lib/* java  \
com.android.sdklib.build.ApkBuilderMain app.apkUnalign \
-d -f classes.dex -v -z app.apkPart

#Optimize the data alignment of the APK (recommended practice https://developer.android.com/studio/command-line/zipalign.html ):
zipalign -f -v 4 app.apkUnalign app.apk

adb install -r app.apk
adb shell am start -n dom.domain/.SayingHello

echo "To uninstall the app: adb uninstall dom.domain"
# cleanup
rm app.apkPart app.apkUnalign classes.dex
find . -name "*.class" -exec rm {} +
find . -name "R.java" -exec rm {} +

To run the build script, just call it:

./buildprj # run the build script

Along the way I ran into some pitfalls:

java -classpath $ANDROID_TOOLS/lib/sdklib.jar \
  com.android.sdklib.build.ApkBuilderMain \
  app.apkUnalign \
  -d -f classes.dex -v -z app.apkPart 
it gave an error that didn't say "sdklib.jar doesn't exist/is not found" 
Error: Could not find or load main class com.android.sdklib.build.ApkBuilderMain
... :( 

cd /a/tools/lib/
ln -s sdklib-25.3.1.jar sdklib.jar

java -classpath $ANDROID_TOOLS/lib/sdklib.jar \
  com.android.sdklib.build.ApkBuilderMain \
  app.apkUnalign \
  -d -f classes.dex -v -z app.apkPart 
Exception in thread "main" java.lang.NoClassDefFoundError: com/android/prefs/AndroidLocatio

java -classpath $ANDROID_TOOLS/lib/sdklib.jar \
  com.android.sdklib.build.ApkBuilderMain \
  app.apkUnalign \
  -d -f classes.dex -v -z app.apkPart --help
THIS TOOL IS DEPRECATED. See --help for more information.
Unknown argument: --help

Wow...

Anyway it turns out it 's just explaining that the CLI (ApkBuilderMain) is deprecated in favour of directly calling the Java API (ApkBuilder). If you know how to do that from the command line, please update this example. UPDATE:Actually it seems impossible to do that from the command line so that warning is a bit strange...

"If --help fails with an ArrayIndexOutOfBoundsException, then instead pass no arguments:

java -classpath SDK/tools/lib/sdklib.jar \
  com.android.sdklib.build.ApkBuilderMain
" all right...

Upvotes: 1

Michael Allan
Michael Allan

Reputation: 3921

These are the instructions that eventually worked for me. I got them by deconstructing Google's Ant script, on which Rob's answer is based.

The following content is from "Android programming without an IDE" from Stack Overflow Documentation (archived here); copyright 2017 by geekygenius, Michael Allan, cascal, Doron Behar, mnoronha, and AndroidMechanic; licensed under CC BY-SA 3.0. An archive of the full Stack Overflow Documentation content can be found at archive.org, in which this example is indexed by its topic ID: 85, as example: 9496.

This is a minimalist Hello World example that uses only the most basic Android tools.

Requirements and assumptions

This example assumes Linux. You may have to adjust the syntax for your own platform.

Setting up the Android SDK

After unpacking the SDK release:

  1. Install additional packages using the SDK manager. Don't use android update sdk --no-ui as instructed in the bundled Readme.txt; it downloads some 30 GB of unnecessary files. Instead use the interactive SDK manager android sdk to get the recommended minimum of packages.

  2. Append the following JDK and SDK directories to your execution PATH. This is optional, but the instructions below assume it.

    • JDK/bin
    • SDK/platform-tools
    • SDK/tools
    • SDK/build-tools/LATEST (as installed in step 1)

  3. Create an Android virtual device. Use the interactive AVD Manager (android avd). You might have to fiddle a bit and search for advice; the on-site instructions aren't always helpful.

    (You can also use your own device)

  4. Run the device:

    emulator -avd DEVICE

  5. If the device screen appears to be locked, then swipe to unlock it.

    Leave it running while you code the app.

Coding the app

  1. Change to an empty working directory.

  2. Make the source file:

    mkdir --parents src/dom/domain
touch src/dom/domain/SayingHello.java

    Content: 

    package dom.domain;
import android.widget.TextView;

public final class SayingHello extends android.app.Activity
{
    protected @Override void onCreate( final android.os.Bundle activityState )
    {
        super.onCreate( activityState );
        final TextView textV = new TextView( SayingHello.this );
        textV.setText( "Hello world" );
        setContentView( textV );
    }
}

  3. Add a manifest:

    touch AndroidManifest.xml

    Content: 

    <?xml version='1.0'?>
<manifest xmlns:a='http://schemas.android.com/apk/res/android'
 package='dom.domain' a:versionCode='0' a:versionName='0'>
    <application a:label='Saying hello'>
        <activity a:name='dom.domain.SayingHello'>
             <intent-filter>
                <category a:name='android.intent.category.LAUNCHER'/>
                <action a:name='android.intent.action.MAIN'/>
                </intent-filter>
            </activity>
        </application>
    </manifest>

  4. Make a sub-directory for the declared resources:

    mkdir res

    Leave it empty for now.

Building the code

  1. Generate the source for the resource declarations. Substitute here the correct path to your SDK, and the installed API to build against (e.g. "android-23"):

    aapt package -f \
  -I SDK/platforms/android-API/android.jar \
  -J src -m \
  -M AndroidManifest.xml -S res -v

    Resource declarations (described further below) are actually optional. Meantime the above call does nothing if res/ is still empty.

  2. Compile the source code to Java bytecode (.java → .class):

    javac \
  -bootclasspath SDK/platforms/android-API/android.jar \
  -classpath src -source 1.7 -target 1.7 \
  src/dom/domain/*.java

  3. Translate the bytecode from Java to Android (.class → .dex):

    First using Jill (.class → .jayce):

    java -jar SDK/build-tools/LATEST/jill.jar \
  --output classes.jayce src

    Then Jack (.jayce → .dex):

    java -jar SDK/build-tools/LATEST/jack.jar \
  --import classes.jayce --output-dex .

    Android bytecode used to be called "Dalvik executable code", and so "dex".

    You could replace steps 11 and 12 with a single call to Jack if you like; it can compile directly from Java source (.java → .dex). But there are advantages to compiling with javac. It's a better known, better documented and more widely applicable tool.

  4. Package up the resource files, including the manifest:

    aapt package -f \
  -F app.apkPart \
  -I SDK/platforms/android-API/android.jar \
  -M AndroidManifest.xml -S res -v

    That results in a partial APK file (Android application package).

  5. Make the full APK using the ApkBuilder tool:

    java -classpath SDK/tools/lib/sdklib.jar \
  com.android.sdklib.build.ApkBuilderMain \
  app.apkUnalign \
  -d -f classes.dex -v -z app.apkPart

    It warns, "THIS TOOL IS DEPRECATED. See --help for more information." If --help fails with an ArrayIndexOutOfBoundsException, then instead pass no arguments:

    java -classpath SDK/tools/lib/sdklib.jar \
  com.android.sdklib.build.ApkBuilderMain

    It explains that the CLI (ApkBuilderMain) is deprecated in favour of directly calling the Java API (ApkBuilder). (If you know how to do that from the command line, please update this example.)

  6. Optimize the data alignment of the APK (recommended practice):

    zipalign -f -v 4 app.apkUnalign app.apk

Installing and running

  1. Install the app to the Android device:

    adb install -r app.apk

  2. Start the app:

    adb shell am start -n dom.domain/.SayingHello

    It should run and say hello.

That's all. That's what it takes to say hello using the basic Android tools.

Declaring a resource

This section is optional. Resource declarations aren't required for a simple "hello world" app. If they aren't required for your app either, then you could streamline the build somewhat by omitting step 10, and removing the reference to the res/ directory from step 13.

Otherwise, here's a brief example of how to declare a resource, and how to reference it.

  1. Add a resource file:

    mkdir res/values
touch res/values/values.xml

    Content: 

    <?xml version='1.0'?>
<resources>
    <string name='appLabel'>Saying hello</string>
</resources>

  2. Reference the resource from the XML manifest. This is a declarative style of reference: 

    <!-- <application a:label='Saying hello'> -->
     <application a:label='@string/appLabel'>

  3. Reference the same resource from the Java source. This is an imperative reference: 

    // v.setText( "Hello world" );
   v.setText( "This app is called "
     + getResources().getString( R.string.appLabel ));

  4. Test the above modifications by rebuilding, reinstalling and re-running the app (steps 10-17).

    It should restart and say, "This app is called Saying hello".

Uninstalling the app

adb uninstall dom.domain

See also

Upvotes: 16

slkpg
slkpg

Reputation: 23

Very helpful post. I made a simple brightness setter using your very good instructions. Just wish I could figure out the args for just Jack alone. Was able to put everything in one directory except for the icon which needed to go in res\drawable-hdpi to be found.

javac -bootclasspath c:\android\SDK/platforms/android-19/android.jar -classpath . *.java
java -jar c:\android\SDK/build-tools/24.0.1/jill.jar --output classes.jayce .
java -jar c:\android\SDK/build-tools/24.0.1/jack.jar --import classes.jayce --output-dex .
aapt package -f -F app.apkPart -I c:\android\SDK/platforms/android-19/android.jar -M AndroidManifest.xml -S res -v
java -classpath c:\android\SDK/tools/lib/sdklib.jar com.android.sdklib.build.ApkBuilderMain app.apkUnalign -d -f classes.dex -v -z app.apkPart
zipalign -f -v 4 app.apkUnalign brite.apk

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="dom.domain"
    android:versionCode="1"
    android:versionName="1.0" >
    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="19" />
<uses-permission android:name="android.permission.WRITE_SETTINGS"></uses-permission>
    <application
        android:allowBackup="true"
        android:icon="@drawable/slkimage"
        android:label="brite" >
        <activity
            android:name="dom.domain.MainActivity"
            android:label="brite" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

Upvotes: 1

Rob
Rob

Reputation: 11733

First off, seriously do not even consider using the emulator. Unless you just want to submit to needless torture. For someone who doesn't want the baggage of an IDE, the Emulator is 100x worse. Get a device would be advice on that point.

You are not going to be able to forego XML. I understand and appreciate that impulse I had a similar one. However, I eventually came to love it. Use styles a lot. I would recommend using Android Studio. It has a great lint tool for the code and the interface builder markup.

Even if you want to just code from an editor, you might want to use Android Studio to make your project stub. It's pretty good at that. In case you didn't know this, in the docs, there is a command line way to make a project (not using AS): it's documented here.

Upvotes: 2

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