My aims are to:
- Test the basic development tools on a simple program
- 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.
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
- Oracle JDK 1.7 or later
- Android SDK Tools (just the command line tools)
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:
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.
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)
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)
Run the device:
emulator -avd DEVICE
If the device screen appears to be locked, then swipe to unlock it.
Leave it running while you code the app.
Coding the app
Change to an empty working directory.
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 );
}
}
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>
Make a sub-directory for the declared resources:
mkdir res
Leave it empty for now.
Building the code
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.
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
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.
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).
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.)
Optimize the data alignment of the APK (recommended practice):
zipalign -f -v 4 app.apkUnalign app.apk
Installing and running
Install the app to the Android device:
adb install -r app.apk
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.
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>
Reference the resource from the XML manifest.
This is a declarative style of reference:
<!-- <application a:label='Saying hello'> -->
<application a:label='@string/appLabel'>
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 ));
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
- working example - A working build script that uses the above commands
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.
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>
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)
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
---
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>
# 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
vi buildprj # create a build script
#!/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 ï¾ .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 ï¾ .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 {} +
./buildprj # run the build script
-----pitfalls I had fallen into----
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...
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