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December 4, 2007

Command line Java on DalvikVM

Found this very useful when i was trying out the JNI under android (Short Story – Could not get it to work!).

Step #1: Start with a simple java class

package org.apache;



public class HelloWorld {

    public static void main(String[] args) {

        System.out.println("Hello World!");

    }

}

Compile the java class

C:\android\CmdLine>javac -d . -g Helloworld.java

Step #2: Package the generated classes into a temporary jar

C:\android\CmdLine>jar -cvf Temp.jar *

added manifest

adding: Hello.java(in = 0) (out= 0)(stored 0%)

adding: HelloWorld.java(in = 149) (out= 122)(deflated 18%)

adding: org/(in = 0) (out= 0)(stored 0%)

adding: org/apache/(in = 0) (out= 0)(stored 0%)

adding: org/apache/HelloWorld.class(in = 556) (out= 344)(deflated 38%)

Step #3: Use the “dx” tool to generate a classes.dex from our temporary jar.

C:\android\CmdLine>dx --dex --output=c:/android/CmdLine/classes.dex c:/android/CmdLine/Temp.jar

Step #4: Use the “aapt” tool to create a new jar suitable for use with dalvikvm

C:\android\CmdLine>aapt add CmdLine.jar classes.dex

 'classes.dex'...

and push it into a known location on the emulator

C:\android\CmdLine>adb push CmdLine.jar /data

30 KB/s (0 bytes in 481.000s)

Step #5: kick the tires of dalvikvm

C:\android\CmdLine>adb shell

# /system/bin/dalvikvm -Xbootclasspath:/system/framework/core.jar -version

/system/bin/dalvikvm -Xbootclasspath:/system/framework/core.jar -version

DalvikVM version 0.2.0

Copyright (C) 2007 Google, Inc.

Blah blah blah LICENSE blah blah.

Dalvik VM init failed (check log file)

Step #6: Run our code

# /system/bin/dalvikvm -Xbootclasspath:/system/framework/core.jar -classpath /data/CmdLine.jar org.apache.HelloWorld

/system/bin/dalvikvm -Xbootclasspath:/system/framework/core.jar -classpath /data/CmdLine.jar org.apache.HelloWorld

Hello World!



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http://android-developers.blogspot.com/ 블로그에서 NDK를 키워드로 기사를 검색해서 4개의 포스트를 찾았다. 4개 기사의 내용을 요약한다. 영어다. 갑갑한가? 나는 환장하겠다. 당분간 영어로 포스트를 올리게 될 것 같다. -_-;;

http://android-developers.blogspot.com/2010/05/android-22-and-developers-goodies.html
"Android 2.2 and developers goodies."
Posted by Xavier Ducrohet, Android SDK Tech Lead on 20 May 2010 at 9:00 AM
 - 20/May/2010 Android 2.2 announced. (7th platform release since Android 1.0)
 - (on the native side,) add new APIs to access Skia bitmap
 - tools update
  - Android SDK Tools, Revision 6, Eclipse plug-in 0.9.7
  - Android NDK, Revision 4

http://android-developers.blogspot.com/2010/03/android-ndk-r3.html
"Android NDK r3"
Posted by David Turner on 08 March 2010 at 11:25 AM
 - NDK r3 can used to target devices running Android 1.5 and higher
 - use GCC 4.4.0 (previously used GCC 4.2.1)
  so, generate slightly more compact and efficient machine code
 - support OpenGL ES 2.0

http://android-developers.blogspot.com/2009/09/now-available-android-16-ndk.html
"Now available: Android 1.6 NDK"
Posted by David Turner on 29 September 2009 at 10:00 AM
 - NDK is a companion to SDK
 - NDK is used to generate and embed ARM machine code within your App Package
 - NDK 1.6 features
  - support OpenGL ES 1.1
  - many fixes to the NDK build scripts

http://android-developers.blogspot.com/2009/06/introducing-android-15-ndk-release-1.html
"Introducing Android 1.5 NDK, Release 1"
Posted by David Turner on 25 June 2009 at 10:30 AM
 - finally, android App-developers can use native code for their App
 - provide libc, libm, JNI, libz, and liblog libraries


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