Some adb Commands for Android Debugging

• Stop an Android app

  $adb shell am force-stop com.my.app.pkg
  

• Uninstall a package

  $adb uninstall com.my.app.pkg
  

• Install a package

  $adb install path/to/pkg/com.my.app.pkg
  

Get Started with JNI

Step 1: Create a Java test file JNITest.java

public class JNITest {
    public native void printString();

    static {
        System.loadLibrary("printstr");
    }   

    public void print() {
        printString();
    }   

    public static void main(String args[]) {
        (new JNITest()).print();
    }   
}

Step 2: Compile the Java file and generate a header file JNITest.h

$javac JNITest.java
$javah -jni JNITest

Step 3: Create a C test file printstr.c

#include <stdio.h>
#include <jni.h>
#include "JNITest.h"

JNIEXPORT void JNICALL Java_JNITest_printString (JNIEnv* env, jobject obj)
{
    printf("Hello, World!\n");
}

Step 4: Compile C file to produce the native lib "libprintstr.jnilib"

$gcc -dynamiclib -o libprintstr.jnilib -I/System/Library/Frameworks/JavaVM.framework/Headers printstr.c -framework JavaVM

Step 5: Run the Java test, which would show "Hello World!"

$java JNITest

First Try of Inserting Source Codes

Hightlight the source code with google code-prettify in two simple steps:

1. add the following script to the HTML file:

   <script src="https://google-code-prettify.googlecode.com/svn/loader/run_prettify.js"></script>

2. wrap the code piece with <pre class="prettyprint"> </pre> tag pair

Hello World in Java

public class Test {
  public static void main(String args[]) {
    System.out.println("Hello World!");
  }
}

Hello World in C

include <stdio.h>

int main() {
  printf("Hello World!");
  return 0;
}

Hello World in C++

include <iostream>
using namespace std;

int main() {
  cout<<"Hello World!";
  return 0;
}

HelloWorld in Assembly:

section .text
global _start
(ld)

_start:

  mov edx,len
  mov ecx,msg
  mov ebx,1
  mov eax,4
  int 0x80
  
  mov eax,1
  int 0x80

section .data

msg db 'Hello, World!',0xa
len equ $ - msg

HelloWorld in Python:

print "Hello World!"