• Eclipse with android sdk
• Android ndk(Download it from: http://developer.android.com/tools/sdk/ndk/index.html)

package com.alag.firstjni;

public class SquaredWrapper {

    // Declare native method (and make it public to expose it directly)

    public static native int squared(int base);

    

    // Provide additional functionality, that "extends" the native method

    public static int to4(int base)

    {

        int sq = squared(base);

        return squared(sq);

    }

    

    // Load library

    static {

        System.loadLibrary("squared");

    }

}

cd src # change into the source directory

javac -d /tmp/ com/alag/firstjni/SquaredWrapper.java

cd /tmp

javah -jni com.alag.firstjni.SquaredWrapper

/* DO NOT EDIT THIS FILE - it is machine generated */

#include

/* Header for class com_alag_firstjni_SquaredWrapper */

#ifndef _Included_com_alag_firstjni_SquaredWrapper

#define _Included_com_alag_firstjni_SquaredWrapper

#ifdef __cplusplus

extern "C" {

#endif

/*

 * Class:     com_alag_firstjni_SquaredWrapper

 * Method:    squared

 * Signature: (I)I

 */

JNIEXPORT jint JNICALL Java_com_alag_firstjni_SquaredWrapper_squared

  (JNIEnv *, jclass, jint);

#ifdef __cplusplus

}

#endif

#endif

#include "squared.h";

JNIEXPORT jint JNICALL Java_com_alag_firstjni_SquaredWrapper_squared

  (JNIEnv * je, jclass jc, jint base)

{

        return (base*base);

}

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := squared

LOCAL_SRC_FILES := squared.c

include $(BUILD_SHARED_LIBRARY)

cd FirstJni

/path/to/ndk-build # for example: ~/build/android-ndk/android-ndk-r7c/ndk-build

Compile thumb  : squared <= squared.c

SharedLibrary  : libsquared.so

Install        : libsquared.so => libs/armeabi/libsquared.so

package com.alag.firstjni;

import android.os.Bundle;

import android.app.Activity;

import android.util.Log;

import android.view.Menu;

public class MainActivity extends Activity {

          @Override

          protected void onCreate(Bundle savedInstanceState) {

                   super.onCreate(savedInstanceState);

                   setContentView(R.layout.activity_main);

                  

                   int b = 3;

        int a = SquaredWrapper.to4(b);

        Log.i("JNIDemo", String.format("%d->%d", b,a));

          }

          @Override

          public boolean onCreateOptionsMenu(Menu menu) {

                   // Inflate the menu; this adds items to the action bar if it is present.

                   getMenuInflater().inflate(R.menu.main, menu);

                   return true;

          }

}

Hi friends,

Oct 2011, I started my career with android, and it is been one and half years. For Last one year, it is been a dream for me to open developer account in GOOGLE PLAY. But days passed in search/in learning for new idea, concept and bla bla. Now, I can't control my interest to enter into Google Play as a developer, so I planned to publish something. I went through my pass-time work in android; I had code, which I wrote to transfer text in Bluetooth. Of-course, this is school days program. But my interest asked me to give a touch to it and released it in the Google Play. So, I did the same...

BLUE TALK

"Wanna talk in classroom? Wanna chat in meeting hall? Or Wanna share the secret?
Let us help you now @ any place (@ close range).
One easy and smart way to talk, when you can't talk.
Keep talking... keep enjoying..."

This is how I have started my first app in Google play.



It is a basic Bluetooth chat app to communicate with a friend at short range. It will search the discoverable devices in the short range. It will show the list of devices, from which we can select and communicate.

There is Limitation/Requirement in it since it is half done. It supports only when the app in foreground and one-to-one connection only. Give me some time; I'm trying to remove the limitation and requirement in it.

Now this work is motivating to do more and taught me to create a real time work. Hope, your support will also be there :).

Special thanks to Dipta Pandit help me in designing work...
Thanks to my friends for supporting me...
Thanks to Eclipse and Google...

With these 3, OS will understand the input given by us and perform the action to the corresponding input.
 
Example : when we press key 2 in the keyboard... event sequence will be like the below

In ubuntu,  (I wrote a c program to read the input even from device and the output is below)
Event: type 4 (Misc), code 4 (ScanCode), value 458783   [Conveying the event is scancode]
Event: type 1 (Key), code 3 (2), value 1                             [key 2 pressed]
Event: type 0 (Sync), code 0 (Sync), value 0                      [sync event]
Event: type 4 (Misc), code 4 (ScanCode), value 458783    [conveying the event is scancode]
Event: type 1 (Key), code 3 (2), value 0                             [key 2 release]
Event: type 0 (Sync), code 0 (Sync), value 0                      [sync event]

In andriod,
Event: type 1 (Key), code 3 (2), value 1                             [key 2 pressed]
Event: type 0 (Sync), code 0 (Sync), value 0                      [sync event]
Event: type 1 (Key), code 3 (2), value 0                             [key 2 release]
Event: type 0 (Sync), code 0 (Sync), value 0                      [sync event]

This is for pressing the key 2 once... This will be written into the device, OS will read it and perform the actions.

ok now...

getevent : will print the event written into the device.
syntax    : getevent device
example : getevent /dev/input/event0
output    :  In android, it didn't say the scancode... but all the inputs are handled as scancodes. output is,
0001 0003 00000001
0000 0000 00000000
0001 0003 00000000
0000 0000 00000000

sendevent : will allow us to give the input in the terminal.
syntax       : sendevent device type code value.
example    : for writing key 2 into the device.
shell@android:/ # sendevent dev/input/event0 0000 0000 00000000
shell@android:/ # sendevent dev/input/event0 0001 0003 00000001
shell@android:/ # sendevent dev/input/event0 0000 0000 00000000
shell@android:/ # sendevent dev/input/event0 0000 0000 00000000


P.S. : Remember the two points below,

1.  Run it in the android shell.
2.  Should have root permission.