Javax.* Cannot Be Imported in My Android App

javax.* cannot be imported in my Android app?

Be aware that when you run an Android app: you don't run/compile it on a standard JVM/JDK, you don't even execute java bytecode. Google choose the java language (or at least a subset of it) as the language to do Android development, but it's only the language.

At the end the compiled java code is not java bytecode, but this is dalvik bytecode. (there is no .class files, but .dex files)

So, when doing Android development: you cannot use the full JavaSE API: you are limited to the API supported by the dalvik VM (available here).

(Note that when you browse this API beware of the version in the top right corner of the page : Added in API level X. It informs you about the Android-API version supporting that class or method)

Android include javax.sound.sampled.*

Android does not support it :(

getting failed to resolve when adding dependency

The problem is not with the dependency you just added but the Android Support library's dependencies. The latest SDK updates move towards using the remote Google Maven repository instead of downloading everything to be available locally. In order to fix dependency resolution problems follow the Adding Support Libraries guide. Really briefly this is what you have to do:

1. Open your project's build.gradle (note that this is not the module's file!)

2. Add the Google Maven repo to the project repositories:

   allprojects {
       repositories {
           jcenter()
           maven {
               url "https://maven.google.com"
           }
       }
   }
   

It's also recommended to add the repo to the buildscript block too, so later on the Gradle plugins can be downloaded from there too:

buildscript {
    repositories {
        jcenter()
        maven {
            url "https://maven.google.com"
        }
    }

Stream Live Android Audio to Server

So I got my problem fixed. The problem was mainly on the receiving side. The receiver takes in the audio stream and pushes it out to the PC's speakers. The resulting voice is still quite laggy and broken but it works none the less. Playing around with the buffer size may improve this.

Edit : you use a thread to read the audio in order the avoid lag. Also, it is better to use a sampling size of 16 000 as it is ok for voice.

Android Code:

package com.example.mictest2;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.UnknownHostException;

import android.app.Activity;
import android.media.AudioFormat;
import android.media.AudioRecord;
import android.media.MediaRecorder;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class Send extends Activity {
private Button startButton,stopButton;

public byte[] buffer;
public static DatagramSocket socket;
private int port=50005;

AudioRecord recorder;

private int sampleRate = 16000 ; // 44100 for music
private int channelConfig = AudioFormat.CHANNEL_CONFIGURATION_MONO;    
private int audioFormat = AudioFormat.ENCODING_PCM_16BIT;       
int minBufSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat);
private boolean status = true;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    startButton = (Button) findViewById (R.id.start_button);
    stopButton = (Button) findViewById (R.id.stop_button);

    startButton.setOnClickListener (startListener);
    stopButton.setOnClickListener (stopListener);

}

private final OnClickListener stopListener = new OnClickListener() {

    @Override
    public void onClick(View arg0) {
                status = false;
                recorder.release();
                Log.d("VS","Recorder released");
    }

};

private final OnClickListener startListener = new OnClickListener() {

    @Override
    public void onClick(View arg0) {
                status = true;
                startStreaming();           
    }

};

public void startStreaming() {

    Thread streamThread = new Thread(new Runnable() {

        @Override
        public void run() {
            try {

                DatagramSocket socket = new DatagramSocket();
                Log.d("VS", "Socket Created");

                byte[] buffer = new byte[minBufSize];

                Log.d("VS","Buffer created of size " + minBufSize);
                DatagramPacket packet;

                final InetAddress destination = InetAddress.getByName("192.168.1.5");
                Log.d("VS", "Address retrieved");

                recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,sampleRate,channelConfig,audioFormat,minBufSize*10);
                Log.d("VS", "Recorder initialized");

                recorder.startRecording();

                while(status == true) {

                    //reading data from MIC into buffer
                    minBufSize = recorder.read(buffer, 0, buffer.length);

                    //putting buffer in the packet
                    packet = new DatagramPacket (buffer,buffer.length,destination,port);

                    socket.send(packet);
                    System.out.println("MinBufferSize: " +minBufSize);

                }

            } catch(UnknownHostException e) {
                Log.e("VS", "UnknownHostException");
            } catch (IOException e) {
                e.printStackTrace();
                Log.e("VS", "IOException");
            } 
        }

    });
    streamThread.start();
 }
 }

Android XML:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="@string/hello_world" />

<Button
    android:id="@+id/start_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/textView1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="130dp"
    android:text="Start" />

<Button
    android:id="@+id/stop_button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/button1"
    android:layout_below="@+id/button1"
    android:layout_marginTop="64dp"
    android:text="Stop" />

</RelativeLayout>

Server code:

package com.datagram;

import java.io.ByteArrayInputStream;
import java.net.DatagramPacket;
import java.net.DatagramSocket;

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.FloatControl;
import javax.sound.sampled.SourceDataLine;

class Server {

AudioInputStream audioInputStream;
static AudioInputStream ais;
static AudioFormat format;
static boolean status = true;
static int port = 50005;
static int sampleRate = 44100;

public static void main(String args[]) throws Exception {

    DatagramSocket serverSocket = new DatagramSocket(50005);

    byte[] receiveData = new byte[1280]; 
    // ( 1280 for 16 000Hz and 3584 for 44 100Hz (use AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioFormat) to get the correct size)

    format = new AudioFormat(sampleRate, 16, 1, true, false);

    while (status == true) {
        DatagramPacket receivePacket = new DatagramPacket(receiveData,
                receiveData.length);

        serverSocket.receive(receivePacket);

        ByteArrayInputStream baiss = new ByteArrayInputStream(
                receivePacket.getData());

        ais = new AudioInputStream(baiss, format, receivePacket.getLength());

        // A thread solve the problem of chunky audio 
        new Thread(new Runnable() {
            @Override
            public void run() {
                toSpeaker(receivePacket.getData());
            }
        }).start();
    }
}

public static void toSpeaker(byte soundbytes[]) {
    try {

        DataLine.Info dataLineInfo = new DataLine.Info(SourceDataLine.class, format);
        SourceDataLine sourceDataLine = (SourceDataLine) AudioSystem.getLine(dataLineInfo);

        sourceDataLine.open(format);

        FloatControl volumeControl = (FloatControl) sourceDataLine.getControl(FloatControl.Type.MASTER_GAIN);
        volumeControl.setValue(100.0f);

        sourceDataLine.start();
        sourceDataLine.open(format);

        sourceDataLine.start();

        System.out.println("format? :" + sourceDataLine.getFormat());

        sourceDataLine.write(soundbytes, 0, soundbytes.length);
        System.out.println(soundbytes.toString());
        sourceDataLine.drain();
        sourceDataLine.close();
    } catch (Exception e) {
        System.out.println("Not working in speakers...");
        e.printStackTrace();
    }
}
}

I hope this helps save someone a few hours of pain :)

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