We Keep Coding

Caused by: java.lang.StringIndexOutOfBoundsException: length=7; index=7 Android java

Hi i use function to hex string to byte array and it gives me this error sometimes it works some times it gives error
Caused by: java.lang.StringIndexOutOfBoundsException: length=7;index=7 > at java.lang.String.indexAndLength(String.java:500)
at java.lang.String.charAt(String.java:494)
public static byte[] hexStringToByteArray(String s) {
int len = s.length();
byte[] data = new byte[len/2];
for(int i = 0; i < len; i+=2){
data[i/2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16));
}
return data;
}
error comes in this code and
why it works most of the time and only sometimes it makes application force close,can anybody fix this so that it can work always
i use this function above to make crc32 checsum to bytearray
here is the function i use to get crc32 checsum
private String chesum() {
String fileName = "file.bin";
try {
CheckedInputStream cis = null;
try {
// Compute CRC32 checksum
cis = new CheckedInputStream(
new FileInputStream(fileName), new CRC32());
} catch (FileNotFoundException e) {
System.err.println("File not found.");
}
byte[] buf = new byte[128];
while(cis.read(buf) >= 0) {
}
long checksum = cis.getChecksum().getValue();
String ss = Long.toHexString(checksum);
cis.close();
return ss;
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
after this method i call hexstringtobytearray function

for(int i = 0; i < len-1 ; i+=2){
data[i/2] = (byte) ((Character.digit(s.charAt(i), 16) << 4) + Character.digit(s.charAt(i+1), 16));
}
Change the condition len to len -1

Successfully implemented threading, but I cannot figure out how to write results to file

So, I have the program doing what I want. Using threading to encrypt the passwords has turned a 15 minute task into a 2 minute task. However, I cannot seem to figure out how to write the encrypted passwords to a file. I figured I would have every thread store its result in an array and then I planned on writing the contents of the array out to a file to a file. This doesn't seem to be working at all and I'm not sure why.
I know the code if very sloppy, but I'm just trying to get a working solution before I try to pretty things up.
Thanks!
import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.util.Arrays;
import java.lang.Thread;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
class encryptThread extends Thread {
private Thread t;
private String threadName;
private long[] password_aes;
private String uh = "";
private static final char[] CA = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".toCharArray();
private static final int[] IA = new int[256];
private int j = 0;
static {
Arrays.fill(IA, -1);
for (int i = 0, iS = CA.length; i < iS; i++)
IA[CA[i]] = i;
IA['='] = 0;
}
encryptThread( String name, int i){
threadName = name;
j = i;
}
public void run() {
String finalString = "";
String[] parts = threadName.split(":");
password_aes = prepare_key_pw(parts[1]);
uh = stringhash(parts[0], password_aes);
finalString = (parts[0] + ":" + parts[1] + ":" + uh + "\n");
//System.out.println(finalString);
PassArray.passwordArray[j] = finalString;
if (j == 176) {
for (int x = 0; x < 500; x++) {
System.out.println(PassArray.passwordArray[x]);
}
}
}
public void start ()
{
System.out.println("Starting " + threadName );
if (t == null)
{
t = new Thread (this, threadName);
t.start ();
}
}
public static long[] str_to_a32(String string) {
if (string.length() % 4 != 0) {
string += new String(new char[4 - string.length() % 4]);
}
long[] data = new long[string.length() / 4];
byte[] part = new byte[8];
for (int k = 0, i = 0; i < string.length(); i += 4, k++) {
String sequence = string.substring(i, i + 4);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
try {
baos.write(sequence.getBytes("ISO-8859-1"));
System.arraycopy(baos.toByteArray(), 0, part, 4, 4);
ByteBuffer bb = ByteBuffer.wrap(part);
data[k] = bb.getLong();
} catch (IOException e) {
data[k] = 0;
}
}
return data;
}
public static String a32_to_str(long[] data) {
byte[] part = null;
StringBuilder builder = new StringBuilder();
ByteBuffer bb = ByteBuffer.allocate(8);
for (int i = 0; i < data.length; i++) {
bb.putLong(data[i]);
part = Arrays.copyOfRange(bb.array(), 4, 8);
bb.clear();
ByteArrayInputStream bais = new ByteArrayInputStream(part);
while (bais.available() > 0) {
builder.append((char) bais.read());
}
}
return builder.toString();
}
public static byte[] aes_cbc_encrypt(byte[] data, byte[] key) {
String iv = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
IvParameterSpec ivSpec = new IvParameterSpec(iv.getBytes());
byte[] output = null;
try {
SecretKeySpec keySpec = new SecretKeySpec(key, "AES");
Cipher cipher = Cipher.getInstance("AES/CBC/NOPADDING");
cipher.init(Cipher.ENCRYPT_MODE, keySpec, ivSpec);
output = cipher.doFinal(data);
} catch (Exception e) {
e.printStackTrace();
}
return output;
}
public static long[] aes_cbc_encrypt_a32(long[] idata, long[] ikey) {
try {
byte[] data = a32_to_str(idata).getBytes("ISO-8859-1");
byte[] key = a32_to_str(ikey).getBytes("ISO-8859-1");
byte[] encrypt = aes_cbc_encrypt(data, key);
return str_to_a32(new String(encrypt, "ISO-8859-1"));
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
return new long[0];
}
public static String base64_url_encode(String data) {
try {
data = new String(base64_url_encode_byte((data.getBytes("ISO-8859-1")),true), "ISO-8859-1");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
data = data.replaceAll("\\+", "-");
data = data.replaceAll("/", "_");
data = data.replaceAll("=", "");
return data;
}
public static String a32_to_base64(long[] a) {
return base64_url_encode(a32_to_str(a));
}
public static String stringhash(String email, long[] aeskey) {
long[] s32 = str_to_a32(email);
long[] h32 = {0, 0, 0, 0};
for (int i = 0; i < s32.length; i++) {
h32[i % 4] ^= s32[i];
}
for (int r = 0; r < 0x4000; r++) {
h32 = aes_cbc_encrypt_a32(h32, aeskey);
}
long[] h32Part = new long[2];
h32Part[0] = h32[0];
h32Part[1] = h32[2];
return a32_to_base64(h32Part);
}
public static long[] prepare_key(long[] password) {
long[] pkey = {0x93C467E3, 0x7DB0C7A4, 0xD1BE3F81, 0x0152CB56};
for (int r = 0; r < 0x10000; r++) {
for (int j = 0; j < password.length; j += 4) {
long[] key = {0, 0, 0, 0};
for (int i = 0; i < 4; i++) {
if (i + j < password.length) {
key[i] = password[i + j];
}
}
pkey = aes_cbc_encrypt_a32(pkey, key);
}
}
return pkey;}
public static long[] prepare_key_pw(String password) {
return prepare_key(str_to_a32(password));
}
public final static byte[] base64_url_encode_byte(byte[] sArr, boolean lineSep){
// Check special case
int sLen = sArr != null ? sArr.length : 0;
if (sLen == 0)
return new byte[0];
int eLen = (sLen / 3) * 3; // Length of even 24-bits.
int cCnt = ((sLen - 1) / 3 + 1) << 2; // Returned character count
int dLen = cCnt + (lineSep ? (cCnt - 1) / 76 << 1 : 0); // Length of returned array
byte[] dArr = new byte[dLen];
// Encode even 24-bits
for (int s = 0, d = 0, cc = 0; s < eLen;) {
// Copy next three bytes into lower 24 bits of int, paying attension to sign.
int i = (sArr[s++] & 0xff) << 16 | (sArr[s++] & 0xff) << 8 | (sArr[s++] & 0xff);
// Encode the int into four chars
dArr[d++] = (byte) CA[(i >>> 18) & 0x3f];
dArr[d++] = (byte) CA[(i >>> 12) & 0x3f];
dArr[d++] = (byte) CA[(i >>> 6) & 0x3f];
dArr[d++] = (byte) CA[i & 0x3f];
// Add optional line separator
if (lineSep && ++cc == 19 && d < dLen - 2) {
dArr[d++] = '\r';
dArr[d++] = '\n';
cc = 0;
}
}
// Pad and encode last bits if source isn't an even 24 bits.
int left = sLen - eLen; // 0 - 2.
if (left > 0) {
// Prepare the int
int i = ((sArr[eLen] & 0xff) << 10) | (left == 2 ? ((sArr[sLen - 1] & 0xff) << 2) : 0);
// Set last four chars
dArr[dLen - 4] = (byte) CA[i >> 12];
dArr[dLen - 3] = (byte) CA[(i >>> 6) & 0x3f];
dArr[dLen - 2] = left == 2 ? (byte) CA[i & 0x3f] : (byte) '=';
dArr[dLen - 1] = '=';
}
return dArr;
}
}
public class TestThread {
final static String OUTPUT_FILE_NAME = "C:\\combo_encrypted.txt";
public static void main(String args[]) throws IOException, Throwable {
for (int f = 0; f < 500; f++){
PassArray.passwordArray[f] = "haddy ma'am";
}
File file1 = new File("File1.txt");
File file2 = new File("File2.txt");
File file3 = new File("File3.txt");
File file4 = new File("File4.txt");
FileInputStream fis1 = null;
FileInputStream fis2 = null;
FileInputStream fis3 = null;
FileInputStream fis4 = null;
BufferedInputStream bis1 = null;
BufferedInputStream bis2 = null;
BufferedInputStream bis3 = null;
BufferedInputStream bis4 = null;
DataInputStream dis1 = null;
DataInputStream dis2 = null;
DataInputStream dis3 = null;
DataInputStream dis4 = null;
fis1 = new FileInputStream(file1);
fis2 = new FileInputStream(file2);
fis3 = new FileInputStream(file3);
fis4 = new FileInputStream(file4);
bis1 = new BufferedInputStream(fis1);
bis2 = new BufferedInputStream(fis2);
bis3 = new BufferedInputStream(fis3);
bis4 = new BufferedInputStream(fis4);
dis1 = new DataInputStream(bis1);
dis2 = new DataInputStream(bis2);
dis3 = new DataInputStream(bis3);
dis4 = new DataInputStream(bis4);
int i = 0;
while ( (dis4.available() != 0) ) {
encryptThread[] threadList = new encryptThread[4];
String combo1 = dis1.readLine();
String combo2 = dis2.readLine();
String combo3 = dis3.readLine();
String combo4 = dis4.readLine();
threadList[0] = new encryptThread(combo1, i);
threadList[1] = new encryptThread(combo2, i);
threadList[2] = new encryptThread(combo3, i);
threadList[3] = new encryptThread(combo4, i);
threadList[0].start();
threadList[1].start();
threadList[2].start();
threadList[3].start();
/*
RunnableDemo R1 = new RunnableDemo(combo1, array1, i);
RunnableDemo R2 = new RunnableDemo(combo2, array2, i);
RunnableDemo R3 = new RunnableDemo(combo3, array3, i);
RunnableDemo R4 = new RunnableDemo(combo4, array4, i);
R1.start();
R2.start();
R3.start();
R4.start();
*/
i++;
}
fis1.close();
fis2.close();
fis3.close();
fis4.close();
bis1.close();
bis2.close();
bis3.close();
bis4.close();
dis1.close();
dis2.close();
dis3.close();
dis4.close();
System.out.println(PassArray.passwordArray[5]);
}
}
class PassArray {
public static String[] passwordArray = new String[500];
}

there's a problem here where you are passing this into new Thread(). Maybe the Thread API supports it, but I don't think it's very standard.
public void start ()
{
System.out.println("Starting " + threadName );
if (t == null)
{
t = new Thread (this, threadName);
t.start ();
}
}
as one of the commenters pointed out:
class encryptThread extends Thread
should become
class EncryptThread implements Runnable
then you do
new Thread(new EncryptThread()).start();
when you pass an instance of a class that implements Runnable, or in shorter terms, an instance of Runnable (they are the same) into the Thread constructor, then when you call .start() it actually kicks off in the .run() method of the Runnable instance.

Try to add the following codes:
PrintWriter file = new PrintWriter(new BufferedWriter(new FileWriter(OUTPUT_FILE_NAME, true)));
file.println(finalString);file.close();
...right before the line of code PassArray.passwordArray[j] = finalString; in your thread.
Edit: Remove the previous codes from the main thread.

Replace nio sockets to exec'ed software for binary protocol

I have to make an abstaction in my software - replace direct unblockable NIO sockets ( client/server ) to software abstraction.
For example, instead of connecting via tcp client would exec openssl s_client -connect xxx.xxx.xxx.xxx . I have written a little demo, and it even works. Sometimes :(
The first trouble is that Process's streams can't be used with Selector, so I can't replace socketchannel with any other type of channel, so I have to read/write without any chance to avoid blocking.
The second one is that a protocol is a duplex binary file-transfer protocol ( binkp ), so process's buffered streams are unusabe. I've tried to avoid that converting in/out data to base64 and it works, but also sometimes.
I can't understant why it works or not sometimes. I put a piece of test code below. The first word is frame's length, but first bit is ignored. Please, tell me your guesses. Thanks.
public class BufferedSocketBase64 {
static class InToOut implements Runnable {
InputStream is;
OutputStream os;
boolean direction; //
public InToOut(InputStream is, OutputStream os, boolean direction) {
super();
this.is = is;
this.os = os;
this.direction = direction;
}
#Override
public void run() {
System.out.println(Thread.currentThread().getId() + " start "
+ ((direction) ? "encode from to" : "decode from to"));
boolean eof = false;
while (true) {
if (direction) {
// encode to base64 data
try {
int[] head = new int[2];
for (int i = 0; i < 2; i++) {
head[i] = is.read();
}
int len = (head[0] & 0xff << 8 | head[1] & 0xff) & 0x7FFF;
byte[] buf = new byte[len + 2];
buf[0] = (byte) (head[0] & 0xff);
buf[1] = (byte) (head[1] & 0xff);
for (int i = 2; i < len; i++) {
buf[i] = (byte) (is.read() & 0xff);
}
System.out.println(Thread.currentThread()
.getId() + " << " + new String(buf));
if (len > 0) {
String send = Base64Util.encode(buf, len);
send += "\n";
os.write(send.getBytes());
os.flush();
}
} catch (IOException e) {
eof = true;
}
} else { // decode from base64
try {
StringBuilder sb = new StringBuilder(1024);
byte c = 0x0a;
do {
c = (byte) is.read();
if (c >= 0 && c != 0x0a) {
sb.append(new String(new byte[] { c }));
}
} while (c != 0x0a && c >= 0);
if (sb.length() != 0) {
try {
byte[] buf = Base64Util.decode(sb.toString());
System.out.println(Thread.currentThread()
.getId() + " >> " + buf.length);
os.write(buf);
os.flush();
} catch (StringIndexOutOfBoundsException e) {
System.out
.println(Thread.currentThread().getId()
+ " error on " + sb.toString());
}
}
} catch (IOException e) {
eof = true;
}
}
if (eof) {
System.out.println(Thread.currentThread().getId() + " EOF");
break;
}
}
try {
is.close();
os.close();
} catch (IOException e) {
}
}
}
public static void main(String[] args) throws Exception {
Process proc2 = Runtime.getRuntime().exec("nc -l -p 2020");
Process proc1 = Runtime.getRuntime().exec("nc 127.0.0.1 2020");
Socket sock1 = new Socket();
sock1.connect(new InetSocketAddress("127.0.0.1", 24554), 30);
Socket sock2 = new Socket();
sock2.connect(new InetSocketAddress("127.0.0.1", 24557), 30);
new Thread(new InToOut(sock1.getInputStream(), proc1.getOutputStream(),
true)).start();
new Thread(new InToOut(proc1.getInputStream(), sock1.getOutputStream(),
false)).start();
new Thread(new InToOut(sock2.getInputStream(), proc2.getOutputStream(),
true)).start();
new Thread(new InToOut(proc2.getInputStream(), sock2.getOutputStream(),
false)).start();
}
UPDATED:
I've found right way. I uses syncchronized queries for each stream and synchronized threads to fill or erase that queries. All threads mutually blocks themselves. And it works! :)
Sorry for bother.

I've found right way. I uses syncchronized queries for each stream and synchronized threads to fill or erase that queries. All threads mutually blocks themselves. And it works! :) Sorry for bother.

Java serial port write/send ASCII data

My problem is that I need to control mobile robot E-puck via Bluetooth in Java, by sending it commands like "D,100,100" to set speed, "E" to get speed, and etc. I have some code:
String command = "D,100,100";
OutputStream mOutputToPort = serialPort.getOutputStream();
mOutputToPort.write(command.getBytes());
So with this method write I can only send byte[] data, but my robot won't understand that.
For example previously I have been using this commands on Matlab like that:
s = serial('COM45');
fopen(s);
fprintf(s,'D,100,100','async');
Or on program Putty type only:
D,100,100 `enter`
Additional info:
I've also figured out, that Matlab has another solution for same thing.
s = serial('COM45');
fopen(s);
data=[typecast(int8('-D'),'int8') typecast(int16(500),'int8') typecast(int16(500),'int8')];
In this case:
data = [ -68 -12 1 -12 1];
fwrite(s,data,'int8','async');
Wouldn't it be the same in Java:
byte data[] = new byte[5];
data[0] = -'D';
data[1] = (byte)(500 & 0xFF);
data[2] = (byte)(500 >> 8);
data[3] = (byte)(500 & 0xFF);
data[4] = (byte)(500>> 8);
And then:
OutputStream mOutputToPort = serialPort.getOutputStream();
mOutputToPort.write(data);
mOutputToPort.flush();

Main details in code comments. Now you can change wheel speed by typing in command window D,1000,-500 and hitting enter.
public class serialRobot {
public static void main(String[] s) {
SerialPort serialPort = null;
try {
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier("COM71");
if (portIdentifier.isCurrentlyOwned()) {
System.out.println("Port in use!");
} else {
System.out.println(portIdentifier.getName());
serialPort = (SerialPort) portIdentifier.open(
"ListPortClass", 300);
int b = serialPort.getBaudRate();
System.out.println(Integer.toString(b));
serialPort.setSerialPortParams(115200, SerialPort.DATABITS_8,
SerialPort.STOPBITS_1, SerialPort.PARITY_NONE);
serialPort.setInputBufferSize(65536);
serialPort.setOutputBufferSize(4096);
System.out.println("Opened " + portIdentifier.getName());
OutputStream mOutputToPort = serialPort.getOutputStream();
InputStream mInputFromPort = serialPort.getInputStream();
PerpetualThread t = readAndPrint(mInputFromPort);
inputAndSend(mOutputToPort);
t.stopRunning();
mOutputToPort.close();
mInputFromPort.close();
}
} catch (IOException ex) {
System.out.println("IOException : " + ex.getMessage());
} catch (UnsupportedCommOperationException ex) {
System.out.println("UnsupportedCommOperationException : " + ex.getMessage());
} catch (NoSuchPortException ex) {
System.out.println("NoSuchPortException : " + ex.getMessage());
} catch (PortInUseException ex) {
System.out.println("PortInUseException : " + ex.getMessage());
} finally {
if(serialPort != null) {
serialPort.close();
}
}
}
private static PerpetualThread readAndPrint(InputStream in) {
final BufferedInputStream b = new BufferedInputStream(in);
PerpetualThread thread = new PerpetualThread() {
#Override
public void run() {
byte[] data = new byte[16];
int len = 0;
for(;isRunning();) {
try {
len = b.read(data);
} catch (IOException e) {
e.printStackTrace();
}
if(len > 0) {
System.out.print(new String(data, 0, len));
}
}
}
};
thread.start();
return thread;
}
private static void inputAndSend(OutputStream out) {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
int k = 0;
for(;;) {
String komanda;
try {
komanda = in.readLine();
} catch (IOException e) {
e.printStackTrace();
return;
}
komanda = komanda.trim();
if(komanda.equalsIgnoreCase("end")) return;
byte komandaSiust[] = proces(komanda); //Command we send after first
//connection, it's byte array where 0 member is the letter that describes type of command, next two members
// is about left wheel speed, and the last two - right wheel speed.
try {
if(k == 0){
String siunc = "P,0,0\n"; // This command must be sent first time, when robot is connected, otherwise other commands won't work
ByteBuffer bb = ByteBuffer.wrap(siunc.getBytes("UTF-8"));
bb.order(ByteOrder.LITTLE_ENDIAN);
out.write(bb.array());
out.flush();
}else{
ByteBuffer bb = ByteBuffer.wrap(komandaSiust);
bb.order(ByteOrder.LITTLE_ENDIAN);
out.write(bb.array());
out.flush();
}
k++;
} catch (IOException e) {
e.printStackTrace();
return;
}
}
}
private static byte[] proces(String tekstas){
tekstas = tekstas.trim();
char[] charArray = tekstas.toCharArray();
byte kodas1[];
int fComa = tekstas.indexOf(',', 1);
int sComa = tekstas.indexOf(',', 2);
int matavimas = charArray.length;
int skir1 = sComa - fComa - 1;
int skir2 = matavimas - sComa -1;
char leftSpeed[] = new char[skir1];
for(int i = 0; i < skir1; i++){
leftSpeed[i] = charArray[fComa + i + 1];
}
char rightSpeed[] = new char[skir2];
for(int i = 0; i < skir2; i++){
rightSpeed[i] = charArray[sComa + i + 1];
}
String right = String.valueOf(rightSpeed);
String left = String.valueOf(leftSpeed);
int val1 = Integer.parseInt(left);
int val2 = Integer.parseInt(right);
kodas1 = new byte[5];
kodas1[0] = (byte)-charArray[0];
kodas1[1] = (byte)(val1 & 0xFF);
kodas1[2] = (byte)(val1 >> 8);
kodas1[3] = (byte)(val2 & 0xFF);
kodas1[4] = (byte)(val2 >> 8);
return kodas1;
}
private static class PerpetualThread extends Thread {
private boolean isRunning = true;
public boolean isRunning() { return isRunning; }
public void stopRunning() {
isRunning = false;
this.interrupt();
}
}
}

According to the documentation, you need to call setSerialPortParams(int baudrate, int dataBits, int stopBits, int parity) on your serial port.

Merging two WAVE files on Android (concatenate)

I have been trying to merge two WAVE files on Android for quite some time now but really can't seem to get it working properly.
Everything looks fine, the files are read, and written to the output file which is also readable at a later stage and has the file size I would expect to see.
The problems occur right after the app has finished merging. This message will show in the log: Error occured in updateListener, recording is aborted which is a message from extAudioRecorder and appears when the OnRecordPositionUpdateListener reaches the catch clause (the Exception has the following detailMessage: write failed: EBADF (Bad file number)). This does not seem to break anything so I'm not too worried about this.
The real problem arises when I try to create a MediaPlayer and call the setDataSource(String path) on the MediaPlayer instance. Whenever I do this with a merged file the following error message will show in the log: Unable to to create media player (the IOException that is thrown contains the following detailMessage: setDataSourceFD failed.: status=0x80000000). Note that the first time the file will play perfectly fine (this first file was not made by the combineWaveFiles() method). That Error message appears to indicate that the audio file's format is incorrect and/or can't be read by the MediaPlayer.
My question is if anyone sees any real problems with the code below (I know it's sub-optimal in many ways but I prefer to get it to work first then worry about performance).
public static String MergeRecordings(String cumulativeFile, String recordFile, int sampleRate, int bpp, int bufferSize, int channels) {
if (cumulativeFile == null) {
return recordFile;
} else if (recordFile == null) {
return cumulativeFile;
}
String outputFile = FileUtils.getFilePath(null, MDSettings.shared().getMainActivity());
FileUtils.combineWaveFiles(cumulativeFile, recordFile, outputFile, sampleRate, bpp, bufferSize, channels);
//FileUtils.removeFile(cumulativeFile);
//FileUtils.removeFile(recordFile);
return outputFile;
}
//creates a new file containing file1 + file2 stuck together as such.
private static void combineWaveFiles(String file1, String file2, String outputFile, int sampleRate, int bpp, int bufferSize, int channels) {
FileInputStream in1 = null, in2 = null;
FileOutputStream out = null;
long longSampleRate = sampleRate;
long byteRate = sampleRate * channels * bpp / 8;
byte[] data;
try {
try {
in1 = new FileInputStream(file1);
} catch (Exception e) { }
try {
in2 = new FileInputStream(file2);
} catch (FileNotFoundException e) { }
out = new FileOutputStream(outputFile);
long file1Size = 0;
long file2Size = 0;
if (in1 != null) { file1Size = in1.getChannel().size() - 44; }
if (in2 != null) { file2Size = in2.getChannel().size() - 44; }
long totalAudioLen = file1Size + file2Size;
long totalDataLen = totalAudioLen + 36;
FileUtils.writeWaveFileHeader(out, totalAudioLen, totalDataLen, longSampleRate, channels, byteRate, bpp);
if (in1 != null) {
in1.skip(44);
data = new byte[bufferSize];
if (file1Size < bufferSize) {
data = new byte[(int)file1Size];
}
while (in1.read(data) != -1) {
out.write(data);
file1Size -= bufferSize;
if (file1Size <= 0) {
break;
} else if (file1Size < bufferSize) {
data = new byte[(int)file1Size];
}
}
}
if (in2 != null) {
in2.skip(44);
data = new byte[bufferSize];
if (file2Size < bufferSize) {
data = new byte[(int)file2Size];
}
while (in2.read(data) != -1) {
out.write(data);
file2Size -= bufferSize;
if (file2Size <= 0) {
break;
} else if (file2Size < bufferSize) {
data = new byte[(int)file2Size];
}
}
}
out.close();
if (in1 != null) { in1.close(); }
if (in2 != null) { in2.close(); }
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
private static void writeWaveFileHeader(FileOutputStream out, long totalAudioLen, long totalDataLen, long longSampleRate, int channels, long byteRate, int bpp)
throws IOException {
byte[] header = new byte[44];
header[0] = 'R';
header[1] = 'I';
header[2] = 'F';
header[3] = 'F';
header[4] = (byte)(totalDataLen & 0xff);
header[5] = (byte)((totalDataLen >> 8) & 0xff);
header[6] = (byte)((totalDataLen >> 16) & 0xff);
header[7] = (byte)((totalDataLen >> 24) & 0xff);
header[8] = 'W';
header[9] = 'A';
header[10] = 'V';
header[11] = 'E';
header[12] = 'f';
header[13] = 'm';
header[14] = 't';
header[15] = ' ';
header[16] = 16;
header[17] = 0;
header[18] = 0;
header[19] = 0;
header[20] = 1;
header[21] = 0;
header[22] = (byte) channels;
header[23] = 0;
header[24] = (byte)(longSampleRate & 0xff);
header[25] = (byte)((longSampleRate >> 8) & 0xff);
header[26] = (byte)((longSampleRate >> 16) & 0xff);
header[27] = (byte)((longSampleRate >> 24) & 0xff);
header[28] = (byte)(byteRate & 0xff);
header[29] = (byte)((byteRate >> 8) & 0xff);
header[30] = (byte)((byteRate >> 16) & 0xff);
header[31] = (byte)((byteRate >> 24) & 0xff);
header[32] = (byte)(channels * bpp); //(2 * 16 / 8);
header[33] = 0;
header[34] = (byte)bpp;
header[35] = 0;
header[36] = 'd';
header[37] = 'a';
header[38] = 't';
header[39] = 'a';
header[40] = (byte)(totalAudioLen & 0xff);
header[41] = (byte)((totalAudioLen >> 8) & 0xff);
header[42] = (byte)((totalAudioLen >> 16) & 0xff);
header[43] = (byte)((totalAudioLen >> 24) & 0xff);
out.write(header, 0, 44);
}
Large parts of this code are taken from this answer.

i do this exactly in my android app. Instead of two, i merge multiple files based on users selection. I use AsyncTask to merge the samples in the background. Take a look at it here. Just filter the section that you need. If you are curious about my app, its called Sound Recorder + Pro, Beside merge i do mix, add echo and amplify samples:
#Override
protected Void doInBackground(Void... params) {
isProcessingOn=true;
try {
DataOutputStream amplifyOutputStream = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(Environment.getExternalStorageDirectory() + "/Soundrecpluspro/" + year +"-"+ month +"-"+ date +"-"+ hour+"-" + min +"-"+ sec+"ME.wav")));
DataInputStream[] mergeFilesStream = new DataInputStream[selection.size()];
long[] sizes=new long[selection.size()];
for(int i=0; i<selection.size(); i++) {
File file = new File(Environment.getExternalStorageDirectory() + "/Soundrecpluspro/" +selection.get(i));
sizes[i] = (file.length()-44)/2;
}
for(int i =0; i<selection.size(); i++) {
mergeFilesStream[i] =new DataInputStream(new BufferedInputStream(new FileInputStream(Environment.getExternalStorageDirectory() + "/Soundrecpluspro/" +selection.get(i))));
if(i == selection.size()-1) {
mergeFilesStream[i].skip(24);
byte[] sampleRt = new byte[4];
mergeFilesStream[i].read(sampleRt);
ByteBuffer bbInt = ByteBuffer.wrap(sampleRt).order(ByteOrder.LITTLE_ENDIAN);
RECORDER_SAMPLERATE = bbInt.getInt();
mergeFilesStream[i].skip(16);
}
else {
mergeFilesStream[i].skip(44);
}
}
for(int b=0; b<selection.size(); b++) {
for(int i=0; i<(int)sizes[b]; i++) {
byte[] dataBytes = new byte[2];
try {
dataBytes[0] = mergeFilesStream[b].readByte();
dataBytes[1] = mergeFilesStream[b].readByte();
}
catch (EOFException e) {
amplifyOutputStream.close();
}
short dataInShort = ByteBuffer.wrap(dataBytes).order(ByteOrder.LITTLE_ENDIAN).getShort();
float dataInFloat= (float) dataInShort/37268.0f;
short outputSample = (short)(dataInFloat * 37268.0f);
byte[] dataFin = new byte[2];
dataFin[0] = (byte) (outputSample & 0xff);
dataFin[1] = (byte)((outputSample >> 8) & 0xff);
amplifyOutputStream.write(dataFin, 0 , 2);
}
}
amplifyOutputStream.close();
for(int i=0; i<selection.size(); i++) {
mergeFilesStream[i].close();
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
long size =0;
try {
FileInputStream fileSize = new FileInputStream(Environment.getExternalStorageDirectory() + "/Soundrecpluspro/"+year +"-"+ month +"-"+ date +"-"+ hour+"-" + min +"-"+ sec+"ME.wav");
size = fileSize.getChannel().size();
fileSize.close();
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
final int RECORDER_BPP = 16;
long datasize=size+36;
long byteRate = (RECORDER_BPP * RECORDER_SAMPLERATE)/8;
long longSampleRate = RECORDER_SAMPLERATE;
byte[] header = new byte[44];
header[0] = 'R'; // RIFF/WAVE header
header[1] = 'I';
header[2] = 'F';
header[3] = 'F';
header[4] = (byte) (datasize & 0xff);
header[5] = (byte) ((datasize >> 8) & 0xff);
header[6] = (byte) ((datasize >> 16) & 0xff);
header[7] = (byte) ((datasize >> 24) & 0xff);
header[8] = 'W';
header[9] = 'A';
header[10] = 'V';
header[11] = 'E';
header[12] = 'f'; // 'fmt ' chunk
header[13] = 'm';
header[14] = 't';
header[15] = ' ';
header[16] = 16; // 4 bytes: size of 'fmt ' chunk
header[17] = 0;
header[18] = 0;
header[19] = 0;
header[20] = 1; // format = 1
header[21] = 0;
header[22] = (byte) 1;
header[23] = 0;
header[24] = (byte) (longSampleRate & 0xff);
header[25] = (byte) ((longSampleRate >> 8) & 0xff);
header[26] = (byte) ((longSampleRate >> 16) & 0xff);
header[27] = (byte) ((longSampleRate >> 24) & 0xff);
header[28] = (byte) (byteRate & 0xff);
header[29] = (byte) ((byteRate >> 8) & 0xff);
header[30] = (byte) ((byteRate >> 16) & 0xff);
header[31] = (byte) ((byteRate >> 24) & 0xff);
header[32] = (byte) ((RECORDER_BPP) / 8); // block align
header[33] = 0;
header[34] = RECORDER_BPP; // bits per sample
header[35] = 0;
header[36] = 'd';
header[37] = 'a';
header[38] = 't';
header[39] = 'a';
header[40] = (byte) (size & 0xff);
header[41] = (byte) ((size >> 8) & 0xff);
header[42] = (byte) ((size >> 16) & 0xff);
header[43] = (byte) ((size >> 24) & 0xff);
// out.write(header, 0, 44);
try {
RandomAccessFile rFile = new RandomAccessFile(Environment.getExternalStorageDirectory() + "/Soundrecpluspro/" +year +"-"+ month +"-"+ date +"-"+ hour+"-" + min +"-"+ sec+ "ME.wav", "rw");
rFile.seek(0);
rFile.write(header);
rFile.close();
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}

Try with this code for concatenating the wav files:
public class ConcateSongActivity extends Activity {
Button mbutt;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mbutt = (Button)findViewById(R.id.button_clickme);
mbutt.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View arg0) {
try {
FileInputStream fis1 = new FileInputStream("/sdcard/MJdangerous.wav");
FileInputStream fis2 = new FileInputStream("/sdcard/MJBad.wav");
SequenceInputStream sis = new SequenceInputStream(fis1,fis2);
FileOutputStream fos = new FileOutputStream(new File("/sdcard/MJdangerousMJBad.wav"));
int temp;
try {
while ((temp = sis.read())!= -1){
fos.write(temp);
}
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
});
} }
Note: don't forget to give this permission WRITE_EXTERNAL_STORAGE
other tricks:
This is the methods used to mix 3 sounds together:
private void mixFiles(){
try {
InputStream is1 = getResources().openRawResource(R.raw.test1);
List<Short> music1 = createMusicArray(is1);
InputStream is2 = getResources().openRawResource(R.raw.test2);
List<Short> music2 = createMusicArray(is2);
completeStreams(music1,music2);
short[] music1Array = buildShortArray(music1);
short[] music2Array = buildShortArray(music2);
short[] output = new short[music1Array.length];
for(int i=0; i < output.length; i++){
float samplef1 = music1Array[i] / 32768.0f;
float samplef2 = music2Array[i] / 32768.0f;
float mixed = samplef1 + samplef2;
// reduce the volume a bit:
mixed *= 0.8;
// hard clipping
if (mixed > 1.0f) mixed = 1.0f;
if (mixed < -1.0f) mixed = -1.0f;
short outputSample = (short)(mixed * 32768.0f);
output[i] = outputSample;
}
saveToFile(output);
} catch (NotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
Once we have a PCM mixed sound, it can be transformed in a .wav file so that every player can read it.
/**
* Dealing with big endian streams
* #param byte0
* #param byte1
* #return a shrt with the two bytes swapped
*/
private static short swapBytes(byte byte0, byte byte1){
return (short)((byte1 & 0xff) << 8 | (byte0 & 0xff));
}
/**
* From file to byte[] array
* #param sample
* #param swap should swap bytes?
* #return
* #throws IOException
*/
public static byte[] sampleToByteArray(File sample, boolean swap) throws IOException{
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BufferedInputStream bis = new BufferedInputStream(new FileInputStream(sample));
int BUFFERSIZE = 4096;
byte[] buffer = new byte[BUFFERSIZE];
while(bis.read(buffer) != - 1){
baos.write(buffer);
}
byte[] outputByteArray = baos.toByteArray();
bis.close();
baos.close();
if(swap){
for(int i=0; i < outputByteArray.length - 1; i=i+2){
byte byte0 = outputByteArray[i];
outputByteArray[i] = outputByteArray[i+1];
outputByteArray[i+1] = byte0;
}
}
return outputByteArray;
}
/**
* Read a file and returns its contents as array of shorts
* #param sample the sample file
* #param swap true if we should swap the bytes of short (reading a little-endian file), false otherwise (reading a big-endian file)
* #return
* #throws IOException
*/
public static short[] sampleToShortArray(File sample, boolean swap) throws IOException{
short[] outputArray = new short[(int)sample.length()/2];
byte[] outputByteArray = sampleToByteArray(sample,false);
for(int i=0, j=0; i < outputByteArray.length; i+= 2, j++){
if(swap){
outputArray[j] = swapBytes(outputByteArray[i], outputByteArray[i + 1]);
}
else{
outputArray[j] = swapBytes(outputByteArray[i + 1], outputByteArray[i]);
}
}
return outputArray;
}
public void completeStreams(List<Short> mListShort_1, List<Short> mListShort_2) {
//TODO: check length
int size_a = mListShort_1.size();
int size_b = mListShort_2.size();
if (size_a > size_b){
// adding series of '0'
for (int i = size_b+1; i <= size_a; i++) {
mListShort_2.set(i, (short) 0);
}
} else if (size_a < size_b) {
for (int i = size_a+1; i <= size_b; i++) {
mListShort_1.set(i, (short) 0);
}
} else {
//do nothing
}
}
Credits: nalitzis