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gzip: Inflate float array in java

I am trying to figure out a way to inflate/deflate an array of floats in java.
My code to deflate looks like this, which seems to work fine.
List<Float> floats = ...;
ByteArrayOutputStream baos = new ByteArrayOutputStream();
GZIPOutputStream gzipOut = new GZIPOutputStream(baos);
ObjectOutputStream objectOut = new ObjectOutputStream(gzipOut);
objectOut.writeObject(floats.toArray(new Float[0]));
return baos.toByteArray();
I am having issues with inflating the byte array again back to a float[] array.
Below is one of my attempts, which fails (it even generates NaN floats)
byte[] bytes =....
ByteArrayInputStream bais = new ByteArrayInputStream(bytes);
GZIPInputStream gzipIn = new GZIPInputStream(bais);
ObjectInputStream objectIn = new ObjectInputStream(gzipIn);
List<Float> floats = new ArrayList<>()
byte[] buffer = new byte[4]
while (gzipIn.read(buffer) >= 0) {
Float f = ByteBuffer.wrap(buffer).float
floats.add(f)
}
return floats
I am be able to use any other classes - I just am not able to block as this would be running inside a non blocking event driven server.

You're using different calls - you're calling writeObject in the writing part, then assuming that you can just read 4 bytes at a time in the reading part.
Why not just use:
Float[] floats = (Float[]) objectIn.readObject();
? That would match your writing code. You can then wrap the array in a list if you want to.

ByteArrayOutputStream.toString() generating extra characters

I have the following code:
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int size = 4096;
byte[] bytes = new byte[size];
while (is.read(bytes, 0, size) != -1)
{
baos.write(bytes);
baos.flush();
}
When I do:
String s = baos.toString();
I get \u0000-s appended to my string. So, if my character data is only X bytes out of Y, the Y-Z will get prefilled with \u0000 making it impossible to check for equals. What am I doing wrong here? How should I be converting the bytes to a String in this case?

The entire array (all 4096 bytes) is be written to the output - arrays have no idea of how much "useful data" they contain!
Store how much was read into a variable (InputStream.read returns a useful number) and specify that to the appropriate OutputStream.write overload to only write a portion (that which contains the useful data) of the array.
While the above change should "fix" the problem, it is generally recommended to use the string<->byte[] conversion forms that take in an explicit character set.

You should only be writing as much data as you are reading in each time through the loop:
ByteArrayOutputStream baos = new ByteArrayOutputStream();
int size;
byte[] bytes = new byte[4096];
while (size = is.read(bytes, 0, bytes.length) != -1)
{
baos.write(bytes, 0, size);
}
baos.flush();
String s = baos.toString();
You might consider specifying a specific character set for converting the bytes to a String. The no-arg toString() method uses the platform default encoding.

new String(baos.toByteArray(), 0, strLen, encoding)

Create a ArrayList of byte Array in Android

I want to read bytes from httpresponse coming from server continuosly into an array.
I'm creating a byte array with a maximum size of 2048.
So, I wanted to create a dynamically increasing array and I found that ArrayList is the solution.
How can i overcome this solution?
Any help would be appreciated lot

You can use a ByteArrayOutputStream to accumulate the bytes as you read them from the server. I would not use an ArrayList<Byte> because it requires boxing every byte value in a Byte.
When you want to access the bytes that have been accumulated, just call toByteArray() on the ByteArrayOutputStream.

You can have an array of byte like:
List<Byte> arrays = new ArrayList<Byte>();
To convert it back to arrays
Byte[] soundBytes = arrays.toArray(new Byte[arrays.size()]);
- You can also use ByteArrayInputStream and ByteArrayOutputStream.
Eg:
InputStream inputStream = socket.getInputStream();
// read from the stream
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] content = new byte[ 2048 ];
int bytesRead = -1;
while( ( bytesRead = inputStream.read( content ) ) != -1 ) {
baos.write( content, 0, bytesRead );
} // while
// now, as you have baos in hand, I don't think you still need a bais instance
// but, to make it complete,
// now you can generate byte array input stream as below
ByteArrayInputStream bais = new ByteArrayInputStream( baos.toByteArray() );

Saving short[] in java (android) with low cpu and space

while streaming music i'm getting pcm data as type short[] and i want to save it to file in my android device so i can play it again later (using AudioTrack). i wan't the store of the music to be efficent in memory and cpu.
how to save short[] to file cause i dont see any function in.write(short[])?
how can i decrease the space\cpu for saving this file?

Wrap your FileOutputStream with DataOutputStream:
DataOutputStream doStream = new DataOutputStream(new BufferedOutputStream(fileOutputStream));
doStream.writeInt(numberArray.length); //Save size
for (int i=0;i<numberArray.length;i++) {
doStream.writeShort(numberArray[i]); //Save each number
}
Same way for reading it back:
DataInputStream diStream = new DataInputStream(new BufferedInputStream(fileInputStream));
int size = diStream.readInt(); //Read size
short[] data = new short[size]; //Create new array with required length
for (int i=0;i<size;i++) {
data[i] = diStream.readShort(); //Read each number
}

Without any encoding to MP3 or similar you can always do like this.
short[] sound = ...;
ByteBuffer byteMyShorts = ByteBuffer.allocate(sound.length * 2);
ShortBuffer shortBytes = byteMyShorts.asShortBuffer();
shortBytes.put(sound);
byteMyShorts.flip();
// byteMyShorts.array() now contains your short[] array as an
// array of bytes.

FileInputStream to byte array in Android application

I have a FileInputStream created using Context.openFileInput(). I now want to convert the file into a byte array.
Unfortunately, I can't determine the size of the byte array required for FileInputStream.read(byte[]). The available() method doesn't work, and I can't create a File to check it's length using the specific pathname, probably because the path is inaccessible to non-root users.
I read about ByteArrayOutputStream, and it seems to dynamically adjust the byte array size to fit, but I can't get how to read from the FileInputStream to write to the ByteArrayOutputStream.

This should work.
InputStream is = Context.openFileInput(someFileName);
ByteArrayOutputStream bos = new ByteArrayOutputStream();
byte[] b = new byte[1024];
while ((int bytesRead = is.read(b)) != -1) {
bos.write(b, 0, bytesRead);
}
byte[] bytes = bos.toByteArray();

This is the easiest way
FileInputStream fis = openFileInput(fileName);
byte[] buffer = new byte[(int) fis.getChannel().size()];
fis.read(buffer);

You can pre-allocate the byte array using
int size = context.getFileStreamPath(filename).length();
This way, you will avoid allocating memory chunks every time your ByteArrayOutputStream fills up.

For the method to work on any device and aplication you just need to replace:
InputStream is = Context.getContentResolver().openInputStream(yourFileURi);
This way you can encode external files as well.