Gzip decompression adds one extra byte ... Why?

Question

I wrote a simple piece of Java code that takes a string, converts it to byte [], and then compresses it using Gzip. He then decompresses the result to return the byte [], which now contains one extra byte of the byte. Why is there a dirt bike here?

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

String testString = "Sample String here";
byte[] originalBytes = testString.getBytes();

ByteArrayOutputStream baos = new ByteArrayOutputStream();
GZIPOutputStream gzos = new GZIPOutputStream(baos);
gzos.write(originalBytes);
gzos.close();

byte[] compressedBytes = baos.toByteArray();

ByteArrayInputStream bais = new ByteArrayInputStream(compressedBytes);
GZIPInputStream gzis = new GZIPInputStream(bais);

ByteArrayOutputStream dbaos = new ByteArrayOutputStream();
while(gzis.available() > 0) {
    dbaos.write(gzis.read());
}
byte[] decompressedBytes = dbaos.toByteArray();
String decompressedString = new String(decompressedBytes);

System.out.println(">>" + decompressedString + "<<");
System.out.println("Size of bytes before: " + originalBytes.length);
System.out.println("Size of bytes after: " + decompressedBytes.length);

}

Conclusion:

>>Sample String here <<
Size of bytes before: 18
Size of bytes after: 19

Can someone tell me why there is a byte for garbage? How can I get rid of it WITHOUT changing the code setting above?

Answer 1

Here you use available(), so you get one extra byte. You should read the stream and check the value less 0. Change it

ByteArrayOutputStream dbaos = new ByteArrayOutputStream();
while(gzis.available() > 0) {
    dbaos.write(gzis.read());
}

-

ByteArrayOutputStream dbaos = new ByteArrayOutputStream();
int b;
while ((b = gzis.read()) >= 0) {
    dbaos.write(b);
}

>>Sample String here<<
Size of bytes before: 18
Size of bytes after: 18