DeflaterOutputStream not writing anything to text file after compression

[Anka Rao]

Please suggest where my code is wrong..

It is printing all the content of input file (is having around 100 lines) with System.out.print ((char)i); But destination file is having data as xœ after running code for compression. Surprisingly, eclipse compiler is not giving any errors..

 
      try {

     FileInputStream fiscom = new FileInputStream ("Chapter1.java");
     FileOutputStream foscom = new FileOutputStream ("FileAfterCompression.txt"); 
     DeflaterOutputStream dos = new DeflaterOutputStream (foscom); 
     int i=0;
     System.out.println ("Compression of following data has started.. ");

     while (( i=fiscom.read() )!=-1) {
         dos.write ((byte)i);
         //System.out.print ( (char)i) ; 
     }  

     System.out.println ("Compression is completed.. "); 
     fiscom.close ();
     foscom.close ();
     dos.close (); 

} catch (Exception exatCompressDecompress) {
     System.out.println ("Exception in Compress/Decompress program ");
}

Console output :

Compression of following data has started..
Compression is completed..

[Maxim Karvonen]

Hi, Anka

My suggestion is that your are closing file output stream before deflater output stream. Deflater have an internal buffer and process data in "batches" by compressing them. It ocasionally write data and also finishes compression and flushes the buffer when close() method is called. However, file stream is closed one line above so all the remaining data are lost and the resulting file is "truncated". Switching an order should help. Or even better, you do not have to close the file stream by hand. DeflaterOutputStream will close the underlying stream when dos.close() is called.

BTW, do you get any exceptions running your program? An exception should happen in line 17, where DeflaterOutputStream tries to write into the already-closed file stream. So the code should say "Exception in Compress/Decompress program".

[Anka Rao]

Thanks Maxim.. It worked .. just closed DeflaterOutputStream before FileOutputStream..

[Tony Docherty]

Or better still do as Maxim suggested and don't close the FileOutputStream at all as this is an unnecessary step and as you have found out a potential bug. When you chain streams you only need to close the outer most stream, this closes all the chained streams in the correct order.

[Campbell Ritchie]

…and welcome to the Ranch