java: save string as gzip file

Have a look at GZIPOutputStream - you should be able to use this in exactly the same way as any other outputstream to write to a file - it'll just automatically write it in the gzip compressed format.

There are two orthogonal concepts here:

• Converting text to binary, typically through an OutputStreamWriter
• Compressing the binary data, e.g. using GZIPOutputStream

So in the end you'll want to:

• Create an OutputStream which writes to wherever you want the result (e.g. a file or in memory via a ByteArrayOutputStream
• Wrap that OutputStream in a GZIPOutputStream
• Wrap the GZIPOutputStream in an OutputStreamWriter using an appropriate charset (e.g. UTF-8)
• Write the text to the OutputStreamWriter
• Close the writer, which will flush and close everything else.

For example:

FileOutputStream output = new FileOutputStream(fileName);
try {
  Writer writer = new OutputStreamWriter(new GZIPOutputStream(output), "UTF-8");
  try {
    writer.write(text);
  } finally {
    writer.close();
  }
 } finally {
   output.close();
 }

Note that I'm closing output even if we fail to create the writer, but we still need to close writer if everything is successful, in order to flush everything and finish writing the data.

Same solution as Jon, just used try with resources

try (FileOutputStream output = new FileOutputStream("filename.gz");
     Writer writer = new OutputStreamWriter(new GZIPOutputStream(output), "UTF-8")) {
    
    writer.write("someText");
}