FULL PRODUCT VERSION :
java version  " 1.7.0_25 " 
Java(TM) SE Runtime Environment (build 1.7.0_25-b17)
Java HotSpot(TM) Client VM (build 23.25-b01, mixed mode, sharing)

ADDITIONAL OS VERSION INFORMATION :
Windows Version 6.1.7601


A DESCRIPTION OF THE PROBLEM :
Deflater.setLevel() does not seem to set the compression level. Worse than a mere NOOP, if one calls deflater.setLevel() with an argument different that the already set by the constructor (explicitly or implicitly), the deflate stops working as expected.

Tested also with 1.6.0_07-b06 in Linux.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Run the program below

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
level in constructor: len=8 [120, -38, 3, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0]
level via setLevel(): len=8 [120, -38, 3, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0]

ACTUAL -
level in constructor: len=8 [120, -38, 3, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0]
level via setLevel(): len=0 [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]


REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.util.Arrays;
import java.util.zip.Deflater;

public class TestDeflater {

public static void test1 () throws Exception {
         byte[] output = new byte[16];
         Deflater compresser = new Deflater(Deflater.BEST_COMPRESSION);
         compresser.finish();
         int len = compresser.deflate(output);
         System.out.println( " level in constructor: len= " + len+  "   "  +Arrays.toString(output));
    }
    public static void test2 () throws Exception {
         byte[] output = new byte[16];
         Deflater compresser = new Deflater();
         compresser.setLevel(Deflater.BEST_COMPRESSION);
         compresser.setInput( " blah " .getBytes( " UTF-8 " ));
         compresser.finish();
         int len = compresser.deflate(output);
         System.out.println( " level via setLevel(): len= " + len+  "   "  +Arrays.toString(output));
    }
    public static void main (String[] args) throws java.lang.Exception
    {
            test1();
            test2();
    }
}
---------- END SOURCE ----------