gzip - compression and decompression of string data in java -

i using following code compress , decompress string data, problem facing is, getting compressed without error, decompress method throws following error.

exception in thread "main" java.io.ioexception: not in gzip format

public static void main(string[] args) throws exception {         string string = "i hhhhhhhhhhhhhhhhhhhhhhhhhhhhh"                 + "bjggujhhhhhhhhh"                 + "rggggggggggggggggggggggggg"                 + "esfffffffffffffffffffffffffffffff"                 + "esffffffffffffffffffffffffffffffff"                 + "esfekfgy enter code here`etd`enter code here wdd"                 + "heljwidgutwdbwdq8d"                 + "skdfgysrdsdnjsvfyekbdsgcu"                 +"jbujsbjvugsduddbdj";         system.out.println("after compress:");         string compressed = compress(string);         system.out.println(compressed);         system.out.println("after decompress:");         string decomp = decompress(compressed);         system.out.println(decomp);     }        public static string compress(string str) throws exception {         if (str == null || str.length() == 0) {             return str;         }         system.out.println("string length : " + str.length());         bytearrayoutputstream obj=new bytearrayoutputstream();         gzipoutputstream gzip = new gzipoutputstream(obj);         gzip.write(str.getbytes("utf-8"));         gzip.close();         string outstr = obj.tostring("utf-8");         system.out.println("output string length : " + outstr.length());         return outstr;      }        public static string decompress(string str) throws exception {         if (str == null || str.length() == 0) {             return str;         }         system.out.println("input string length : " + str.length());         gzipinputstream gis = new gzipinputstream(new bytearrayinputstream(str.getbytes("utf-8")));         bufferedreader bf = new bufferedreader(new inputstreamreader(gis, "utf-8"));         string outstr = "";         string line;         while ((line=bf.readline())!=null) {           outstr += line;         }         system.out.println("output string lenght : " + outstr.length());         return outstr;      } 

still couldn't figure out how fix issue!!!

this because of

string outstr = obj.tostring("utf-8"); 

send byte[] can bytearrayoutputstream , use such in bytearrayinputstream construct gzipinputstream. following changes need done in code.

byte[] compressed = compress(string); //in main method  public static byte[] compress(string str) throws exception {     ...     ...     return obj.tobytearray(); }  public static string decompress(byte[] bytes) throws exception {     ...     gzipinputstream gis = new gzipinputstream(new bytearrayinputstream(bytes));     ... }