java gzip convert string to gzip / gzip to string

GzipTest.java

package gzip;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStreamReader;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;

public class GzipTest {
	public static void main(String[] args) throws Exception {
		String string = "test gzip. this will compress and decompress this string";

		System.out.println("after compress:");
        byte[] compressed = compress(string);
        System.out.println(compressed);
        System.out.println("after decompress:");
        String decomp = decompress(compressed);
        System.out.println(decomp);
	}
	
	public static byte[] compress(String str) throws Exception {
	    if (str == null || str.length() == 0) {
	        return null;
	    }
	    System.out.println("String length : " + str.length());
	    ByteArrayOutputStream obj=new ByteArrayOutputStream();
	    GZIPOutputStream gzip = new GZIPOutputStream(obj);
	    gzip.write(str.getBytes("UTF-8"));
	    gzip.close();
	    
	    return obj.toByteArray();
	 }
	
	  public static String decompress(byte[] str) throws Exception {
	    if (str == null ) {
	        return null;
	    }
	    
	    GZIPInputStream gis = new GZIPInputStream(new ByteArrayInputStream(str));
	    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;
	 }
}