java - Extracting SFX 7-Zip -

i want extract 2 specific files .zip file. tried following library:

zipfile zipfile = new zipfile("myzip.zip"); 

result:

exception in thread "main" java.util.zip.zipexception: error in opening zip file 

i tried:

public void extract(string targetfilename) throws ioexception {     outputstream outputstream = new fileoutputstream("targetfile.foo");     fileinputstream fileinputstream = new fileinputstream("myzip.zip");     zipinputstream zipinputstream = new zipinputstream(new bufferedinputstream(fileinputstream));     zipentry zipentry;      while ((zipentry = zipinputstream.getnextentry()) != null)     {         if (zipentry.getname().equals("targetfile.foo"))         {             byte[] buffer = new byte[8192];             int length;             while ((length = zipinputstream.read(buffer)) != -1)             {                 outputstream.write(buffer, 0, length);             }             outputstream.close();             break;         }     } } 

result:
no exception, empty targetfile.foo file.

note .zip file of type sfx 7-zip , had .exe extensions may reason failure.