This code is used to generate the key fragments in android using facebook.

getKeyHash.java

try {
    PackageInfo info = getActivity().getPackageManager().getPackageInfo(getActivity().getPackageName(), PackageManager.GET_SIGNATURES);
    for (android.content.pm.Signature signature : info.signatures) {
        MessageDigest md;
        md = MessageDigest.getInstance("SHA");
        md.update(signature.toByteArray());
        String something = new String(Base64.encode(md.digest(), 0));
        //this is key has of facebook
        Log.e("fb_hash", something);
    }
}
catch (PackageManager.NameNotFoundException e1) {
    // TODO Auto-generated catch block
    Log.e("name not found", e1.toString());
}
catch (NoSuchAlgorithmException e) {
    // TODO Auto-generated catch block
    Log.e("no such an algorithm", e.toString());
}
catch (Exception e){
    Log.e("exception", e.toString());
}
Log.e("DATA", "ya viene fb");