toByteArray() won't be resolved for facebook login

Question

I am building an app which requires facebook login and authentication.

I am following

https://developers.facebook.com/docs/android/getting-started#create-app

I got this error: when I hit the facebook login button:

Multiple posts say that this code should resolve the error

Key hash doesn't match while facebook login in android

:

  try {
            PackageInfo info = getPackageManager().getPackageInfo(
                    "com.hitup.hitup",
                    PackageManager.GET_SIGNATURES);
            for (Signature signature : info.signatures) {
                MessageDigest md = MessageDigest.getInstance("SHA");
                md.update(signature.toByteArray());
                Log.d("KeyHash:", Base64.encodeToString(md.digest(), Base64.DEFAULT));
            }
        }
        catch (NameNotFoundException e) {

        }

        catch (NoSuchAlgorithmException e)
        {

        }

however the toByteArray() method cannot be resolved!

How can I resolve this error and achieve the simple facebook login for my app?

Answer 1

You must import a android.content.pm.Signature and not a java.security.Signature.

Answer 2

from Logcat you can get hash key of facebook please do copy from logcat which having Logcat tag "KeyHash" and put it in your project on developer.facebook site 

import android.content.pm.Signature;

      try {
        PackageInfo info = getPackageManager().getPackageInfo(
                **"do not forgot to your package name"**, PackageManager.GET_SIGNATURES);
        for (Signature signature : info.signatures) {
            MessageDigest md = MessageDigest.getInstance("SHA");
            md.update(signature.toByteArray());
            Log.d("KeyHash:",
                    Base64.encodeToString(md.digest(), Base64.DEFAULT));
        }
    } catch (NameNotFoundException e) {

    } catch (NoSuchAlgorithmException e) {

    }



OR 

1. for Android default keystore  : add this to in your terminal 
 
keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore | openssl sha1 -binary | openssl base64

2. for signed keystore 

keytool -exportcert -alias aliasname -keystore keystorename | openssl sha1 -binary | openssl base64