This app has no Android Key hashes configured. - Login with Facebook SDK

I have problem about login with facebook acount in my application. I read to Facebook Doc. And I did all step as Facebook Doc.

First in login with facebook acount in app - SUCCESSFUL ! and than logout in application. I want to login again with my facebook acount. But not working !! And I took this Excepiton ! Please help me !

Exception : This app has no Android Key hashes configured.Configure your app key hashes at http:developers.facebook.com/apps/"APP ID"

Finaly; I used to part of code for HashKey Genarate

 try {
        PackageInfo info =     getPackageManager().getPackageInfo("MY PACKAGE NAME",     PackageManager.GET_SIGNATURES);
        for (android.content.pm.Signature signature : info.signatures) {
            MessageDigest md = MessageDigest.getInstance("SHA");
            md.update(signature.toByteArray());
            String sign=Base64.encodeToString(md.digest(), Base64.DEFAULT);
            Log.e("MY KEY HASH:", sign);
          //  Toast.makeText(getApplicationContext(),sign,     Toast.LENGTH_LONG).show();
        }
} catch (NameNotFoundException e) {
} catch (NoSuchAlgorithmException e) {
}

I resolved my issue. I should have done setting on Facebook. Steps :

Go to facebook developer's page : https://developers.facebook.com/
Open the App tabs and than click the Setting
Paste the generate hashkey on HashKey's field = If you don't have it yet, get your key hash part of code
And than Single Sign On will be "Yes" : Single Sign On: Enable this setting.

I wanted to share my resolve. Maybe someone need this solution. Good Luck !

You need not generate your hash key. When you will try to access facebook from your app, you will get an error msg saying following "[Hash Key]" is not registered or configured. Just copy that key and go to developer.facebook.com where you have registered your app for facebook verification and include under key hashes.

Remember : For every device, the hash key may be different. You need to include it freshly.

By default this key should do : 2jmj7l5rSw0yVb/vlWAYkK/YBwk=

Also, before everything, you need to provide facebook with your App details, along with screenshots of where you are using facebook features and reasons for why you are using. They need to verify that.

To generate a hash of your release key, run the following command on Mac or Windows substituting your release key alias and the path to your keystore. On OS X, run:

keytool -exportcert -alias <RELEASE_KEY_ALIAS> -keystore <RELEASE_KEY_PATH> | openssl sha1 -binary | openssl base64

On Windows, use:

keytool -exportcert -alias <RELEASE_KEY_ALIAS> -keystore <RELEASE_KEY_PATH> | openssl sha1 -binary | openssl base64

Ref: https://developers.facebook.com/docs/android/getting-started/#create_hash

If you haven't published your app and just want to use the debug version hash, you can get it from your debug keystore with this command:

keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore | openssl sha1 -binary | openssl base64