How to save a Pair of Keys from Strings in the KeyStore? (Java)

Question

Hello I generated a pair of keys with the following code

KeyPairGenerator generator = KeyPairGenerator.getInstance(RSA);
        generator.initialize(1024);
        KeyPair pair = generator.generateKeyPair();
        privateKey= pair.getPrivate();
        publicKey= pair.getPublic();

I wanted to save this keys in the cloud for later using them in an android App. So I use this code to save them as an String

 String privateKey = Base64.getEncoder().encodeToString(this.privateKey.getEncoded());

The problem is that I need to generate this keys again in the android app (not use them as an string) and save them into the KeyStore from android for saving them in the app secure.

Here is the documentation of the KeyStore and Keygenerator: https://developer.android.com/training/articles/keystore