Does every Android phone support SHA-256

According to the Android Documentations for MessageDigest, SHA-256 is supported since API 1.

All Android devices support SHA-256. The NoSuchAlgorithmException indicates that a requested algorithm could not be found and is necessary because the method takes a String argument for the algorithm name. If you passed in "foo-256", the method's only recourse is to throw a NoSuchAlgorithmException because, for reasons beyond my understanding, there's no algorithm called "foo-256". Assuming you're passing in a name you're sure is an algorithm that Android can use, you'll never see that exception.

Add NoSuchAlgorithmException as below:

public static String SHA256 (String text) throws NoSuchAlgorithmException {

    MessageDigest md = MessageDigest.getInstance("SHA-256");

    md.update(text.getBytes());
    byte[] digest = md.digest();

    return Base64.encodeToString(digest, Base64.DEFAULT);
}