how to check if a string is a plaintext or base64 format in android

Question

I want to check if a string is in Base64 encoded format or not in an android app. If it is in Base64 then i need to decode it and display the content after decoding. I have used the answer of Base 64 encode and decode example code and How to check whether the string is base64 encoded or not but the problem is how to compare/validate a Base64-regex with the string i got after reading a nfc tag. Thanks!

Answer 1

It might be late to answer this question but if you are till looking for this, then this might be helpfull.

if (org.apache.commons.codec.binary.Base64.isArrayByteBase64(base64String.getBytes())) {
                try{
                    chatTitle = new String(Base64.decode(base64String, Base64.DEFAULT), "UTF-8");
                } catch (Exception e) {}catch (UnsupportedEncodingException e) {
                    e.printStackTrace();
                }
            }

The org.apache.commons.codec.binary.Base64 comes default with Android

Answer 2

try

private boolean IsBase64Encoded(String value)
    {
        try {
            byte[] decodedString = Base64.decode(value, Base64.DEFAULT);
            BitmapFactory.decodeByteArray(decodedString, 0, decodedString.length);
            return true;
        } catch (Exception e) {
            return false;
        }
    }