You can encrypt many more than 200 characters
But here is a quick (and dirty) example on how to do it:

Let’s assume that you have generated a public key (or somebody gave you one) as a file “public.cer”, then you can do this:

File keyFile = new File("public.cer");
byte[] encodedKey = new byte[(int)keyFile.length()];

new FileInputStream(keyFile).read(encodedKey);

X509EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(encodedKey);

KeyFactory kf = KeyFactory.getInstance("RSA");
PublicKey pk = kf.generatePublic(publicKeySpec);

Cipher rsa = Cipher.getInstance("RSA");

rsa.init(Cipher.ENCRYPT_MODE, pk);
OutputStream os = new CipherOutputStream(
        new FileOutputStream("encrypted.rsa"), rsa);

Writer out = new OutputStreamWriter(os);
out.write("Very Large '200 character'   message, that will be encrypted...");
out.close();
os.close();

Good luck!

Thanks.

Xandra