How to validate a public and private key pair in Java

Question

Is there a way to validate in java if the given private key, say certain *.key file matches with the certain public key, to a certain .pub file using RSA algorithm?

Answer 1

The answer that was marked as being correct wastes a lot of CPU cycles. This answer is waaaay more CPU efficient:

KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(2048);

KeyPair keyPair = keyGen.generateKeyPair();
RSAPrivateCrtKey privateKey = (RSAPrivateCrtKey) keyPair.getPrivate();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();

// comment this out to verify the behavior when the keys are different
//keyPair = keyGen.generateKeyPair();
//publicKey = (RSAPublicKey) keyPair.getPublic();

boolean keyPairMatches = privateKey.getModulus().equals(publicKey.getModulus()) &&
    privateKey.getPublicExponent().equals(publicKey.getPublicExponent());