How can I read the content of a .pfx file in Java?

I have file.pfx file and also have a private key. How can I read the certificate in file.pfx in Java?

I have used this code:

import java.security.*;
import java.security.cert.Certificate;
import java.security.cert.X509Certificate;
import java.security.cert.CertificateException;
import javax.crypto.SecretKey;
import javax.security.auth.callback.*;
//These packages I have used.

public String readFile(String fn) { 
  String thisLine, ret = ""; 
  KeyStore ks = KeyStore.getInstance("pkcs12", "SunJSSE"); 
  ks.load(new FileInputStream(fn),"password".toCharArray()); 
  try { 
    Key key = ks.getKey("1", "password".toCharArray());
    Certificate[] cc = ks.getCertificateChain("1");
    X509Certificate certificate1 = (X509Certificate) cc[0];//Here it throws  java.lang.NullPointerException 
    ret += certificate1.getNotAfter(); 
    ret += certificate1.getNotBefore(); 
  } catch(Exception e) { 
    ret = "Cannot load, exception!";
  } 
  return ret; 
}