How do I programatically extract a certificate from a site and add it to my keystore?

Question

I'm trying fix--

javax.net.ssl.SSLHandshakeException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.

Found solution-- Does Android Volley support SSL?

But in this I have to integrate My_cert.crt file in APK which may change or expire in future.

I tried this link. But getting no certificates chain empty.

Is there another way of doing it. Please share. Thanks in advance.