import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.KeyStore;
public class MainClass {
public static void main(String args[]) throws Exception {
char[] oldpass = args[0].toCharArray();
char[] newpass = args[1].toCharArray();
String name = "mykeystore";
FileInputStream in = new FileInputStream(name);
KeyStore ks = KeyStore.getInstance("JKS");
ks.load(in, oldpass);
in.close();
FileOutputStream output = new FileOutputStream(name);
ks.store(output, newpass);
output.close();
}
}