The getClass().getInterfaces() method return an array of Class that represents the interfaces implemented by an object.

package org.kodejava.lang;

import java.util.Date;
import java.util.Calendar;

public class ClassInterfaces {
    public static void main(String[] args) {
        // Get an instance of Date class
        Date date = Calendar.getInstance().getTime();

        // Get all interfaces implemented by the java.util.Date class and
        // print their names.
        Class<?>[] interfaces = date.getClass().getInterfaces();
        for (Class<?> i : interfaces) {
            System.out.printf("Interface of %s = %s%n", date.getClass().getName(), i.getName());
        }

        // For the primitive type the interface will be an empty array.
        interfaces = char.class.getInterfaces();
        for (Class<?> i : interfaces) {
            System.out.printf("Interface of %s = %s%n", char.class.getName(), i.getName());
        }
    }
}

The java.util.Date class implements the following interfaces:

Interface of java.util.Date = java.io.Serializable
Interface of java.util.Date = java.lang.Cloneable
Interface of java.util.Date = java.lang.Comparable