Understanding of class

package JavaReflcet;

import org.junit.Test;


public class ClassTest {
    /*
     obtain Class The way of example 
     */
    @Test
    public void test1() throws ClassNotFoundException {
//         Mode one ： Call the properties of the runtime class : .class
        Class clazz = person.class;
        System.out.println(clazz);

//         The way 2： Through the object of the runtime class 
        person p1 = new person();
        Class<? extends person> clazz2 = p1.getClass();
        System.out.println(clazz2);

//         The way 3： call Class Static method of ：forName(String classPath)
        Class clazz3 =Class.forName("JavaReflcet.person");
        System.out.println(clazz3);

//         The way 4： Using loaders for classes ：ClassLoader
        ClassLoader classLoader = ReflactionTest.class.getClassLoader();
        Class<?> clazz4 = classLoader.loadClass("JavaReflcet.person");
        System.out.println(clazz4);
    }
}

person The runtime class of can be regarded as a singleton :

clazz == clazz2        //true

clazz2== clazz3          //true