public class Person{
    private String name;
    private Integer age;

    public String getName(){
        return name;
    }

    public void setName(String name){
        this.name = name;
    }

    public Integer getAge(){
        return age;
    }

    public void setAge(Integer age){
        this.age = age;
    }

    public Person(){

    }

    public Person(String name, Integer age){
        this.name = name;
        this.age = age;
    }

    public Person(String name){
        this.name = name;
    }

    public Person(Integer age){
        this.age = age;
    }

}

Person p = new Person();
Person p2 = new Person();

Class c1 = p.getClass();
Class c2 = p2.getClass();
System.out.print(c1 == c2);  // 输出为true,说明创建的两个对象使用的是同一份字节码文件对象

import java.lang.reflect.Constructor;
Class c3 = Person.class;  //得到字节码文件对象

Constructor [] constructors = c3.getConstructors(); // 获得构造器对象

for(Constructor constructor:constructors){
    System.out.println(constructor);
}

Constructor constr = c3.getConstructor(String.class); // 得到指定的构造器对象
Object obj = constr.newInstance("tom"); // 用得到的构造器对象创建该类的实例
Person cp = (Person)obj;
System.out.println(cp.getName());  //输出为tom

public class Student{

    private Student(){

    }

    public String toString(){
        return "Student [getClass()=" + getClass() + ",hashCode()=" +hashCode()+ ",toString()=" + super.toString() +"]";
    }
}