import java.lang.reflect.Constructor;
import com.loaderman.bean.Person;

public class Demo_Constructor {

  /**
   Class类的newInstance()方法是使用该类无参的构造函数创建对象, 如果一个类没有无参的构造函数,
   就不能这样创建了,可以调用Class类的getConstructor
   (String.class,int.class)方法获取一个指定的构造函数然后再调用Constructor类的newInstance
   ("张三",20)方法创建对象
    @throws Exception
 */
    public static void main(String[] args) throws Exception {
       Class clazz = Class.forName("com.heima.bean.Person");
        //Person p = (Person) clazz.newInstance();          通过无参构造创建对象
        //System.out.println(p);
        Constructor c = clazz.getConstructor(String.class,int.class);//获取有参构造
        Person p = (Person) c.newInstance("张三",23);         //通过有参构造创建对象
        System.out.println(p);
    }

}

package com.loaderman.bean;

public class Person {
    private String name;
    private int age;
    public Person() {
        super();

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