java反射 java.lang.IllegalArgumentException: wrong number of arguments

很多人学习反射的时候，回碰到的一个异常，

举个例子:这个类里面有四个构造函数

public class Person {

	public Person() {

	}

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

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

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

	public String getName() {
		return name;
	}

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

	public int getAge() {
		return age;
	}

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

	@Override
	public String toString() {
		return "[" + this.name + "  " + this.age + "]";
	}

	private String name;
	private int age;
}

调用的时候

	public static void test4(String className){
		Class<?> demo1 = null;
		try {
			demo1=Class.forName(className);
		} catch (ClassNotFoundException e) {
			e.printStackTrace();
		}
		
		Person person1 = null;
		Person person2 = null;
		Person person3 = null;
		Person person4 = null;
		
		Constructor<?> cons[] = demo1.getConstructors();
		try {
			person1 = (Person) cons[0].newInstance();
			person2 = (Person) cons[1].newInstance("xxx");
			person3 = (Person) cons[2].newInstance(22);
			person4 = (Person) cons[3].newInstance("xxx",22);
		} catch (Exception  e) {
			e.printStackTrace();
		}
		
		System.out.println(person1);
		System.out.println(person2);
		System.out.println(person3);
		System.out.println(person4);
	}

这样子就会报错，原因在于，赋值的时候和构造函数里面顺序是相反的，希望网上教程不要拿过来复制，粘贴，自己也动动手，免得对初学者造成误导，写下！