<pre name="code" class="java">import java.lang.reflect.Constructor;

import java.lang.reflect.Field;

import java.lang.reflect.Method;

class Point{

	int x;

	private int y;

	public Point(){

		x = 1;

		y = 2;

	}	

	public void setX(int x) {

		this.x = x;

	}

	public void setY(int y) {

		this.y = y;

	}

	private Point(int x){

		this();

		this.x = x;

	}

	public Point(int x, int y) {

		super();

		this.x = x;

		this.y = y;

	}

	public void printPoint(){

		System.out.println("x = " + x + " , y = " + y);

	}

}

public class ReflectTest2 {

	public static void main(String[] args) throws Exception {

		//使用第一种方法创建对象

		Class cls1 = Class.forName("Point");

		Constructor con1 = cls1.getConstructor(int.class,int.class);

		Point p1 = (Point) con1.newInstance(5,6);

		p1.printPoint();

		//使用另外一种方法创建对象

		Class cls2 = Point.class;

		Point p2 = (Point) cls2.newInstance();//无參构造函数

		p2.printPoint();

		//使用第三种方法创建对象

		Class cls3 = p1.getClass();

		//使用p1对象的setX方法将x值改动为10

		Method m1 = cls3.getMethod("setX", int.class);

		m1.invoke(p1, 10);

		p1.printPoint();

		/*

		 * Note:

		 * getDeclaredConstructor能够返回指定參数的构造函数，

		 * 而getConstructor仅仅能放回指定參数的public的构造函数

		 * */

		Constructor con2 = cls3.getDeclaredConstructor(int.class);

		//訪问私有变量、函数须要设置accessible

		con2.setAccessible(true);

		Point p4 = (Point) con2.newInstance(3);

		p4.printPoint();

		//Field f1 = cls3.getField("y");//error

		Field f1 = cls3.getDeclaredField("y");

		f1.setAccessible(true);

		//获取p1的y值

		System.out.println(f1.get(p1));

	}

}