对java中方法参数的学习

/**
 * @author zhangyongzhi E-mail:[e-mail]
 * @version 创建时间：Dec 15, 2008 7:55:31 AM 
 * 对java中方法参数的练习. 
 * java中的方法参数有这么几个特点:
 * 1.方法不能修改基本类型的参数
 * 2.方法可以修改对象参数的状态
 * 3.方法不能让对象参数指向新的对象.
 */
public class TestClass {

	public static void main(String args[]) {
		String str = new String("World");
		char ch[] = { 'H', 'e', 'l', 'l', 'o' };
		change(str, ch);

// System.out.println(str + " and " + ch);
                  System.out.print(str + " and ");
		System.out.println(ch);

		People a = new People("zhang", 25);
		People b = new People("lili", 24);
		change(a, b); 
//参数 a, b 只是对象a, b 引用的一份拷贝,指向原来对象.参数a只是存放了对象a的引用的值,它
//的物理地址跟b不一样.  就相当于: int a = 5; int b = a; 一样, b=5, b跟a完全是两个变量.
		System.out.println(a.name);
		change(a);
		System.out.println(a.name);
	}

	public static void change(String str, char ch[]) {
		str = "Changed";
		ch[0] = 'C';
	}

	public static void change(People x, People y) {
		People temp = x;
		x = y;
		y = temp;
	}

	public static void change(People x) {
		x.name = "zhyzh";
		x.age = 20;
	}
	
}


class People {
	public String name;

	public int age;

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

输出结果:

World and Cello
zhang
zhyzh