java 内存分析之堆栈空间

package Demo;

public class Demo {
    public static void main(String[] args) {
        Demo demo = new Demo();  
        int date = 9;
        BirthDate d1 = new BirthDate(7, 7, 1970);
        BirthDate d2 = new BirthDate(5, 8, 2000);
        demo.change1(date);
        demo.change2(d1);
        demo.change3(d2);

    }
    public void change1(int i) {
        i = 1234;
    }
    public void change2(BirthDate b) {
        b = new BirthDate(22, 2, 2004);
    }
    public void change3(BirthDate b) {
        b.setDay(22);
    }
}

测试类