Passing Parameters

Hi,
I am a newbie and would appreciate it if someone could help me with the following code that I found on an online tutorial.
Thanks in advance,
Gus


class PassObj
{
int n1;
int n2;
// constructor
PassObj()
{
n1 = 0;
n2 = 0;
}

PassObj(int p1, int p2)
{
n1 = p1;
n2 = p2;
}

void multiply(PassObj p1)
{
int temp;
temp = p1.n1 * p1.n2;
System.out.println("Multiplication is " + temp);
}
public static void main(String args[])
{
PassObj obj1 = new PassObj(5,6);
PassObj obj2 = new PassObj();
obj2.multiply(obj1);
}
}

This is a program I got from a Java tutorial online. If I give my understanding of it could someone please tell me if I am correct or tell me where I have gone wrong. I am a newbie so all help is greatly appreciated.

1. The class PassObj has two int variables n1 & n2.
2. These as initialised to zero.
3. In Main, there are 2 instances of the class PassObj created. These are obj1 & obj2.
4. The multiply method is called with parameters 5 & 6 passed to it. The multiplication is done and the result is shown in the console.
My main issues are what is the point of:

PassObj(int p1, int p2)
{
n1 = p1;
n2 = p2;
}
and does the instantiation PassObj obj1 = new PassObj(5,6); actually pass parameters to the above constructor.