Java Pass Parameters by value

Java Pass Parameters by value
This is well understood for an ordinary type of variable, for example, a variable of type int,string, but what if the variable is a class type? What is its value? Its value is its reference,
We can't change the value of the incoming parameter, what does this mean? It's just that we can't change the parameters we're passing in. Or for ordinary variables that's good to understand.
As an example:
int i=0;
public void Changeparam (int i)
{
i=9;
}
System.out.print (i);
What will the output be? It must be 0. Why? This is the characteristic of Java passing parameters by value, and we are passing in 0 instead of a variable that can be changed
So what about a class as a variable? We can't change it, it says it's a reference, which means we can't change the reference, but we can change the value of the referenced object.
It seems a little awkward, which means that the variable references an instance of the Class A We can't change it in the method body to refer to instance B of the class, but we can change the contents of instance a.
That's the way it is!