Each new call creates another object. Changing the name on one student does not change the other. The variable holds a reference. Copying the variable copies the reference, not a second student.
Passing an object to a method passes the reference. The method can change the object's fields. Reassigning the parameter to a new object does not change the caller's variable.
Example
b is not a second copy of the text. It is a second name for the same builder.
public class Pair {
public static void main(String[] args) {
StringBuilder a = new StringBuilder("Java");
StringBuilder b = a;
b.append(" 17");
System.out.println(a);
}
}String cannot be appended in place. StringBuilder can. a and b point at one builder, so append shows up through both names.
