Object-Oriented Design - Java Software Solutions: Foundations of Program Design - page 341

LISTING 7.17
//********************************************************************
// Num.java Author: Lewis/Loftus
//
// Represents a single integer as an object.
//********************************************************************
public class Num
{
private int value;
//-----------------------------------------------------------------
// Sets up the new Num object, storing an initial value.
//-----------------------------------------------------------------
public Num ( int update)
{
value = update;
}
//-----------------------------------------------------------------
// Sets the stored value to the newly specified value.
//-----------------------------------------------------------------
public void setValue ( int update)
{
value = update;
}
//-----------------------------------------------------------------
// Returns the stored integer value as a string.
//-----------------------------------------------------------------
public String toString ()
{
return value + "";
}
}
Num object is created and assigned to the second Num parameter. These changes are
reflected in the output printed at the end of the changeValues method.
However, note the final values that are printed after returning from the
method. The primitive integer was not changed from its original value, because
the change was made to a copy inside the method. Likewise, the last parameter
still refers to its original object with its original value. This is because the new Num
object created in the method was referred to only by the formal parameter. When