Java Reference
In-Depth Information
Let's now write the definition of the method setData of the class DClass . Because
bCh is a protected instance variable of the class BClass , it can be directly accessed in
the definition of the method setData . However, because bX is a private instance
variable of the class BClass , the method setData of the class DClass cannot directly
access bX . Thus, the method setData of the class DClass must set bX by using the
method setData of the class BClass . The definition of the method setData of the
class DClass can be written as follows:
public void setData( char ch, double v, int a)
{
super .setData(v);
bCh = ch;
//initialize bCh using the assignment
//statement
dA = a;
}
Note that the definition of the method setData contains the statement:
super .setData(v);
to call the method setData with one parameter (of the superclass), to set the instance
variable bX , and then directly set the value of bCh .
Next, let's write the definition of the method toString (of the class DClass ):
public String toString()
{
return ( super .toString() + "Subclass dA = " + dA + '\n');
}
The constructors' definitions are:
1
0
public DClass()
{
super ();
dA = 0;
}
public DClass( char ch, double v, int a)
{
super (ch, v);
dA = a;
}
The following program shows how the objects of BClass and DClass work:
public class ProtectedMemberProg
{
public static void main(String[] args)
{
BClass bObject = new BClass();
//Line 1
DClass dObject = new DClass();
//Line 2
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