ADDITIONAL JAVA TOPICS - Java Programming: From Problem Analysis to Program Design - page 974

//Method to return the value of x as a string
public String toString()
{

return (String.valueOf(x));

}

}

Consider the following statements:

IntClass firstNum = new IntClass(); //Line 1

IntClass secondNum = new IntClass(5); //Line 2

int num; //Line 3

The statement in Line 1 creates the object firstNum and initializes it to 0 . The statement
in Line 2 creates the object secondNum and initializes it to 5 . The statement in Line 3
declares num to be an int variable. Now consider the following statements:

firstNum.setNum(24); //Line 4
secondNum.addToNum(6); //Line 5
num = firstNum.getNum(); //Line 6
The statement in Line 4 sets the value of firstNum (in fact, the value of the data member
x of firstNum )to 24 . The statement in Line 5 updates the value of secondNum to 11
(the previous value 5 is updated by adding 6 to it.) The statement in Line 6 retrieves the
value of the object firstNum (the value of the data member x ) and assigns it to num .
After this statement executes, the value of num is 24 .
The following statements output the values of firstNum and secondNum (in fact, the
values of their data members):

System.out.println("firstNum = " + firstNum);
System.out.println("secondNum = " + secondNum);

Table D-4 shows how variables of int type and the corresponding reference variables of
IntClass type work.

TABLE D-4 Variables of int Type and the Corresponding Reference Variables of IntClass

int IntClass

Declaration
without or
with
initialization

IntClass x, y;
x = new IntClass();
y = new IntClass(5);

int x, y ¼ 5;

x ¼ 24; x.setNum(24);

Assignment

y ¼ x; y.setNum(x.getNum());

x ¼ x + 10; x.addToNum(10);

Addition

x ¼ x + y; x.addToNum(y.getNum());