Question

consider the following program and accompanying class

in program:

public static void main(string args)
{
point n = new point(1, 2);
point temp = new point(5, 1);
n.functionb(temp);
system.out.println(
.myx = \ + n.getmyx());
}

point class:

public class point
{
private int myx;
private int myy;

public point(int x, int y)
{
myx = x;
myy = y;
}

public int functiona(int y)
{
return y - 1;
}

public void functionb(point a)
{
myx = myx + a.myx;
myy = myy + a.myy;
}

public int getmyx()
{
return myx;
}
}

what output is generated when the program is executed?

• n.myx = 5
• n.myx = 1
• n.myx = 6

Explanation:

🆕 New Concept Discovered: Object-Oriented Parameter Passing
How objects and references behave when passed to methods.

Step 1: Analyze the initial state of the objects

In the main method, two Point objects are instantiated:

1. Point n = new Point(1, 2);

• This creates an object n where n.myX = 1 and n.myY = 2.

1. Point temp = new Point(5, 1);

• This creates an object temp where temp.myX = 5 and temp.myY = 1.

Step 2: Trace the method call n.functionB(temp)

The method functionB is called on the object n with temp passed as the argument a:

public void functionB(Point a)
{
    myX = myX + a.myX;
    myY = myY + a.myY;
}

Inside this method:

• myX and myY refer to the instance variables of the calling object, which is n.
• a.myX and a.myY refer to the instance variables of the passed object a (which is temp).

Let's calculate the new value for n.myX:

$$ \text{new } myX = \text{current } myX + a.myX $$

$$ \text{new } myX = 1 + 5 = 6 $$

Step 3: Determine the output

After n.functionB(temp) finishes executing, the program prints the value of n.getMyX():

System.out.println("n.myX = " + n.getMyX());

Since n.myX was updated to 6, the printed output is:
n.myX = 6

Answer:

n.myX = 6