Can anyone see the problem in this code??

Can anyone see this problem?
The program takes in two numbers, gives a menu, the user selects an option, then the program calls the function, does the calculation and prints it on screen.
Problem is, it keeps displaying the calculation over and over in a loop for some reason, I cant see the problem?!
Any help greatly appriciated!!

---

//Project Program
class num{

//Declaring variables
static final double pi = 3.1416;
private int num1;
private int num2;

//Constructor
public num(int a, int b)
{
num1 = a;
num2 = b;
}


//Add Function
public void add()
{
Screen.newline();
Screen.cursorpos(35);
Screen.writeInt(num1);
Screen.message(" + ");
Screen.writeInt(num2);
Screen.message(" = ");
Screen.writeInt(num1+num2);
}

//Subtract Function
public void subtract()
{
Screen.newline();
Screen.cursorpos(35);
Screen.writeInt(num1);
Screen.message(" - ");
Screen.writeInt(num2);
Screen.message(" = ");
Screen.writeInt(num1-num2);
}
//Divion Function
public void divide()
{
Screen.newline();
Screen.cursorpos(35);
Screen.writeInt(num1);
Screen.message(" / ");
Screen.writeInt(num2);
Screen.message(" = ");
Screen.writeInt(num1/num2);
Screen.message(" . ");
Screen.writeInt(num1%num2);
}
//multiplication Function
public void multiply()
{
Screen.newline();
Screen.cursorpos(35);
Screen.writeInt(num1);
Screen.message(" * ");
Screen.writeInt(num2);
Screen.message(" = ");
Screen.writeInt(num1*num2);
}

//area Function
public void area()
{
Screen.newline();
Screen.cursorpos(35);
Screen.message(" Area = ");
Screen.writeDouble(pi*num1*num1);
}

//volume Function
public void volume()
{
Screen.newline();
Screen.cursorpos(35);
Screen.message(" Volume = ");
Screen.writeDouble(4*pi*(num1*num1*num1)/3);
}

//Circumference Function
public void Circumference()
{
Screen.newline();
Screen.cursorpos(35);
Screen.message(" Circumference = ");
Screen.writeDouble(pi*num1);
}


//Menu Options
public int call()
{
int opt1;

//Telling user the options
Screen.newline(2);
Screen.message("********************************************************************************");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 1: Add Variables -> Press 1 for Addition");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 2: Subtract Variables -> Press 2 for Subtraction");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 3: Divide Variables -> Press 3 for Division");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 4: Multiply Variables -> Press 4 for mulitiplication");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 5: Area of circle -> Press 5 to find area of a circle");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 6: Volume of circle -> Press 6 to find volume of a circle");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 7: Circumference of circle -> Press 7 to find Circumference of a circle");

Screen.newline(2);
Screen.cursorpos(2);
Screen.message("Option 9:Exit program -> Press 9 to exit");

Screen.newline(2);
Screen.message("********************************************************************************");

//statement to acknowlage user selection
Screen.cursorpos(30);
Screen.message("Option selected = ");
opt1 = Keyboard.readInt();
return opt1;

}

}

---

//Test Program
class numTest
{
public static void main(String[] args)
{

//Declaring Variables
int a;
int b;
int opt1;

//asking user to enter values into variables
Screen.cursorpos(30);
Screen.message("Enter two numbers");
Screen.newline(2);
Screen.message(" Number 1 will count as radius and diameter in option 5, 6 and 7 respectively");

//reading in numbers to variable
Screen.newline(2);
Screen.cursorpos(35);
a = Keyboard.readInt();
Screen.cursorpos(35);
b = Keyboard.readInt();


//creating instance
num result1 = new num(a,b);

//value returned from the call function & stored in opt1
opt1 = result1.call();

//Exit Function
while(opt1 !=9)
{
//IF function for menu
if (opt1== 1)
{
result1.add();
}
else if (opt1== 2)
{
result1.subtract();
}
else if (opt1== 3)
{
result1.divide();
}
else if (opt1== 4)
{
result1.multiply();
}
else if (opt1== 5)
{
result1.area();
}
else if (opt1== 6)
{
result1.volume();
}
else if (opt1== 7)
{
result1.Circumference();
}

}
}
}