Oop

[Wizard1988]

I have started learing OOP, and for homework my teacher assigned a program what calculates the area of a triangle. I wrote the program using some examples that I was given, and I understand the concept, but my program does not work correctly. Can someone tell me what is wrong


import java.io.*;
class Triangle{
private double a;
private double b;
private double c;
private double s =((a+b+c)/2);
void setSides (double aSide, double bSide, double cSide){
a = aSide;
b = bSide;
c = cSide;
}
double area(){
return Math.sqrt(s*((s-a)*(s-b)*(s-c)));
}
}


========================================
========================================

class TriangleArea {
/**
* @param args the command line arguments
*/
public static void main(String[] args)throws IOException{
BufferedReader console = new BufferedReader (new InputStreamReader (System.in));
System.out.println("Enter sides of the triangle\n");
System.out.print("Side a: ");
double a = Double.parseDouble(console.readLine());
System.out.print("Side b: ");
double b = Double.parseDouble(console.readLine());
System.out.print("Side c: ");
double c = Double.parseDouble(console.readLine());
if(a<=0|b<=0|c<=0){
System.out.println("Invalid Triangle");
}
else{
Triangle sometriangle = new Triangle();
sometriangle.setSides(a,b,c);
System.out.println("Area of this triangle is "+sometriangle.area());
}
}
}


The program compiles and executes, but when I enter the lengths of the sides I always get -0.0 as the area. Does anyboy know what I am doing wrong?

[NarayanaBuddepu]

Hey Buddy,

Everything is fine with your code. The only change you have to do is at the calculation of "s".

It must be calculated w r t the values of the sides but irrespective of that u r calculating it with the initial values and it results to 0.0

and hence your area will be 0.0

Try placing s= (a+b+c)/2 statement in the function either in setSides after the assignment statements or in the area() function before calculating the area.

Good Luck,
Narayana :-)

[doredson]

I agree. s should probably not be stored at all, since it can be derived purely from the lengths of the sides anyway.