## Thursday, 24 November 2016

### Chapter 12 Exercise 5, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

12.5 (IllegalTriangleException)
Programming Exercise 11.1 defined the Triangle class with three sides.
In a triangle, the sum of any two sides is greater than the other side.
The Triangle class must adhere to this rule. Create the IllegalTriangleException class,
and modify the constructor of the Triangle class to throw an IllegalTriangleException
object if a triangle is created with sides that violate the rule

public class Triangle extends GeometricObject {

private double side1;
private double side2;
private double side3;

public Triangle(double side1, double side2, double side3) throws IllegalTriangleException {
this.side1 = side1;
this.side2 = side2;
this.side3 = side3;
isValidTriangle();
}

public Triangle() {
this.side1 = 1;
this.side2 = 1;
this.side3 = 1;
}

@Override
public double getArea() {

double s = (side1 + side2 + side3) / 2.0;
return Math.pow(s * (s - side1) * (s - side2) * (s - side3), 0.5);
}

@Override
public double getPerimeter() {
return side1 + side2 + side3;
}

@Override
public String toString() {
return "Triangle{" +
"side1=" + side1 +
", side2=" + side2 +
", side3=" + side3 +
'}';
}

public static boolean isTriangle(double side1, double side2, double side3) {

return  ((side1 + side2 > side3) &&
(side1 + side3 > side2) &&
(side3 + side2 > side1));

}

public double getSide1() {
return side1;
}

public void setSide1(double side1) throws IllegalTriangleException {
this.side1 = side1;
isValidTriangle();
}

public double getSide2() {
return side2;
}

public void setSide2(double side2) throws IllegalTriangleException{
this.side2 = side2;
isValidTriangle();
}

public double getSide3() {
return side3;
}

public void setSide3(double side3) throws IllegalTriangleException {
this.side3 = side3;
isValidTriangle();
}

private void isValidTriangle() throws IllegalTriangleException{
if (!isTriangle(side1, side2, side3)) {
throw new IllegalTriangleException(side1, side2, side3);
}
}

public class IllegalTriangleException extends IllegalArgumentException {

private double s1;
private double s2;
private double s3;

public IllegalTriangleException(double s1, double s2, double s3) {
super("Not a real triangle:" + " side1 = " + s1 + " side2 = " + s2 + " side3 = " + s3);
this.s1 = s1;
this.s2 = s2;
this.s3 = s3;
}

public double getS1() {
return s1;
}

public double getS2() {
return s2;
}

public double getS3() {
return s3;
}

}
}


public class Exercise_05 {

public static void main(String[] args) {

Triangle t1;
try {
t1 = new Triangle(1, 1, 2000);
} catch (IllegalTriangleException e) {
e.printStackTrace();
}

}

}