findPerimeterIsoscelesTriangle()

Step 1: Understand the problem and define the function

To find the perimeter of an isosceles triangle, we need to sum the lengths of all sides. An isosceles triangle has two equal sides and one different side. Let's call the length of the equal sides 'a' and the length of the different side 'b'. Thus, the formula to calculate the perimeter is: 2a + b. So, we shall define a function in Java that takes two parameters: 'a' and 'b'.

public double calculatePerimeter(double a, double b) {
    // To be implemented
    return 0.0;
}

Step 2: Implement the logic to calculate perimeter

As mentioned, the method to calculate the perimeter of an isosceles triangle is simply 2a + b. Thus, inside our function, we simply return this result.

public double calculatePerimeter(double a, double b) {
    return 2*a + b;
}

Step 3: Validate the inputs

Before performing the calculation, it is good practice to ensure the supplied lengths are valid, i.e., they should be non-negative. Let's add this validation to our function.

public double calculatePerimeter(double a, double b) {
    if(a < 0 || b < 0) {
        throw new IllegalArgumentException("Lengths of sides must be non-negative");
    }
    return 2*a + b;
}

Step 4: Test the function

Now that our function is implemented, we should test it with some sample inputs to ensure it works as expected.

public static void main(String[] args) {
    System.out.println(calculatePerimeter(3, 4));  // Should print: 10.0
    System.out.println(calculatePerimeter(5, 5));  // Should print: 15.0
}

Conclusion

In this post, we have implemented a function in Java to calculate the perimeter of an isosceles triangle. Always remember to validate your inputs and test your function with various inputs to ensure it works in all scenarios.

Here is the full code:

public class Main {
    public static double calculatePerimeter(double a, double b) {
        if(a < 0 || b < 0) {
            throw new IllegalArgumentException("Lengths of sides must be non-negative");
        }
        return 2*a + b;
    }

    public static void main(String[] args) {
        System.out.println(calculatePerimeter(3, 4));
        System.out.println(calculatePerimeter(5, 5));
    }
}