Other information about methods

A method can not alter the values of any of its arguments. Thus the following is not valid code and will not compile.

public static int increment(int i)
{
    i += 3;           // this is not allowed, code will not compile
    return i;
}

You do not have to restrict yourself to calling additional methods just from the main method. If you have two or more additional methods one may call another.

Exercise 6.2

(9 marks)

Starting with the class MultMethEx1 you wrote for the previous exercise, make a new version of the class called MultMethEx2.

(i)

Add a new method called calcTriangleArea that performs the same calculation as printTriangleArea did, but instead of printing the area to the screen, it returns the area as a double. Modify main to use both methods and show that they produce the same result.

(ii)

Change the code in the method printTriangleArea so that it uses the new method calcTriangleArea instead of calculating the area itself. No changes to main should be necessary. Demonstrate that your program produces the same result.

(iii)

Add a method testIfValidTriangle which takes the three sides as arguments and checks that they form a valid triangle, according to the criteria given in the previous exercise. This method should return a boolean value: true if the sides do make a valid triangle, or false if not. Use the testIfValidTriangle method in the main method to validate the input before trying to calculate the area.

Note that in answering question (ii) you have benefited from having encapsulated a well-defined part of your program inside a separate method (printTriangleArea). This allows you to modify the internal workings of this method without requiring any changes elsewhere in the program where the method is used.

Include the program listings and sample outputs from all the questions above in your lab book.