FontysICT-sem1

#Training Traffic Light

We are going to program traffic lights (popularly known as stop lights). Now it’s a pretty straightforward variant, but after theory in later chapters it will be extended. So save the code you create!

Analysis

Before we start typing code we always think about what we want to achieve:

• The client requires the code to be in English.
• I want to have the ability to create multiple objects of type TrafficLight, but I only want to program it once.
• A TrafficLight can have the colors (states) green', orange’, `red’: use English names for these states.
• For safety, when creating a TrafficLight, the state is always set to red.
• From red, the state can only become green, then orange, then red again.

Design

• A Console project to named Traffic.
• A class TrafficLight.
• This class has a private Field color of type String.
• Initial value of color: Red
• The class gets a method NextState() that gives the TrafficLight the next value of color.
• We also want to be able to ask a TrafficLight what the current color is: public String GetCurrentColor()

Realization.

• Create the items listed in the design.
• The method NextState returns the color after changing the color: public String NextState() {...}

A Console app has a mainmethod (public static void Main(string [] args)) in which you can put code like:

TrafficLight trafficLight = new TrafficLight();
// color has to be "Red".
Console.WriteLine(trafficLight.GetCurrentcolor());
trafficLight.NextState();
// color has to be "green".
Console.WriteLine(trafficLight.GetCurrentColor());
trafficLight.NextState();
// color has to be "orange".
Console.WriteLine(trafficLight.GetCurentColor());
trafficLight.NextState();
// and 'red' again!
Console.WriteLine(trafficLight.GetCurentColor());

The above code is somewhat sloppily put together: check for errors! Correct them if necessary and test the program. Can you think of any improvements to the program?

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