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Java, A Beginner’s Guide, 5th Edition by Herbert Schildt

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Try This 12-1 A Computer-Controlled Traffic Light

TrafficLightDemo.java

Enumerations are particularly useful when your program needs a set of constants, but the actual values of the constants are arbitrary, as long as all differ. This type of situation comes up quite often when programming. One common instance involves handling the states in which some device can exist. For example, imagine that you are writing a program that controls a traffic light. Your traffic light code must automatically cycle through the light’s three states: green, yellow, and red. It also must enable other code to know the current color of the light and let the color of the light be set to a known initial value. This means that the three states must be represented in ...

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