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Having Methods Take Constant Parameters (Java)

Programmers, I have another question about an exercise in "The Java Programming Language, Fourth Edition" by Ken Arnold, James Gosling, and David Holmes. Exercise 2.17 reads as follows: "Add two turn methods to [class] Vehicle: one that takes a number of degrees to turn and one that takes either of the constants Vehicle.TURN_LEFT or Vehicle.TURN_RIGHT." Is there a way to force a method to only take particular constant parameters? Simply changing the relevant method signatures like so: public void turn(int degrees) public void turn(final int degrees) isn't enough to prevent compile-time errors. I'd appreciate anyone's input on this question. Thank you. Peter

16th Feb 2017, 7:08 PM
Peter Hubbard
Peter Hubbard - avatar
2 Respuestas
+ 4
If you want to accept only fixed values, then you should create an enum for that: enum TURN { LEFT(-30), RIGHT (30); private int degree; private TURN(int degree) { this.degree = degree; } public int getDegree() { return degree; } } public void turn(TURN t) { turn(t.getDegree()); }
16th Feb 2017, 7:48 PM
Tamás Barta
Tamás Barta - avatar
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This was helpful. Thank you!
16th Feb 2017, 10:01 PM
Peter Hubbard
Peter Hubbard - avatar