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First use of variables and conditionals
this example from a Well House Consultants training course
Source code: Chloe.java Module: J050
/*
This is a first Java program that takes a parameter from the command line and depending on the value given produces varying results. It's designed to show the flow and structure of a very easy first Java program - but in the spirit of Java with heavy use of named pieces of code (functions) all included within a class. Note - this program does not include data validation so if the user fails to run it with an integer parameter, and untrapped exception will be thrown (i.e. you'll get a messy Java error message and the program will stop at that point!) */ public class Chloe { public static void main(String [] args) { System.out.println("Welcome to the world of Java"); System.out.println("What would you like to drink?"); // First use of a variable // Collect a whole number from the command line's // first String // age will be an "integer" a.k.a. int int age = Integer.parseInt(args[0]); System.out.print("We are working for age "); System.out.print(age); System.out.println(" years"); softdrink(); // Pass the age into harddrink so that we don't // offer the strong stuff to the young. We need // to pass it in so that it's available within // harddrink harddrink(age); } public static void softdrink() { System.out.println("\nFor the whole family"); System.out.println("Coca Cola"); System.out.println("Coffee"); System.out.println("Milk"); System.out.println("Water"); } public static void harddrink(int personsAge) { // Incoming parameter will be called personsAge // Could be the same name as the name in the calling // code or a different one. if (personsAge >= 18) { System.out.println("\nMummsies and Daddsies only"); System.out.println("Beer"); System.out.println("Wine"); System.out.println("Vodka"); System.out.println("Meths"); } } } /* ----------------------------- Sample outputs Dorothy-2:java grahamellis$ java Chloe Welcome to the world of Java What would you like to drink? Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0 at Chloe.main(Chloe.java:19) Dorothy-2:java grahamellis$ java Chloe 10 Welcome to the world of Java What would you like to drink? We are working for age 10 years For the whole family Coca Cola Coffee Milk Water Dorothy-2:java grahamellis$ java Chloe 18 Welcome to the world of Java What would you like to drink? We are working for age 18 years For the whole family Coca Cola Coffee Milk Water Mummsies and Daddsies only Beer Wine Vodka Meths Dorothy-2:java grahamellis$ */ Learn about this subject
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