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Lecter Java: Program design - Chapter 7: Programming withmethods and classes

This chapter explores Java mechanisms that support the manipulation and calculation of values through method invocations; the use of class and instance variables; and the implementation of constructors, accessors, mutators, and facilitators. The examination begins with the method invocation process. | Programming with methods and classes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Methods Instance method Operates on a object (i.e., and instance of the class) String s = new String("Help every cow reach its " + "potential!"); int n = s.length(); Class method Service provided by a class and it is not associated with a particular object String t = String.valueOf(n); Instance method Class method Data fields Instance variable and instance constants Attribute of a particular object Usually a variable Point p = new Point(5, 5); int px = p.x; Class variable and constants Collective information that is not specific to individual objects of the class Usually a constant Color favoriteColor = Color.MAGENTA; double favoriteNumber = MATH.PI - MATH.E; Instance variable Class constants Task – Conversion.java Support conversion between English and metric values 1 gallon = 3.785411784 liters 1 mile = 1.609344 kilometers d degrees Fahrenheit = (d – . | Programming with methods and classes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Methods Instance method Operates on a object (i.e., and instance of the class) String s = new String("Help every cow reach its " + "potential!"); int n = s.length(); Class method Service provided by a class and it is not associated with a particular object String t = String.valueOf(n); Instance method Class method Data fields Instance variable and instance constants Attribute of a particular object Usually a variable Point p = new Point(5, 5); int px = p.x; Class variable and constants Collective information that is not specific to individual objects of the class Usually a constant Color favoriteColor = Color.MAGENTA; double favoriteNumber = MATH.PI - MATH.E; Instance variable Class constants Task – Conversion.java Support conversion between English and metric values 1 gallon = 3.785411784 liters 1 mile = 1.609344 kilometers d degrees Fahrenheit = (d – 32)/1.8 degrees Celsius 1 ounce (avdp) = 28.349523125 grams 1 acre = 0.0015625 square miles = 0.40468564 hectares Conversion Implementation public class Conversion { // conversion equivalencies private static final double LITERS_PER_GALLON = 3.785411784; private static final double KILOMETERS_PER_MILE = 1.609344; private static final double GRAMS_PER_OUNCE = 28.349523125; private static final double HECTARES_PER_ACRE = 0.40468564; Conversion implementation Conversion Implementation // temperature conversions methods public static double fahrenheitToCelsius(double f) { return (f - 32) / 1.8; } public static double celsiusToFahrenheit(double c) { return 1.8 * c + 32; } // length conversions methods public static double kilometersToMiles(double km) { return km / KILOMETERS_PER_MILE; } Conversion Implementation // mass conversions methods public static double litersToGallons(double liters) { return liters / LITERS_PER_GALLON; } public static double gallonsToLiters(double gallons) { return .