convertfrommetric.java

Java 入门书的源码

//Copyright (c) 1998, Arthur Gittleman
//This example is provided WITHOUT ANY WARRANTY either expressed or implied.

/*  Tests the structure of the program
 *  to convert length using a menu to
 *  get the user's choice.  Uses stubs
 *  for the actual conversion methods.
 */

import iopack.Io;
public class ConvertFromMetric {
  public static void MetricToEnglish() {
    double meters;                // number of meters to convert              
    double toYards;               //  meters converted to yards
    int yards;                    //  integer part of toYards
    double excessYards;           //  fractional part of toYards
    double toFeet;                //  excessYards converted to feet
    int feet;                     //  integer part of toFeet  
    double excessFeet;            //  fractional part of toFeet
    float toInches;              //  excessFeet converted to inches
  
    meters = Io.readDouble("Enter the number of meters to convert");
    toYards = meters / .9144;
    yards = (int)Math.floor(toYards);
    excessYards = toYards - yards;
    toFeet = 3 * excessYards;
    feet = (int)Math.floor(toFeet);
    excessFeet = toFeet - feet;
    toInches = (float)(12 * excessFeet);
    if (meters <= 1)
      System.out.println(meters+ " meter converts to");                            
    else
      System.out.println(meters+ " meters convert to");
    System.out.print('\t');
    if (yards > 0) 
      if (yards  <= 1)  System.out.print(yards + " yard  ");
      else System.out.print(yards + " yards  ");
    if (feet > 0)
      if (feet <= 1) System.out.print(feet + " foot  ");
      else System.out.print(feet + " feet  ");
    if (toInches > 0)
      if (toInches <= 1) System.out.println(toInches + " inch");
      else System.out.println(toInches + " inches");
    if (yards == 0 && feet == 0 && toInches == 0)
      System.out.println(0 + " yards");
  }
  public static void EnglishToMetric() {
    System.out.println("Converting from yds,ft,in to meters");
  }
  public static void main(String [] args) {
    int choice;  
    do {
      System.out.println();  
      System.out.println("Choose from the following list");
      System.out.println("1.  Convert from meters to yds,ft,in");
      System.out.println("2.  Convert from yds,ft,in to meters");
      System.out.println("3.  Quit");
      choice = Io.readInt("Enter your choice, 1, 2 or 3"); 
      switch (choice) {
        case 1:
          MetricToEnglish();
          break;
        case 2:
          EnglishToMetric();
          break;
        case 3:  System.out.println("Bye, Have a nice day"); 
      }
    } while (choice != 3);
    Io.readString("Press any key to exit");   // Added for IDE use
  }           
}