I don't want to dive into something I have no idea of doing yet.
But my homework for this question was this, along with the code that I wrote to solve it:

package edu.carrollcc.cis132;

import java.util.Scanner;

/**
* Question 2 [10 Points] Warp fiction.
*
* The year is 2414 and a cannon has been invented that can fire a package into
* space at speeds faster than light. The cannon is also a phase-shifter so the
* package is frictionless and experiences no drag. Only a special landing pad
* can stop the package once it is in flight.
*
* Amazoz plans to use this technology to deliver packages to the Human colonies
* and has promised Same-minute delivery(tm). Amazoz has commissioned you to
* calculate how fast (in light-years per hour) the cannon needs to shoot the
* package to reach the destination in 59 seconds.
*
* The program should input a named destination or a double number indicating a
* light-year distance. The three named destinations include
* "Mars"(0.00000076051 ly), "Tau Ceti e"(11.90 ly), "Gliese 581 d"(20 ly)
*
* The program then outputs the light-years per second (lyph) speed the cannon
* needs to fire. Round the number to 6 decimal places in the output (commas not
* needed).
*
* For example: *User specifies Tau Ceti e Output: 726.101695 lyph
*
* Comments and style are worth up to 2 points.
*
* @author Brad Green
*/
public class Question2 {

public static void main(String[] args) {

final double lightYearPerHour = 61.01694915966;
double distance;
double ly;
String planets;
String planet1 = "Tau Ceti e";
String planet2 = "Mars";
String planet3 = "Gliese";

Scanner keyboard = new Scanner(System.in);

System.out.print("What is the destination or the distance in"
+ " light years: ");

if (keyboard.hasNextDouble()) {
distance = keyboard.nextDouble();
ly = lightYearPerHour * distance;
System.out.print("Calculated speed is: ");
System.out.printf("%.6f", ly);
System.out.print(" lyph. \n");
}
if (keyboard.hasNextLine()) {
planets = keyboard.nextLine();
if (planets.compareToIgnoreCase(planet1) == 0) {
ly = lightYearPerHour * 11.9;
System.out.print("Calculated speed is: ");
System.out.printf("%.6f", ly);
System.out.print(" lyph. \n");
}
if (planets.compareToIgnoreCase(planet2) == 0) {
ly = lightYearPerHour * 0.00000076051;
System.out.print("Calculated speed is: ");
System.out.printf("%.6f", ly);
System.out.print(" lyph. \n");
}
if (planets.compareToIgnoreCase(planet3) == 0) {
ly = lightYearPerHour * 20;
System.out.print("Calculated speed is: ");
System.out.printf("%.6f", ly);
System.out.print(" lyph. \n");

}
else
System.out.println("That is not a valid format.");
}

}
}

Is there a simpler way to do this?
Also, how can I get the input from the JOptionPane method like I did from the scanner class. ex:

input = JOptionPane.showInputDialog("Enter a distance or a planet: ");

So to parse the variable of "input" from a string to an int or double or whatever, how would I do that?

Don't know java, but creating a array of structures would be better. Would just have to loop through the array of structures comparing input string to structure elements to find required distance.



Alternatively I would image java would have implemented tables/lists/hashes where you can create a list of string indexes with string/numeric values.



Just some examples in other languages that should be fairly straight forward which will allow for easier maintenance/upkeep for larger lists if java has suitable equivalents.

This post was edited by AbDuCt on Mar 2 2014 03:56pm

Thanks, I semi understand. I'm just starting on increments this week. I havn't touched arrays at all yet, but I have briefly seen them in the book.

Essentially you are just creating a lookup table where you can search for the name of the planet a user inputted to grab its value from the table. Unfortunately I don't know the name of these for java. After a quick google search looks like HashMap() is the function you are looking for if you want to implement something like this:



I'm sure someone else will come along and add more needed details or a better method for storing string, double indexes.

Using this method will eliminate allot of your if/elseif parsing you are doing.

More information about hashmaps can be found here:

http://docs.oracle.com/javase/7/docs/api/java/util/HashMap.html

This post was edited by AbDuCt on Mar 2 2014 04:03pm

Yea, I'm pretty sure the prof. wanted us to parse all the if/else if statements. I was just mainly curious because I enjoy programming.