所以我是一个绝对的初学者并制作了这个Change-Making程序，它询问用户输入但它没有在输入对话框中输出，请帮助..我有以下这两个类文件。
Class＃1- ChangeMakerTester.java
package changemaker;
import javax.swing.JOptionPane; // for input
/**
* A test class for the ChangeMaker class
*/
class ChangeMakerTester {
public static void main(String[] args) {
double amountDue ; // total cost of purchases
double amountPaid ; // amount paid
String input ; // returned by input dialog box
// get amount due and amount paid from user
input = JOptionPane.showInputDialog( "What is the amount due?") ;
amountDue = Double.parseDouble(input) ;
input = JOptionPane.showInputDialog( "What is the amount paid?") ;
amountPaid = Double.parseDouble(input) ;
// create a ChangeMaker object (myChangeMaker) using these values
ChangeMaker myChangeMaker = new ChangeMaker(amountDue, amountPaid) ;
// call computeChange method for myChangeMaker object
myChangeMaker.computeChange() ;
}
} // end of ChangeMakerTester class declaration
第2课 - ChangeMaker.java
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package changemaker;
/**
*
* @author CarlosC
*/
/**
* Computes the change due - using the minimum coinage possible - when the
* user enters the cost of a purchase and the amount tendered
*/
public class ChangeMaker
{
// instance var's
private double amountDue; //total cost of purchases
private double amountTendered; //amound paid
private int dollarsDue; //number of dollar coins due in change
private int quartersDue; // number of quarters due
private int dimesDue; // number of dimes due
private int nickelsDue; // number of nickels due
private int penniesDue; // number of pennies due
/**
* Constructs a ChangeMaker object
* @param totalDue the amount of the purchase
* @param amountReceived the amount tendered (paid)
*/
public ChangeMaker (double totalDue, double amountReceived)
{
// initialize instance var's
amountDue = totalDue;
amountTendered = amountReceived;
// other instance var's automatically initialized to 0
System.out.printf("%nAmount Due: $%.2f", amountDue);
System.out.printf("%nAmount Received: $%.2f", amountTendered);
}
/**
* Computes the number of coins of each denomination to be given as change
*/
public void computeChange()
{
int changeDue; // total change due, in cents
if (amountDue == amountTendered)
{
System.out.println("\nExact change! Thanks and have a nice day!");
}
else if (amountDue > amountTendered) //owes more money!
{
System.out.printf("\nLo siento, you still owe me another %.2f",
amountDue - amountTendered);
}
else //change is due
{
//compute change due, in cents for easier calculations
changeDue = (int) Math.round((amountTendered - amountDue) * 100);
//compute number of dollars due, and reduce change due accordingly
dollarsDue = changeDue / 100; //note integer divide!
changeDue = changeDue % 100; //...and mod operation
// now do the same for all other coins
quartersDue = changeDue / 25;
changeDue = changeDue % 25;
dimesDue = changeDue / 10;
changeDue = changeDue % 10;
nickelsDue = changeDue /5;
changeDue = changeDue % 5;
penniesDue = changeDue; //change due is <= 4 cents
//activate change dispenser
this.giveChange();
}
}
// dispenses (i.e., prints) the coins comprising the change
private void giveChange()
{
System.out.println("\nYour change:");
if (dollarsDue !=0)
{
System.out.println("\t" + dollarsDue + " dollar(s)");
}
if (quartersDue != 0)
{
System.out.println("\t" + quartersDue + " quarter(s)");
}
if (dimesDue != 0)
{
System.out.println("\t" + dimesDue + " dime(s)");
}
if (nickelsDue != 0)
{
System.out.println("\t" + nickelsDue + " nickel(s)");
}
if (penniesDue != 0)
{
System.out.print("\t" + penniesDue);
if (penniesDue == 1)
{
System.out.println(" penny");
}
else
{
System.out.println(" pennies");
}
}
System.out.println("\nThanks and have a nice day!");
}
} //end of ChangeMaker class declaration ===================================