Einfacher Währungsumrechner – Ich bin auf der Suche nach Feedback ⇐ Java

[Guest]

Dies ist mein grundlegender Währungsumrechner für meinen Einführungskurs in Java. Ich soll in der Lage sein, mit statischen Kursen zwischen Yen, Dollar, Pfund und Euro umzurechnen. Es funktioniert, aber ich war neugierig, ob ich es auf die effizienteste Art und Weise gemacht habe. Es scheint ziemlich lang zu sein und sieht aus wie ein riesiges Durcheinander. Ich möchte nur ein Feedback.

import java.util.Scanner;

public class currency
{

public currency()
{
char us_dollar_sym = 36;
char pound_sym = 163;
char yen_sym = 165;
char euro_sym = 8364;

String us_dollar = "Dollars";
String pound = "Pounds";
String yen = "Yen";
String euro = "Euros";
double rate = 0;

// Interface
System.out.println("Welcome to the Currency Converter Program \n");
System.out.println("Use the following codes to input your currency choices: \n 1 - US dollars \n 2 - Euros \n 3 - British Pounds \n 4 - Japanese Yen \n");

//
System.out.println("Please choose the input currency:");
Scanner in = new Scanner(System.in);
int choice = in.nextInt();

String inType = null;
switch(choice) {
case 1: inType = "US Dollars >> " + us_dollar_sym; break;
case 2: inType = "Euros >> " + euro_sym; break;
case 3: inType = "British Pounds >> " + pound_sym; break;
case 4: inType = "Japanese Yen >> " + yen_sym; break;
default:
System.out.println("Please restart the program & enter a number from the list.");
return;
}

System.out.println("Please choose the output currency");
int output = in.nextInt();

System.out.printf("Now enter the input in " + inType);
double input = in.nextDouble();

if (choice == output)
System.out.println("Same currency no need to convert");

if (choice == 1 && output == 2)
{
double dollar_euro_rate = 0.78391;
rate = input * dollar_euro_rate;
System.out.printf( "%s" + input + " at a conversion rate of " + dollar_euro_rate + " Dollars to %s = %.2f\n", (char)us_dollar_sym, euro, rate);
}
else if (choice == 1 && output == 3){
double dollar_pound_rate = 0.621484;
rate = input * dollar_pound_rate;
System.out.printf( "%s" + input + " at a conversion rate of " + dollar_pound_rate + " Dollars to %s = %.2f\n", (char)us_dollar_sym, pound, rate);
}
else if (choice == 1 && output == 4){
double dollar_yen_rate = 107.174;
rate = input * dollar_yen_rate;
System.out.printf( "%s" + input + " at a conversion rate of " + dollar_yen_rate + " Dollars to %s = %.2f\n", (char)us_dollar_sym, yen, rate);
}
if (choice == 2 && output == 1)
{
double euro_dollar_rate = 1.27579;
rate = input * euro_dollar_rate;
System.out.printf( "%s" + input + " at a conversion rate of " + euro_dollar_rate + " Euros to %s = %.2f\n", (char)euro_sym, us_dollar, rate);
}
else if (choice == 2 && output == 3)
{
double euro_pound_rate = 0.792648;
rate = input * euro_pound_rate;
System.out.printf( "%s" + input + " at a conversion rate of " + euro_pound_rate + " Euros to %s = %.2f\n", (char)euro_sym, pound, rate);
}
else if (choice == 2 && output == 4)
{
double euro_yen_rate = 136.708;
rate = input * euro_yen_rate;
System.out.printf( "%s" + input + " at a conversion rate of " + euro_yen_rate + " Euros to %s = %.2f\n", (char)euro_sym, yen, rate);
}
if (choice == 3 && output == 1)
{
double pound_dollar_rate = 1.60972;
System.out.printf( "%s" + input + " at a conversion rate of " + pound_dollar_rate + " Pounds to %s = %.2f\n", (char)pound_sym, us_dollar, rate);
}
else if (choice == 3 && output == 2)
{
double pound_euro_rate = 1.26161;
System.out.printf( "%s" + input + " at a conversion rate of " + pound_euro_rate + " Pounds to %s = %.2f\n", (char)pound_sym, euro, rate);
}
else if (choice == 3 && output == 4)
{
double pound_yen_rate = 172.511;
System.out.printf( "%s" + input + " at a conversion rate of " + pound_yen_rate + " Pounds to %s = %.2f\n", (char)pound_sym, yen, rate);
}
if (choice == 4 && output == 1)
{
double yen_dollar_rate = 0.00932574;
System.out.printf( "%s" + input + " at a conversion rate of " + yen_dollar_rate + " Yen to %s = %.2f\n", (char)yen_sym, us_dollar, rate);
}
else if (choice == 4 && output == 2)
{
double yen_euro_rate = 0.00730615;
System.out.printf( "%s" + input + " at a conversion rate of " + yen_euro_rate + " Yen to %s = %.2f\n", (char)yen_sym, euro, rate);
}
else if (choice == 4 && output == 3)
{
double yen_pound_rate = 0.00579135;
System.out.printf( "%s" + input + " at a conversion rate of " + yen_pound_rate + " Yen to %s = %.2f\n", (char)yen_sym, pound, rate);
}
System.out.println("Thank you for using the currency converter");
}
}