I'm struggeling a bit with arrays and user what's inside with loops. I have this question for example (ignore what's inside of the previewOrder method, i was trying stuff out):
public class Ex1_19 {
final static String NAMES[]= {"Spa reine 25 ","Bru plate 50","Bru pét 50",
"Pepsi","Spa orange", "Schweppes Tonic","Schweppes Agr","Ice Tea","Ice Tea Pêche",
"Jus d'orange Looza", "Cécémel", "Red Bull","Petit Expresso","Grand Expresso","Café décaféiné ",
"Lait Russe ","Thé et infusions","Irish Coffee ","French Coffee ","Cappuccino","Cécémel chaud",
"Passione Italiano","Amour Intense", "Rhumba Caliente ","Irish Kisses ","Cuvée Trolls 25",
"Cuvee Trolls 50","Ambrasse-Temps 25","Ambrasse-Temps 50 ","Brasse-Temps Cerises 25",
"Brasse-Temps Cerises 50","La Blanche Ste Waudru 25","Blanche Ste Waudru 50",
"Brasse-Temps citr 25","Brasse-Temps citr 50","Spaghetti Bolo ","Tagl Carbonara",
"Penne poulet baslc ","Tagl American","Tagl saum"};
final static double NETPRICES[]= {2.2, 2.3,3.9,2.2,2.2,2.6,2.6,2.6,2.6,2.6,2.6,4.5,2.2,2.2,2.2,2.5,2.5,7.0,7.0,2.8,2.8,6.2,6.2,6.2,6.2,
2.9,5.5,2.7,5.1,3.1,5.8,2.6,4.9,2.6,4.9,10.8,11.2,12.2,14.5,16.9};
public static void main(String[] args) {
int Order[][]={{3,2},{1,3},{12,4},{37,1},{36,3},{0,0},{0,0},{0,0}, {0,0}};
previewOrder(Order);
}
public static void previewOrder(int order[][]) {
int i = 0;
int j = 0;
while(i < order.length && j < order.length) {
System.out.println(NAMES[i]);
i++;
j++;
}
}
}
My result has to be something like this but with what's inside the "order" array:
Bru pét 50 3.9 2 7,80
Spa reine 25 2.2 3 6,60
Red Bull 4.5 4 18,00
Tagl Carbonara 11.2 1 11,20
Spaghetti Bolo 10.8 3 32,40
In my exercice I have to use a while loop and I have to put the order array in my method parameters. I can't figure out how to make them all communicate.
Sorry if this question has been answered somewhere else but I don't know how to search for it.
EDIT: I know that Orders does not use zero based index, but starts at 1. This is probably because "Order" is supposed to be a user entry. The first number of the array is like a drink number.
I wasn't very clear on the expected output.
Bru pét 50 (NAME[3]) 3.9 (NETPRICE[3]) 2 (Order[][2]) 7.80 NETPRICE[3] * Order[][2] and this for every occurence in Order
The Order array (btw: should be named order or orders) obviously contains references to ordered items and their amount. It's a two dimensional array, like a table with two columns.
Your expected output of "Bru pét 50 3.9 2 7,80", coming from Order[0] {3,2} indicates that the first element (Order[0][0]) is a reference to the items name (from NAMES) and the price (from NETPRICES). The second value of each "row" is the item amount (2) and finally there's the computed total.
For reasons unknown, Orders does not not use zero-based indexed, but starts at 1. So ORDER[0] having value {3,2} actually referes to NAMES[2] and NETPRICES[2]. This needs to be taken into account when picking the right item form NAMES and NETPRICES.
Anyhow: This is what your method could look like. You still need to tweak the output according to your needs.
public static void previewOrder(int order[][]) {
for (int i = 0; i < order.length; i++) {
int index = order[i][0] - 1;
if (index < 0 || index > NAMES.length || index > NETPRICES.length) {
continue;
}
String name = NAMES[order[i][0] - 1];
double price = NETPRICES[order[i][0] - 1];
int amount = order[i][1];
double total = amount * price;
System.out.println(
name + " " + price + " " + amount + " " + total
);
}
}
Try this.
public static void previewOrder(int order[][]) {
Stream.of(order)
.filter(x -> x[0] != 0)
.forEach(x -> {
String name = NAMES[x[0] - 1];
int unit = x[1];
double price = NETPRICES[x[0] - 1];
System.out.printf("%s %.1f %d %.2f%n",
name, price, unit, price * unit);
});
}
output:
Bru p?t 50 3.9 2 7.80
Spa reine 25 2.2 3 6.60
Red Bull 4.5 4 18.00
Tagl Carbonara 11.2 1 11.20
Spaghetti Bolo 10.8 3 32.40
or
public static void previewOrder(int order[][]) {
for (int[] row : order) {
if (row[0] == 0)
continue;
String name = NAMES[row[0] - 1];
int unit = row[1];
double price = NETPRICES[row[0] - 1];
System.out.printf("%s %.1f %d %.2f%n",
name, price, unit, price * unit);
}
}
When I see tightly coupled arrays, I think of creating a class.
public class Product {
String name;
double unitPrice;
public Product () {
name = "*** Unnamed Product ***";
unitPrice = 0.0;
}
public Product (String name, double unitPrice) {
this.name = name;
this.unitPrice = unitPrice;
}
public String getName () { return name; }
public double getPrice () { return unitPrice; }
public String toString () { return name + " # " + unitPrice + " ea.";}
}
Then, you can have one array where you previously had two:
public class Ex1_19 {
static final Product [] productList = {
new Product("Spa reine 25 ", 2.2),
new Product("Bru plate 50", 2.3),
new Product("Bru pét 50", 3.9),
new Product("Pepsi", 2.2),
new Product("Spa orange", 2.2),
new Product("Schweppes Tonic", 2.6),
new Product("Schweppes Agr", 2.6),
new Product("Ice Tea", 2.6)
// and so on
};
}
The preview order method, without formatted output, might look like this:
public static void previewOrder (int[][] order) {
double total = 0.0;
double itemCount = 0;
int lineNum = 0;
for (int i = 0; i < order.length; ++i) {
int row = order[i][0] - 1;
if (row < 0) {
break;
}
int qty = order [i][1];
double amt = productList [row].getPrice () * qty;
System.out.println (++lineNum + " " + productList[row].getName()
+ " " + productList[row].getPrice () + " " + qty
+ " " + amt);
itemCount += qty;
total += amt;
}
System.out.println ("===\nTotal: " + total + " for " + itemCount + " items.");
}
So i'd like to align the row that displays the tenth year with rest of the numbers.
I've tried printf but it doesn't seem to work.
I've looked at many posts already but everything seems to be roaming around printf with some string formats.
If you can juste explain how to do it to me with some examples it would help me a lot.
Thanks for the help.
public class Foo {
public static void main(String[] args) {
double capitalDeDepart = capitalDepart(0);
double tauxInteretAnnuel = interetAnnuel(0);
double anneeTotalPlacement = dureePlacement(0);
affichage();
calcul(capitalDeDepart, tauxInteretAnnuel, anneeTotalPlacement);
}
public static double capitalDepart(double capitalDeDepart) {
Scanner clavier = new Scanner(System.in);
System.out.print("Indiquez le capital de départ : ");
capitalDeDepart = clavier.nextDouble();
return capitalDeDepart;
}
public static double interetAnnuel(double tauxInteretAnnuel) {
Scanner clavier = new Scanner(System.in);
System.out.print("Inscrivez le taux d'intérêt annuel : ");
tauxInteretAnnuel = clavier.nextDouble();
return tauxInteretAnnuel;
}
public static double dureePlacement(double anneeTotalPlacement) {
Scanner clavier = new Scanner(System.in);
System.out.print("Indiquez la durée du placement en années : ");
anneeTotalPlacement = clavier.nextDouble();
return anneeTotalPlacement;
}
public static void affichage() {
System.out.println("Année Capital Intérêt Nouveau capital");
System.out.println("----------------------------------------------");
}
public static void calcul(double capitalDeDepart, double tauxInteretAnnuel, double anneeTotalPlacement) {
int annee = 0;
double interet = 0;
double nouveauCapital = 0;
double tauxEnDecimal = 0;
do {
annee++;
capitalDeDepart = capitalDeDepart + interet;
tauxEnDecimal = tauxInteretAnnuel / 100;
interet = capitalDeDepart * tauxEnDecimal;
nouveauCapital = (int)(capitalDeDepart + interet);
System.out.println(" " + annee + " " + (int)capitalDeDepart + "$ " + (int)interet + "$ " + (int)nouveauCapital + "$");
} while (annee != anneeTotalPlacement);
}
}
Indiquez le capital de départ : 10000
Inscrivez le taux d'intérêt annuel : 10
Indiquez la durée du placement en années :
Année Capital Intérêt Nouveau capital
----------------------------------------------
1 10000$ 1000$ 11000$
2 11000$ 1100$ 12100$
3 12100$ 1210$ 13310$
4 13310$ 1331$ 14641$
5 14641$ 1464$ 16105$
6 16105$ 1610$ 17715$
7 17715$ 1771$ 19487$
8 19487$ 1948$ 21435$
9 21435$ 2143$ 23579$
10 23579$ 2357$ 25937$
Just replase your System.out.println(...) with following:
System.out.format("%2d %5d$ %5d$ %5d$\n", annee,
(int)capitalDeDepart, (int)interet, (int)nouveauCapital);
you must will try add a String variable... like...
String reglerAnnee;
...
// add a space if year(anne) is less than 10
// using a ternary operator, like an "if" but less code
reglerAnnee = annee < 10 ? " " : "";
..
// and add to the println ...
System.out.println(" "+reglerAnnee + annee + " " + (int) capitalDeDepart
+ "$ " + (int) interet + "$ "
+ (int) nouveauCapital + "$");
...
The result will be like:
1 10000$ 1000$ 11000$
2 11000$ 1100$ 12100$
...
9 21435$ 2143$ 23579$
10 23579$ 2357$ 25937$
I'm having a bit of an issue with a school project of mine. We're supposed to write a Loan class that will do things associated with, well, loans, such as return the monthly payment and the total payment on the loan. My problem is that I have specific instructions for this code that I absolutely cannot go outside of.
Here's the code:
import java.util.Scanner;
import java.text.DecimalFormat;
import java.lang.Math;
public class Loan
{
public double annualInterestRate = 0;
public int numberOfYears = 0;
public double loanAmount = 0;
public Loan()
{
annualInterestRate = 0.025;
numberOfYears = 1;
loanAmount = 1000;
}
public Loan(double interestRate, int numYears, double amount)
{
setRate(interestRate);
setYears(numYears);
setLoanAmount(amount);
}
public void setRate(double interest)
{
DecimalFormat percent = new DecimalFormat( "0.0%" );
if(interest > 25 || interest < 0)
{
System.out.println("WARNING: Invalid annual interest rate: " + percent.format(interest) + ".");
System.out.println("Current value not changed: " + percent.format(annualInterestRate * 100) + ".");
}
else
{
annualInterestRate = interest;
}
}
public void setYears(int years)
{
if(years > 30 || years <= 0)
{
System.out.println("WARNING: Invalid number of years: " + years + ".");
System.out.println("Current value not changed: " + numberOfYears + ".");
}
else
{
numberOfYears = years;
}
}
public void setLoanAmount(double amnt)
{
DecimalFormat loan = new DecimalFormat( "$#,##0.00" );
if(amnt <= 0)
{
System.out.println("WARNING: Invalid loan amount: " + loan.format(amnt) + ".");
System.out.println("Current value not changed: " + loan.format(amnt) + ".");
}
else
{
loanAmount = amnt;
}
}
public double getAnnualInterestRate()
{
return annualInterestRate;
}
public int getNumberOfYears()
{
return numberOfYears;
}
public double getLoanAmount()
{
return loanAmount;
}
public double getMonthlyPayment()
{
double monthly = annualInterestRate/12;
double monthlyPayment = (loanAmount * monthly)/1 - (1/(1 + monthly));
monthlyPayment = Math.pow(monthlyPayment, 12);
return monthlyPayment;
}
public double getTotalPayment()
{
double totalPayment = getmonthlyPayment() * 12;
return totalPayment;
}
public String toString()
{
DecimalFormat percent = new DecimalFormat( "0.0%" );
DecimalFormat loan = new DecimalFormat( "$#,##0.00" );
String interestRate = percent.format(annualInterestRate);
String numOfYears = Integer.toString(numberOfYears);
String loanAmnt = loan.format(loanAmount);
String total = "Annual Interest Rate:\t" + interestRate + "\nNumber of Years:\t\t" + numOfYears + "\nLoan Amount:\t\t\t" + loanAmnt;
return total;
}
}
My problem is with the getTotalPayment method. It can't access the monthlyPayment variable without me either declaring monthlyPayment as a field, like annualInterestRate, or passing it to the getTotalPayment method. The issue is, getTotalPayment is not allowed to have parameters, and we aren't allowed to have any more fields than the three she instructed us to have, which are the three you'll see declared in the beginning of the code.
So, my question: is there a way to make the variable monthlyPayment accessible to getTotalPayment, without making monthlyPayment a field or giving getTotalPayment a parameter?
You have a spelling error in your getTotalPayment() method.
What your trying to do is call the method getmonthlyPayment() when you should be calling getMonthlyPayment().
Incase you missed the suttle difference in my answer you have a lowercase 'm' when you want an uppercase 'M'.
Im not entirety sure if this is your problem, but its the only syntax error my IDE is telling me.
In your revised code you need upper case M in call to getMonthlyPayment().
EDIT: HERE IS A SCREENSHOT OF THE OUTPUT
https://www.dropbox.com/s/93d09a627se3b1u/Screenshot%202015-09-16%2019.08.19.png?dl=0]
I was recently asked to make a program that can calculate and display...
1 / (1!) + 1 / (2!) + . . . 1 / (n!)
using the Scanner utility. I seem to be having a lot of trouble with this. the program itself works, but it somehow gives the same answer no matter what number I input. Here's what I have so far (And yes, it is purposely incomplete, I'm stumped).
import java.util.Scanner;
class Power2
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.println("I will calculate 1/(1!) + 1/(2!) . . . +
1/(n!)\nWhat is the value of n?");
Double n = input.nextDouble();
Math(n);
System.out.println("e = " + Math.E);
}
public static void Math(Double E)
{
Double product = 1.0;
int x = 0;
while (E > 0)
{
product = product * E;
E--;
}
Can anyone give me a way to finish/solve this problem? Thanks a ton.
~Andrew
EDIT: This code works fine for just finding the extreme. I will work on a way to add the preceding components of the equation to this, but It's a bit tricky for me.
import java.util.Scanner;
class Power2
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.println("I will calculate 1/(1!) + 1/(2!) . . . +
1/(n!)\nWhat is the value of n?");
Double n = input.nextDouble();
Math(n);
System.out.println("e = " + Math(n));
}
public static Double Math(Double E)
{
Double product = 1.0;
while (E > 0)
{
product *= E;
E--;
}
return product;
}
}
You are confused with too much Math.
You've got your method Math with a parameter E and the Java Math class with a constant E. You're mixing them up.
Try
public static double factorial(double v)
{
double product = 1.0;
while (v > 0)
{
product *= v;
v--;
}
return product;
}
Your code:
System.out.println("e = " + Math.E);
Math.E is a constant - it will always print the euler number hence your output.
To call the the method correctly it should be
System.out.println("e = " + math(e)"
Input 1 - Output 1
Input 2 - Output 1.5
Input 3 - Output 1.66666667
import java.util.Scanner;
class MyClass
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.println("I will calculate 1/(1!) + 1/(2!) . . . + 1/(n!)\nWhat is the value of n?");
double n = input.nextDouble();
double solution = doMath(n);
System.out.println("e = " + solution);
}
public static double doMath(double n) {
double ret = 0;
// the number of terms we add
for (int i = 1; i <= n; i++) {
ret += calcFaculty(i);
}
return ret;
}
// calculate every single term
public static double calcFaculty(double d){
double calc = 1;
for (int i = 1; i <= d ; i++) {
calc = calc* 1/i;
}
return calc;
}
}
Hi Andrew the program always return the same number
e = 2.718281828459045
Because the line System.out.println("e = " + Math.E); is not calling the method Math but calling to the class java.lang.Math. I dont know if is this what you find dubious.
I'm in an intro programming class, in the lab that I'm currently working on we have to have two classes and pull the methods from one class, "Energy" and have them run in "Energy Driver."
I'm having trouble calling the methods (testOne, testTwo, testThree) over into "EnergyDriver"
public class EnergyDriver
{
public static void main(String [] args)
{
System.out.println(mass1 + " kiolograms, " + velocity1 +
"meters per second: Expected 61250," + " Actual " + kineticE1);
System.out.println(mass2 + " kiolograms, " + velocity2 +
"meters per second: Expected 61250," + " Actual " + kineticE2);
System.out.println(mass3 + " kiolograms, " + velocity3 +
"meters per second: Expected 61250," + " Actual " + kineticE3);
}
}
public class Energy
{
public static void main(String [] args)
{
public double testOne;
{
double mass1;
double velocity1;
double holderValue1;
double kineticE1;
mass1 = 25;
velocity1 = 70;
holderValue1 = Math.pow(velocity1, 2.0);
kineticE1 = .5 *holderValue1 * mass1;
}
public double testTwo;
{
double mass2;
double velocity2;
double holderValue2;
double kineticE2;
mass2 = 76.7;
velocity2 = 43;
holderValue2 = Math.pow(velocity2, 2.0);
kineticE2 = .5 *holderValue2 * mass2;
}
public double testThree;
{
double mass3;
double velocity3;
double holderValue3;
double kineticE3;
mass3 = 5;
velocity3 = 21;
holderValue3 = Math.pow(velocity3, 2.0);
kineticE3 = .5 *holderValue3 * mass3;
}
}
You must have only one main method in any one of class. To call a method from another class you can create an object of that class a call their respective method. Another way is by keeping the calling method to be static so you can access that method via Classname.Methodname.
public class EnergyDriver
{
public static void main(String [] args)
{
Energy energy=new Energy();
System.out.println(mass1 + " kiolograms, " + velocity1 +
"meters per second: Expected 61250," + " Actual " + energy.testOne());
System.out.println(mass2 + " kiolograms, " + velocity2 +
"meters per second: Expected 61250," + " Actual " + energy.testTwo());
System.out.println(mass3 + " kiolograms, " + velocity3 +
"meters per second: Expected 61250," + " Actual " + energy.testThree());
}
}
class Energy
{
public double testOne()
{
double mass1;
double velocity1;
double holderValue1;
double kineticE1;
mass1 = 25;
velocity1 = 70;
holderValue1 = Math.pow(velocity1, 2.0);
kineticE1 = .5 *holderValue1 * mass1;
return kineticE1;
}
public double testTwo()
{
double mass2;
double velocity2;
double holderValue2;
double kineticE2;
mass2 = 76.7;
velocity2 = 43;
holderValue2 = Math.pow(velocity2, 2.0);
kineticE2 = .5 *holderValue2 * mass2;
return kineticE2;
}
public double testThree()
{
double mass3;
double velocity3;
double holderValue3;
double kineticE3;
mass3 = 5;
velocity3 = 21;
holderValue3 = Math.pow(velocity3, 2.0);
kineticE3 = .5 *holderValue3 * mass3;
return kineticE3;
}
}
You can get the value of Kinetic Engergy 1,2,3 by using this code.
You can also use the below code which will use only one method to calculate different values by giving different arguments.
public class EngergyDriver
{
public static void main(String [] args)
{
Energy energy=new Energy();
double mass=25;
double velocity=70;
System.out.println(mass+ " kiolograms, "+velocity+"meters per second: Expected 61250," + " Actual " + energy.testOne(mass,velocity));
}
}
class Energy
{
public double testOne(double mass, double velocity)
{
double mass1;
double velocity1;
double holderValue1;
double kineticE1;
mass1 = 25;
velocity1 = 70;
holderValue1 = Math.pow(velocity1, 2.0);
kineticE1 = .5 *holderValue1 * mass1;
return kineticE1;
}
}
Java programs have SINGLE point of entry and that is through the main method.
Therefore in a single project only one class should have the main method and when compiler will look for that when you run it.
Remember that static methods cannot access non static methods hence main is static therefore it can not access testone two nor three UNLESS you create and object of that type. Meaning in the main method you can have Energy e = new Energy() then access those methods that were not declared with keyword static like e.testone() .
However take note that non static methods can access static methods through Classname.Method name because keyword static entails that only a single copy of that method/variable exists therefore we do not need an object to access it since only one copy exists.
I recommend watching the Java videos from Lynda.com or reading the books Java Head First and Java How To Program (Deitel,Deitel) to give you a boost on your Java knowledge they come with alot of exercises to enhance your knowledge.
Also there are plenty of other questions like this on SO search for them