We Keep Coding

Trying to figure out how to pass array object data to a separate method

I wanted to write a program that records bar inventory as I'm a bartender. I can't figure out how to pass the liquorCost and liquorCount data to the GetCostTotal() method below the main() method. I'm absolutely sure it's something fairly straightforward that I'm doing incorrectly but I just can't figure it out. Any help is appreciated.
My Liquor class is separate and I can post that if necessary but I don't think it's the class that's giving me the problem, it's retrieving the data input from the array to the separate method.
package inventory;
import java.util.Scanner;
public class Inventory {
public static void main(String[] args) {
System.out.println("How many bottles are you taking inventory of?: ");
Scanner keyboard = new Scanner(System.in);
int size = keyboard.nextInt();
Liquor[] inv = new Liquor[size];
for (int i = 0; i < inv.length; i++) {
inv[i] = new Liquor();
System.out.println("Enter product name: ");
inv[i].setLiquorName(keyboard.next());
System.out.println("Enter the count for the product: ");
inv[i].setLiquorCount(keyboard.nextDouble());
System.out.println("Enter the cost for the product: ");
inv[i].setLiquorCost(keyboard.nextDouble());
}
System.out.println("The sitting inventory cost of these products is: ");
//double totalCost = 0
for (Liquor inv1 : inv) {
System.out.println(inv1.getLiquorName() + ": $" + inv1.getLiquorCost() * inv1.getLiquorCount());
}
double costTotal = GetCostTotal(Liquor[] inv, double liquorCost, double liquorCount);
System.out.println("The total cost of the inventory is: "
+ costTotal);
System.exit(0);
}
public static double GetCostTotal(Liquor[] inv, double liquorCost, double liquorCount) {
double costTotal = 0;
for ( int i = 0; i < inv.length; i++) {
costTotal += (liquorCost * liquorCount);
}
return costTotal;
}
}

try this
public static void main(String[] args) {
System.out.println("How many bottles are you taking inventory of?: ");
Scanner keyboard = new Scanner(System.in);
int size = keyboard.nextInt();
Liquor[] inv = new Liquor[size];
for (int i = 0; i < inv.length; i++) {
inv[i] = new Liquor();
System.out.println("Enter product name: ");
inv[i].setLiquorName(keyboard.next());
System.out.println("Enter the count for the product: ");
inv[i].setLiquorCount(keyboard.nextDouble());
System.out.println("Enter the cost for the product: ");
inv[i].setLiquorCost(keyboard.nextDouble());
}
System.out.println("The sitting inventory cost of these products is: ");
//double totalCost = 0
for (Liquor inv1 : inv) {
System.out.println(inv1.getLiquorName() + ": $" + inv1.getLiquorCost() * inv1.getLiquorCount());
}
double costTotal = GetCostTotal(inv);
System.out.println("The total cost of the inventory is: "
+ costTotal);
System.exit(0);
}
public static double GetCostTotal(Liquor[] inv) {
double costTotal = 0;
for ( int i = 0; i < inv.length; i++) {
costTotal += (inv[i].getLiquorCost() * inv[i].getLiquorCount());
}
return costTotal;
}

Lets understand what went wrong here.Take a look at how you are trying to call the GetCostTotal() method.
double costTotal = GetCostTotal(Liquor[] inv, double liquorCost, double liquorCount);
This is incorrect. The syntax/way you are calling the method is actually used when we what to define a method. Like you did:
public static double GetCostTotal(Liquor[] inv, double liquorCost, double liquorCount) {}
Your call should be like:
double costTotal = GetCostTotal(inv);
Here, we are passing only inv because the data for liquorCost and liquorCount is available inside "each" element of array inv.
Now you can accept this argument in GetCostTotal method. Here as you are iterating using a for loop, you can read the data you needed as inv[i].getLiquorCost() and inv[i].getLiquorCount().
I suggest you can read more on defining a method and calling a method in java.

Storing multiple values inside a while loop - Java

I'm trying to store the sum of 2 numbers inside a while loop so that once the loop ends multiple sums can be added up and given as a total sum, however I am rather new to Java and am not sure how to go about doing this.
I'm trying to use an array but I'm not sure if it is the correct thing to use. Any help would be greatly appreciated.
import java.util.Scanner;
public class StoredWhile{
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int TotalNum[]=new int[10];
Int Num1, Num2, AddedNum;
String answer;
do{
System.out.println("Please enter a number");
Num1 = input.nextInt();
System.out.println("Please enter a second number");
Num2 = input.nextInt();
AddedNum = Num1 + Num2;
System.out.println("The sum of the two entered numbers is " + AddedNum);
TotalNum[0]=AddedNum;
TotalNum[1]=;
System.out.println("Would you like to calculate the sum of two more numbers (y/n)?");
answer = input.next();
}
while (answer.equals("y"));
System.out.println("The total sum of all the numbers you entered is " + TotalNum);
}
}

There is a data container called ArrayList<>. It is dynamic and you can add as many sums as you need.
Your example could be implemented like this:
public class StoredWhile{
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
ArrayList<Integer> listOfSums = new ArrayList<>();
int Num1, Num2, AddedNum;
String answer;
do{
System.out.println("Please enter a number");
Num1 = input.nextInt();
System.out.println("Please enter a second number");
Num2 = input.nextInt();
AddedNum = Num1 + Num2;
System.out.println("The sum of the two entered numbers is " + AddedNum);
listOfSums.add(AddedNum);
System.out.println("Would you like to calculate the sum of two more numbers (y/n)?");
answer = input.next();
}
while (answer.equals("y"));
// Then you have to calculate the total sum at the end
int totalSum = 0;
for (int i = 0; i < listOfSums.size(); i++)
{
totalSum = totalSum + listOfSums.get(0);
}
System.out.println("The total sum of all the numbers you entered is " + totalSum);
}
}
From what I see, you come from a background of C# (Since I see capital letter naming on all variables). Try to follow the java standards with naming and all, it will help you integrate into the community and make your code more comprehensible for Java devs.
There are several ways to implement what you want, I tried to explain the easiest.
To learn more about ArrayList check this small tutorial.
Good luck!

Solution with array:
import java.util.Scanner;
public class StoredWhile{
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int TotalNum[]=new int[10];
int Num1, Num2, AddedNum;
String answer;
int count = 0;
do{
System.out.println("Please enter a number");
Num1 = input.nextInt();
System.out.println("Please enter a second number");
Num2 = input.nextInt();
AddedNum = Num1 + Num2;
System.out.println("The sum of the two entered numbers is " + AddedNum);
TotalNum[count]=AddedNum;
count++;
System.out.println("Would you like to calculate the sum of two more numbers (y/n)?");
answer = input.next();
}
while (answer.equals("y"));
int TotalSum = 0;
for(int i = 0; i <count; i++ ) {
TotalSum += TotalNum[i];
}
System.out.println("The total sum of all the numbers you entered is " + TotalSum);
}
}
This solution is not dynamic. There is risk that length of array defined on beginning will not be enough large.

How to pass variables from one method to another?

Trying to write a grade calculator program and am running into problems passing return variables from one method to another. I'm new to coding so I'm sure this isn't very pretty, but was hoping to get some help.
I have a method to calculate the Homework score, a method to calculate the midterm score, and a method to calculate the final score. I'm trying to call the return variables in the last method to calculate overall grade. The error is when calling the courseScore method, and displays as: The method courseScore(int, int, int) in the type GradeCalc is not applicable for the arguments (). Any help is appreciated!
import java.util.*;
public class GradeCalc {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int overAll;
int midtermScore;
int finalsScore;
hwpoints();
midTerm();
courseScore();
}
public static int hwpoints() {
int x;
int hwTotal = 0;
int pointsPossible = 0;
Scanner input = new Scanner(System.in);
System.out.println("Enter number of assignments:");
x = input.nextInt();
for(int i = 1; i <= x; i++) {
System.out.println("Enter assignment score:");
int hwScore = input.nextInt();
hwTotal += hwScore;
System.out.println("Enter total possible points:");
int points = input.nextInt();
pointsPossible += points;
}
int overAll = (hwTotal / x);
System.out.println("You got " + hwTotal + " out of " + pointsPossible + ". Your overall Homework grade is a: " + overAll);
return overAll;
}
public static int midTerm() {
int midtermPoints;
int midtermPossible;
int midtermScore;
Scanner input = new Scanner(System.in);
System.out.println("Enter Midterm Score:");
midtermPoints = input.nextInt();
System.out.println("Enter total possible Midterm Points:");
midtermPossible = input.nextInt();
midtermScore = (midtermPoints / midtermPossible);
System.out.println("Your Midterm score is " + midtermScore);
return midtermScore;
}
public static int finalScore() {
int finalsPoints;
int finalsPossible;
int finalsScore;
Scanner input = new Scanner(System.in);
System.out.println("Enter Finals Score:");
finalsPoints = input.nextInt();
System.out.println("Enter total possible Finals Points:");
finalsPossible = input.nextInt();
finalsScore = (finalsPoints / finalsPossible);
System.out.println("Your Finals score is " + finalsScore);
return finalsScore;
}
public static void courseScore(int finalsScore, int midtermScore, int overAll) {
Scanner input = new Scanner(System.in);
System.out.println("What percent of your grade is the final?");
int testWeight = input.nextInt();
System.out.println("What percent of your grade is the midterm?");
int midtermWeight = input.nextInt();
System.out.println("What percent of your grade is the homework?");
int hwWeight = input.nextInt();
int testWeighted = (finalsScore * (testWeight / 100));
int midtermWeighted = (midtermScore * (midtermWeight / 100));
int hwWeighted = (overAll * (hwWeight / 100));
int courseScore = ((hwWeighted + midtermWeighted + testWeighted) * 100);
System.out.println("Your total course grade is " + courseScore);
}
}

The methods hwpoints, midTerm and finalScore all return an int value which you are not keeping
You need to do some thing like
int hwp = hwpoints ();
int mt = midterm ();
int fs = finalScoare ();
then you can pass these variable into courseScore as
courseScore (fs, mt, hwp);
Note
In this code
int testWeighted = (finalsScore * (testWeight / 100));
you are going to be undertaking integer division.
See Int division: Why is the result of 1/3 == 0?

First thing is to understand the concept of a class and a static method.
Classes have fields and methods.
Fields (variables) hold data (state) that the Methods can operate on
Each instance of a class has its own values for these fields
Methods operate on the Fields
Methods can include call parameters
Methods can also return a value
Static instances (classes, fields, and methods) are singletons
There is only one copy of them (all instances of the class share the same one)
Static Methods cannot access (non-static) fields/methods
Using this, consider creating another class that has (most) of the content of your GradeCalc class and remove the statics from them and create an instance of that class in GradeCalc. That way each method in the class can access the fields you have defined.
Here is an example of the concept based on what you have already written.
Note: You code has other structural/implementation issue and I would never implement it as shown; but, I don't want to turn this into a Java course; so, I tried to show you something that could work within the context of what you had written.
public class GradeCalc {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
Calculator calc = new Calculator (calc);
calc.hwpoints();
calc.midTerm();
calc.courseScore();
int overAll = calc.OverAll;
int midtermScore = calc.MidtermScore;;
int overAll = calc.OverAll;
}
public class Calculator {
public void OverAll;
public void MidtermScore;
public void FinalsScore;
public void hwpoints()
{
...
OverAll = overAll
}
//Do the same for the methods below
//public void midTerm();
//public void courseScore();
}

returning a void method in my main method

My question is based on returning a Void method on my main method in java the following its my code. Where am I doing wrong?
package practiceq3;
import java.util.Scanner;
public class Practiceq3 {
public void FutureInvestmentValue(double InvestmentAmount, double MontlyInvestmentRate, int Years)
{
System.out.printf("%-5s %s \n", "Years", "Investment Value");
//For loop
int i;
int y;
for(i = 1; i <= Years; i++)
{
for (y = 1; y <= 12; y++)
{
InvestmentAmount += (InvestmentAmount * MontlyInvestmentRate);
System.out.printf("%-5d %2f \n", i , InvestmentAmount);
}
}
}
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.print("Enter the Investment Amount: ");
double InvestmentAmount = input.nextDouble();
System.out.print("Enter the Montly investment rate: ");
double MontlyInvestmentRate = input.nextDouble();
System.out.print("Enter the Years: " );
int Years = input.nextInt();
Practiceq3 m = new Practiceq3();
// Compilation error here:
System.out.printf("Investment Value is $%2f", m.FutureInvestmentValue(input.nextDouble(),(input.nextDouble()/1200), Years));
input.close();
}
}
The compilation fails with the error:
Error:(34, 78) java: 'void' type not allowed here

Your method FutureInvestmentValue doesn't return any value, but you are trying to print the (missing) return value from this method:
System.out.printf("Investment Value is $%2f", m.FutureInvestmentValue(...));
Looking over your code, it's not quite clear how exactly should the method FutureInvestmentValue behave - it seems to print the calculated information itself.
Probable solutions would be either:
System.out.println("Investment Value is:");
m.FutureInvestmentValue(...); // Prints the calculated data itself
Leave the System.out.printf line in the main method unchanged and modify the FutureInvestmentValue to return some value instead of printing it.

You'll need to do one of two things: either return the result from your method or instead of return value, print out the method parameter that you used to store the result.
So either change your FutureInvestmentValue method like this:
public double FutureInvestmentValue(double InvestmentAmount, double MontlyInvestmentRate, int Years)
{
// skip other stuff
return InvestmentAmount;
}
or change your main method to something like this:
double value = input.nextDouble();
m.FutureInvestmentValue(value, value/1200, Years);
System.out.printf("Investment Value is $%2f", value);

As mentioned by Alex FutureInvestmentValue method is void and hence you are getting error. If you want to print theinvestmentValue in print statement then change the return type of method to double and return InvestmentAmount variable value.

i managed to answer this question the way the question requested but i also considered what you guys said and at the end i managed to see my mistakes in my code so the following is my answer for the question
import java.util.Scanner;
public class ClassA {
public static void main(String[] args) {
try (Scanner input = new Scanner(System.in)) {
ClassB con = new ClassB();//this is the object of the class
System.out.print("Enter the Investment Amount: ");
double investmentAmount = input.nextDouble();
System.out.println();
System.out.print("Enter the Montly investment rate: ");
double montlyInvestmentRate = input.nextDouble();
System.out.println();
System.out.print("Enter the Years: ");
int years = input.nextInt();
System.out.println();
//this is where we call our void method FutureInvestmentValue(double InvestmentAmount, double MontlyInvestmentRate, int Years)
con.FutureInvestmentValue(investmentAmount ,(montlyInvestmentRate/1200), years);
}
}
}
public class ClassB {
public void FutureInvestmentValue(double InvestmentAmount, double MontlyInvestmentRate, int Years)
{
System.out.printf("%-5s %s \n", "Years", "Future Value");
//For loop
int i;
double Fv;
for(i = 1; i <= Years; i++)
{
//Future value formular A=P(1+i/m)^n*m
Fv = (InvestmentAmount * Math.pow(1+MontlyInvestmentRate,i*12));
System.out.printf("%-5d %.2f \n", i , Fv);
}
}
}

Why doesn't my array work?

I'm very new to java (only been using it for 2 days now), and am trying to make a class that lets you input three numbers, and then outputs the average of all three. When the code is like this the output always equals 0 and I don't know why? I am able to get it to work if I change add "static" to all the public integers, but why do I have to do that? Is there another way I can do it without making them static?
import java.util.Scanner;
public class lettuce
{
public int num1;
public int num2;
public int num3;
public static void main(String args[])
{
lettuce lettuceObject = new lettuce();
int total = 0;
int average;
int array[] = {lettuceObject.num1,lettuceObject.num2,lettuceObject.num3};
lettuceObject.getNum1();
System.out.println(lettuceObject.num1);
System.out.println(array[0]);
lettuceObject.getNum2();
System.out.println(lettuceObject.num2);
System.out.println(array[1]);
lettuceObject.getNum3();
System.out.println(lettuceObject.num3);
System.out.println(array[2]);
for(int counter = 0; counter < array.length;counter++)
{
total = total + array[counter];
}
average = total/array.length;
System.out.println("The average of the three numbers is: " + average);
}
public int getNum1()
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Please type your first number: ");
return num1 = keyboard.nextInt();
}
public int getNum2()
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Please type your second number: ");
return num2 = keyboard.nextInt();
}
public int getNum3()
{
Scanner keyboard = new Scanner(System.in);
System.out.println("Please type your third number: ");
return num3 = keyboard.nextInt();
}
}

The output is 0 because you have never initialized your num(s), you're assigning to them on get(s) which you never call - and you're trying to set them in get(s) which isn't the customary approach.
public int num1 = 3;
public int num2 = 3;
public int num3 = 3;
And you should get 3. A getter should look like
public int getNum1()
{
return num1;
}
A setter should look like
public void setNum1(int num1) {
this.num1 = num1;
}
And then you would customarily name your class Lettuce and call it from main like
Lettuce lettuce = new Lettuce();
lettuce.setNum1(10);
System.out.println(lettuce.getNum1());
You would customarily also make your fields private and access them through your mutator and accessor methods (getters and setters)
private int num1;
private int num2;
private int num3;
You could choose to create a constructor
public Lettuce(int num1, int num2, int num3) {
this.num1 = num1;
this.num2 = num2;
this.num3 = num3;
}
You could also calculate the average from "lettuce" with something like
public double average() {
return (num1 + num2 + num3) / 3.0;
}
Edit
Please don't edit your question like that. Also, consider the order of your operations. Your get methods are what set the values. So call them before you create your array!
lettuceObject.getNum1();
lettuceObject.getNum2();
lettuceObject.getNum3();
// Each of those values is 0 until you call the previous three lines.
int array[] = {lettuceObject.num1,lettuceObject.num2,lettuceObject.num3};
System.out.println(array[0]);
System.out.println(array[1]);
System.out.println(array[2]);

As you are new I will give you some more tips they making this work.
1: The static modifier specifies that you don't need to instanciate a Class to use that attribute (variable or method ).
For example, if you have a class with one static variable:
public class Clazz {
static int variable=1;
}
You may call it without creating an instance of Clazz. System.out.println(Clazz.variable); would compile with no problems.
Otherwise, a non-staticattribute will need an Instance of Clazz to be accessed:
Clazz instanceOfClazz = new Clazz();
System.out.println(instanceOfClazz.variable);
2: The type intis native. So, when you create your array, you are passing no values, and after reading the output, your array is not updated.
3: a double variable would be more precise to store the result of an average.
4: last but not least, your getNum method could be merged into just 1 method receiving the message as parameter, so you hace a best and clear reuse of the code. That can be staticbecause it doesn't need to interact with any object of the class Lettuce (with receive as parameter all it needs to execute and return the integer sent by the user, you can assing the return outside the method)
Ps.: by notation, the class name should start with capital letter.
Your final class would look better this way:
import java.util.Scanner;
public class Lettuce
{
public int num1;
public int num2;
public int num3;
public static void main(String args[])
{
Lettuce lettuceObject = new Lettuce();
int total = 0;
double average;
lettuceObject.num1 = lettuceObject.getNum("Please type your first number: ");
System.out.println(lettuceObject.num1);
System.out.println(array[0]);
lettuceObject.num2 = lettuceObject.getNum("Please type your second number: ");
System.out.println(lettuceObject.num2);
System.out.println(array[1]);
lettuceObject.num2 = lettuceObject.getNum("Please type your third number: ");
System.out.println(lettuceObject.num3);
System.out.println(array[2]);
int array[] = {lettuceObject.num1,lettuceObject.num2,lettuceObject.num3};
for(int counter = 0; counter < array.length;counter++)
{
total = total + array[counter];
}
average = total/array.length;
System.out.println("The average of the three numbers is: " + average);
}
public int getNum(String message)
{
Scanner keyboard = new Scanner(System.in);
System.out.println(message);
return keyboard.nextInt();
}
}
Hope this helped.