I am currently learning Java and following some online tutorials. One of the assignments is to compute the body age of a person by getting their various scores, getting the average of these scores and then applying a formula to it to get the total. I can do it with one big class, but the assignment then asks to go further and split everything into different classes. My program currently looks like this:
import java.util.Scanner;
public class fit2 {
public static void main(String[] args) {
int average, bodyAge;
average = average2();
System.out.println(average);
bodyAge = fitAge();
System.out.println(bodyAge);
}
public static int fs() {
int fs;
System.out.println("Enter first number: ");
Scanner bucky = new Scanner(System.in);
fs = bucky.nextInt();
return fs;
}
public static int ss() {
int ss;
System.out.println("Enter second number: ");
Scanner bucky = new Scanner(System.in);
ss = bucky.nextInt();
return ss;
}
public static int average2() {
int first, second, average;
first = fs();
second = ss();
average = (first + second) / 2;
return average;
}
public static int fitAge() {
int fitAge, average;
average = average2();
fitAge = average * 8 / 5 + 10;
return fitAge;
}
}
My idea was to have different methods for each part of the program - two methods to get the users scores and then pass these into a averageing method, which would then pass it into a final method which would apply the formula, then passing it back it into the Main class, which would print that age out as well as the Average age.
I read somewhere that you shouldnt get user input in classes but get it in main and pass it into the average class using parameters -- can anyone advise on this?
Thanks.
Try something like this (as suggested by my comment on the question):
import java.util.Scanner;
public class fit2 {
public static void main(String[] args) {
System.out.println("Enter first number: ");
Scanner bucky = new Scanner(System.in);
int fs = bucky.nextInt();
System.out.println("Enter second number: ");
bucky = new Scanner(System.in);
int ss = bucky.nextInt();
int average = average2(fs, ss);
int bodyAge = fitAge(average);
System.out.println(average);
System.out.println(bodyAge);
}
public static int average2(int first, int second) {
int average;
average = (first + second) / 2;
return average;
}
public static int fitAge(int average) {
int fitAge;
fitAge = average * 8 / 5 + 10;
return fitAge;
}
}
I believe I understand your question - you are unsure of where to place user input in your program.
In a small program like this, it may be wise to place user input in the main() method, solely because you gather user input, delegate input to methods that perform computation on the data that is "under the hood" of the program, and then return the value back to the user.
In your specific instance, this seems like a wise decision, as your program is small and a standard console-based application. This may not always be the case in the future, depending on the program you are writing.
Realistically, it doesn't matter all too much if it runs as intended, but for simplicity sake (remember KISS) putting user input in your main() method is probably a good idea.
Related
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();
}
I have created a simple class which calculates the win/loss percentage and returns the amount of necessary consecutive wins to obtain the desired win/loss percentage of the given input from the user, based on the given values of wins, loss, and desired win/loss. However, whilst running the program, I notice the output gives an exceedingly large number in the place of what should be a relatively small number (the number of wins needed). I am not certain what error I have made that created this, but I'm certain it's relative to the while loop located in my howManyToWinLoss() method, or perhaps some error I've made in the tester class's output. At any rate, they are both located below, and I appreciate the assistance:
public class WinLossCalculator
{
private int win;
private int loss;
private int totalGames;
private double desiredWinLoss;
private double winLoss;
private int gamesToDWL;
public WinLossCalculator(int w, int l, double dwl)
{
win = w;
loss = l;
totalGames = w + l;
desiredWinLoss = dwl;
}
public double winPercent()
{
return winLoss = (double)win/(double)totalGames;
}
public double lossPercent()
{
return (double)loss/(double)totalGames;
}
public int howManyToWinloss()
{
int x = 0;
while(winLoss < desiredWinLoss)
{
winLoss = (win+x)/(win+x+loss);
if(winLoss < desiredWinLoss)
{
x++;
}
}
return gamesToDWL = x;
}
}
and
import java.util.*;
public class WinLossTester
{
public static void main(String []args)
{
Scanner in = new Scanner(System.in);
System.out.print("Enter the amount of matches you've won: ");
int wins = in.nextInt();
System.out.print("\nEnter the amount of matches you've lost: ");
int losses = in.nextInt();
System.out.print("\nEnter your desired match win percentage (eg. 75.4): ");
double desiredWLP = in.nextDouble();
System.out.println();
WinLossCalculator one = new WinLossCalculator(wins, losses, (desiredWLP / 100));
one.winPercent();
one.howManyToWinloss();
System.out.printf("Win percentage: %6.1f", (one.winPercent()*100));
System.out.print("%");
System.out.printf("\nLoss percentage: %5.1f", (one.lossPercent()*100));
System.out.print("%");
System.out.println("\nVictories required to reach desired W/L percent (without loss): " + one.howManyToWinloss());
}
}
Additionally--I feel as though my tester class's output section is a little ugly, might anyone have any suggestions concerning formatting or cleaning up the code in the output section?
Ok, apparently it has to do with me not casting the first line in my for loop to double like this winLoss = (double)(win+x)/(double)(win+x+loss); I don't know why that broke it, but, that's why it was broken.
Need some help trying to set up this assignment. I am not to good with arrays, nor setting up methods to be used in the main. I need to make an array of 10 random numbers 1-100, that can be compared to the user input. I only need the comparison true/false to display. Here is what I have.
I get several errors in trying to print, so i haven't even tried to compare it to the user input yet.
Thanks,
import java.util.*;
public class Final {
public static void main(String[] args) {
System.out.print("Enter Player's Free Throw Percentage: ");
Scanner input = new Scanner(System.in);
int percent = input.nextInt();
print(shots);
}
public int [] getRandomNumbers(){
int [] shots = new int [10];
Random r = new Random();
for(int i = 0; i < 10; i++)
shots[i] = r.nextInt(100);
return shots;
}
public static void print(int shots[]) {
for (int i=0; i<shots.length; i++) {
System.out.print(shots[i]);
if (i < shots.length-1) {
System.out.print(", ");
}
else {
System.out.println("");
}
}
}
}
As commentors said, please provide error messages.
However, I can pick out several issues just for starters. Let's look at your main method...
public static void main(String[] args) {
System.out.print("Enter Player's Free Throw Percentage: ");
Scanner input = new Scanner(System.in);
int percent = input.nextInt();
print int [](shots);
}
In this call to the print method, why do you have int [] in there? Are you trying to cast something to an int array? Anyways, that has to come out.
Also, you are passing the print method some shots variable that doesn't exist.
Your print method takes an int array as its only argument, so you have to pass it a valid int array. Perhaps you meant to call getRandomNumbers() and pass the int array that it returns to the print method?
Also, what's with the nested classes you're showing. You have this class Final with another class ShotClass defined inside of it. And your closing brackets are all out of whack.
In short, you need to do as the comments ask and format your code and then work through each individual error message, because you've got a whole lot to fix.
EDIT
I'm not sure if I'm doing you more harm than good by giving you the answer to your homework assignment, but I feel for you so here it is. Please just look very carefully at the exact differences between what you posted in your question and what I show below. There's several mistakes you made, including bad syntax and a misunderstanding of how scope works, and I can't properly explain all the problems without typing several pages, so I hope you can learn from this example instead...
import java.util.*;
public class Final {
public static void main(String[] args) {
System.out.print("Enter Player's Free Throw Percentage: ");
Scanner input = new Scanner(System.in);
int percent = input.nextInt();
int[] shots = getRandomNumbers();
print(shots);
}
public static int[] getRandomNumbers(){
int [] shots = new int [10];
Random r = new Random();
for(int i = 0; i < 10; i++) {
shots[i] = r.nextInt(100);
}
return shots;
}
public static void print(int[] shots) {
for (int i=0; i<shots.length; i++) {
System.out.print(shots[i]);
if (i < shots.length-1) {
System.out.print(", ");
}
else {
System.out.println("");
}
}
}
}//END class
Write a class called Average that can be used to calculate average of several integers. It should contain the following methods:
A method that accepts two integer parameters and returns their average.
A method that accepts three integer parameters and returns their average.
A method that accepts two integer parameters that represent a range. Issue an error message and return zero if the second parameter is less than the first one. Otherwise, the method should return the average of the integers in that range (inclusive).
I am totally new to Java and programming, this has me completely lost! Here's what I've tried.
import java.util.Scanner;
public class Average {
public static void main(String[] args) {
double numb1, numb2, numb3;
System.out.println("Enter two numbers you'd like to be averaged.");
Scanner keyboard = new Scanner(System.in);
numb1 = keyboard.nextInt();
numb2 = keyboard.nextInt();
}
public double average (int num1, int num2) {
return (num1 + num2) / 2.0;
}
public double average (int num1, int num2, int num3)
{
return (num1 + num2 + num3) / 3.0;
}
}
The program doesn't go past getting the values from the user. Please help!
You have to actually call your methods.
Just place
Average avg = new Average();
System.out.println("The average is: " + avg.average(numb1, numb2));
at the end of your main method.
Alternatively you can make the methods static:
public static double average (int num1, int num2) {
return (num1 + num2) / 2.0;
}
More info on constructors and static.
It looks like your not actually printing out the results. Try the following.
System.out.print(average(numb1, numb2));
Let's detail what you did there.
public static void main(String[] args) {
//Create variables numb1, numb2 & numb3
double numb1, numb2, numb3;
System.out.println("Enter two numbers you'd like to be averaged.");
//Read standard input (keyboard)
Scanner keyboard = new Scanner(System.in);
//Retrieve first input as an int
numb1 = keyboard.nextInt();
//Retrieve second input as an int
numb2 = keyboard.nextInt();
}
Then your two next methods compute for two or three given integers their average.
The main method is the first method called during your program execution. The jvm will execute everything inside. So it will declare the three doubles, read two values from keyboard and then end.
If you want to compute the average of numb1 & numb2 using your method, you have to create an object Average and call your average method like this
public static void main(String[] args) {
//Create variables numb1, numb2 & numb3
double numb1, numb2, numb3;
System.out.println("Enter two numbers you'd like to be averaged.");
//Read standard input (keyboard)
Scanner keyboard = new Scanner(System.in);
//Retrieve first input as an int
numb1 = keyboard.nextInt();
//Retrieve second input as an int
numb2 = keyboard.nextInt();
//Declare the average value
double average;
//Create an average instance of the class average
Average averageObject = new Average();
//Call your average method
average = averageObject.average(numb1,numb2);
//Print the result
System.out.println("Average is : " + average);
}
Everything in Java is object (read about Object Oriented Programming).
Writing your class "Average" defines how your object is structured. It has attributes (characteristics) and methods (actions). Your Average object has no attributes. However it has two methods (average with two and three numbers) acting on integers.
However your class is just the skeleton of your object. You need to create an object from this skeleton using the keyword new as :
Average averageObject = new Average();
Sincerely
public class Marks {
int roll_no;
int subject1;
int subject2;
int subject3;
public int getRoll_no() {
return roll_no;
}
public void setRoll_no(int roll_no) {
this.roll_no = roll_no;
}
public int getSubject1() {
return subject1;
}
public void setSubject1(int subject1) {
this.subject1 = subject1;
}
public int getSubject2() {
return subject2;
}
public void setSubject2(int subject2) {
this.subject2 = subject2;
}
public int getSubject3() {
return subject3;
}
public void setSubject3(int subject3) {
this.subject3 = subject3;
}
public void getDetails(){
Scanner sc = new Scanner(System.in);
System.out.println("Enter the marks of subject1");
this.subject1 = sc.nextInt();
System.out.println("Enter the marks of subject2");
this.subject2 = sc.nextInt();
System.out.println("Enter the marks of subject3");
this.subject3 = sc.nextInt();
System.out.println("Enter the roll number");
this.roll_no = sc.nextInt();
}
public int getAverage(){
int avg = (getSubject1() + getSubject2() + getSubject3()) / 3;
return avg;
}
public void printAverage(){
System.out.println("The average is : " + getAverage());
}
public void printRollNum(){
System.out.println("The roll number of the student is: " + getRoll_no());
}
public static void main(String[] args){
Marks[] e1 = new Marks[8];
for(int i=0; i<2; i++) {
System.out.println("Enter the data of student with id:");
e1[i] = new Marks();
e1[i].getDetails();
e1[i].printAverage();
}
System.out.println("Roll number details");
for(int i=0; i<2; i++){
e1[i].printRollNum();
}
}
}
If you'd like your program to find the average you need to include a call to that method in your main method.
numb1 = keyboard.nextInt();
numb2 = keyboard.nextInt();
System.out.println("The average of " + numb1 + " and " + numb2 + " is " + average(numb1,numb2);
}
you need to call the methods that you have written after you accept the input.
...
System.out.println("Enter two numbers you'd like to be averaged.");
Scanner keyboard = new Scanner(System.in);
numb1 = keyboard.nextInt();
numb2 = keyboard.nextInt();
System.out.println(average (int numb1 , int numb2 ))
...
You probably want to provide a menu of options for the user to select to determine which method to call
System.out.println("Select one option");
System.out.println("1. Enter two numbers you'd like to be averaged.");
System.out.println("2. Enter the 3 numbers you want averaged.");
System.out.println("3. Enter the number Range you want averaged.");
and based on that answer you can determine which method to call
After the access specifier (public) and before the return type (double) place the Java keyword static. You shouldn't worry about what this means right now.
You have to use bitwise operators.
average of int a and b can be calculated as
avg= (a >> 1) + (b >> 1) + (((a & 1) + (b & 1)) >> 1);
The main method will only execute what it is asked to. If you want the average methods to be executed, you will have to create an object, pass the required variable and call the methods from the main method. Write the following lines in the main method after accepting the input.
Average avrg = new Average();
System.out.println("The average is: " + avrg.average(numb1, numb2, numb3));
Write only numb1 and numb2 if you want to average only two numbers.
I have been asked to create a simple input output code for a training exercise in a new job using Java. I am a complete novice with Java so therefore I have hit a bit of a wall. This is my current code...
import java.util.*;
public class Task3
{
static Scanner console = new Scanner(System.in);
public static void main(String[] args)
{
{
int Number1;
int Number2;
int Number3;
int Sum;
Number1= console.nextInt();
Number2= console.nextInt();
Number3= console.nextInt();
Volume = Number1 * Number2 + Number3 ;
}
System.out.printIn("Answer:" + Sum ) ;
}
}
Effectively I want this code to read 3 numbers as input from the user and then produce the sum of Number1 x Number2 + Number3 as output. I'm sure there are a few ways to do this but the way I have started above is the way we have been asked to do it. Any help would be much appreciated as I am keen to learn more about this and where I am having trouble... Thanks in advance, John
Check this:
import java.util.*;
public class MyJavaProgram
{
static Scanner console = new Scanner(System.in);
public static void main(String[] args) {
int number1 = console.nextInt();
int number2 = console.nextInt();
int number3 = console.nextInt();
System.out.println("Volume = "+ ((number1 * number2) + number3));
}
}
Changes from your code:
Removed a set of brackets which were creating a local scope where Sum was defined, yet you were trying to use Sum outside of that local scope
Variable defined as Sum but then referred to as Volume; I assume this was a copy & paste error.
Just for adding three numbers. Program should be
public static void main(String[] args) throws IOException {
Scanner s = new Scanner(System.in);
int num1= s.nextInt();
int num2= s.nextInt();
int num3= s.nextInt();
System.out.println("Sum= "+ (num1+ num2+num3));
// or play any game with those variables here
}
You are adding extra {} and variables without any use.Get rid off those.