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A Java program with a loop that allows the user to enter a series of integers, then displays the smallest and largest numbers + the average

I've got an assignment that requires me to use a loop in a program that asks the user to enter a series of integers, then displays the smallest and largest numbers AND gives an average. I'm able to write the code that allows the user to enter however many integers they like, then displays the smallest and largest number entered. What stumps me is calculating the average based on their input. Can anyone help? I'm sorry if my code is a little janky. This is my first CS course and I'm by no means an expert.
import javax.swing.JOptionPane;
import java.io.*;
public class LargestSmallest
{
public static void main(String[] args)
{
int number, largestNumber, smallestNumber, amountOfNumbers;
double sum, average;
String inputString;
inputString = JOptionPane.showInputDialog("Enter an integer, or enter -99 to stop.");
number = Integer.parseInt(inputString);
largestNumber = number;
smallestNumber = number;
sum = 0;
for (amountOfNumbers = 1; number != -99; amountOfNumbers++)
{
inputString = JOptionPane.showInputDialog("Enter an integer, or enter -99 to stop.");
number = Integer.parseInt(inputString);
if (number == -99)
break;
if (number > largestNumber)
largestNumber = number;
if (number < smallestNumber)
smallestNumber = number;
sum += number;
}
average = sum / amountOfNumbers;
JOptionPane.showMessageDialog(null, "The smallest number is: " + smallestNumber + ".");
JOptionPane.showMessageDialog(null, "The largest number is: " + largestNumber + ".");
JOptionPane.showMessageDialog(null, "The average off all numbers is: " + average + ".");
}
}

The problem is that you do an extra
inputString = JOptionPane.showInputDialog("Enter an integer, or enter -99 to stop.");
number = Integer.parseInt(inputString);
at the beginning. You don't count that in a sum. That's why you get unexpected results.
The fix would be:
replace the declarations line with:
int number = 0, largestNumber, smallestNumber, amountOfNumbers;
Remove
inputString = JOptionPane.showInputDialog("Enter an integer, or enter -99 to stop.");
number = Integer.parseInt(inputString);
That go before the loop
Replace for (amountOfNumbers = 0 with for (amountOfNumbers = 1

This is my first CS course
Then allow me to show you a different way to do your assignment.
Don't use JOptionPane to get input from the user. Use a Scanner instead.
Rather than use a for loop, use a do-while loop.
Usually you declare variables when you need to use them so no need to declare all the variables at the start of the method. However, be aware of variable scope.
(Notes after the code.)
import java.util.Scanner;
public class LargestSmallest {
public static void main(String[] args) {
Scanner stdin = new Scanner(System.in);
int largestNumber = Integer.MIN_VALUE;
int smallestNumber = Integer.MAX_VALUE;
int number;
double sum = 0;
int amountOfNumbers = 0;
do {
System.out.print("Enter an integer, or enter -99 to stop: ");
number = stdin.nextInt();
if (number == -99) {
break;
}
if (number > largestNumber) {
largestNumber = number;
}
if (number < smallestNumber) {
smallestNumber = number;
}
sum += number;
amountOfNumbers++;
} while (number != -99);
if (amountOfNumbers > 0) {
double average = sum / amountOfNumbers;
System.out.printf("The smallest number is: %d.%n", smallestNumber);
System.out.printf("The largest number is: %d.%n", largestNumber);
System.out.printf("The average of all numbers is: %.4f.%n", average);
}
}
}
largestNumber is initialized to the smallest possible number so that it will be assigned the first entered number which must be larger than largestNumber.
Similarly, smallestNumber is initialized to the largest possible number.
If the first value entered is -99 then amountOfNumbers is zero and dividing by zero throws ArithmeticException (but maybe you haven't learned about exceptions yet). Hence, after the do-while loop, there is a check to see whether at least one number (that isn't -99) was entered.
You don't need to use printf to display the results. I'm just showing you that option.

Which part of my program is in the wrong loop? JAVA

The project is to create a program that takes input from the user in JOption Pane and checks if a number is prime or not. The program is supposed to loop until the user enters 0, which triggers the program to calculate max, min, sum, count, and average.
Ive completed 99% of the assignment, except the first number that I enter does not get printed out like the others but it still gets included in calculations
import javax.swing.*;
import java.util.*;
public class Assignment4 {
public static void main(String[] args) {
// Main Method
userInput();
}
public static void userInput() {
int number;
int sum;
int count; // declaring variables
int max= 0;
int min= 1;
float average;
String userNumber; // Number typed by user
sum = 0; // start at 0 for sum
count = 0; // start at 0 for counter
// prompt user to enter a positive number
userNumber = JOptionPane.showInputDialog("Enter a positive integer or 0 to quit");
// convert to int
number = Integer.parseInt(userNumber);
// if the number entered is positive and not 0, the loop repeats
while ( number != 0 && number > 0) {
sum += number;
// starting count and sum at 0
count++;
// repeating user input prompt unless 0 is entered
// storing values for min and max as we go
if (number > max)max=number;
if (number < min & number != 0)min=number;
userNumber = JOptionPane.showInputDialog("Enter a positive integer or 0 to quit");
number = Integer.parseInt( userNumber );
// checking if number entered is prime or not
int i,m=0,flag=0;
m=number/2;
if(number==0||number==1){
System.out.println(number+" is not a prime number");
}else{
for(i=2;i<=m;i++){
if(number%i==0){
System.out.println(number+" is not a prime number");
flag=1;
break;
}
}
if(flag==0){ System.out.println(number+" is a prime number"); }
}
}
if ( count != 0 ) {
// as long as one number is entered, calculations are done below
// calculate average of all numbers entered
average = (float) sum / count;
// printing out the results
System.out.printf("The average is : %.3f\n", average);
System.out.println("The sum is : "+sum);
System.out.println("The count is : "+count);
System.out.println("The max is : "+max);
System.out.println("The min is : "+min);
}
}
}
i need the first entry to print like the rest, please help me find where to put in the loop

Can you explain more what you need? What input do you give it and what output do you see?
I noticed that you're adding numbers before the call to JOptionPane, is it possible that you have count larger by one than your actual count of numbers? Your indentation is terrible, you should clean it up, I'm having trouble reading the code period.
// 1 START OF LOOP
while ( number != 0 && number > 0) {
// 2 ADD NUMBER TO SUM
sum += number;
// starting count and sum at 0
count++;
// repeating user input prompt unless 0 is entered
// storing values for min and max as we go
if (number > max)max=number;
if (number < min & number != 0)min=number;
// 3 THEN GET INPUT. WHAT???
userNumber = JOptionPane.showInputDialog("Enter a positive integer or 0 to quit");

You have several issues in your program. The reason why the first number is never considered is that you have
userNumber = JOptionPane.showInputDialog("Enter a positive integer or 0 to quit");
number = Integer.parseInt( userNumber );
two times in your code (before the while loop and in the while loop).
I would suggest to initialize number with Integer.MAX_VALUE: number = Integer.MAX_VALUE;
Then remove
userNumber = JOptionPane.showInputDialog("Enter a positive integer or 0 to quit");
number = Integer.parseInt( userNumber );
before the while loop.
There is a & missing in if (number < min & number != 0)min=number;
=>
if (number < min && number != 0) {
min=number;
}
The condition in the while loop can be simplified by writing while ( number > 0) { because > 0 means != 0 too.
I would also suggest to write your code a little better for readability. Always use curly braces for conditions (if), even when you only execute one line if the condition is true.
I hope this helps. Let me know if you need more help but you should be able to solve this assignment now on your own :)

how to get the sum, average, minimum and maximum of five numbers-java using do-while loop

I'm trying to get the sum, average, minimum and maximum of five numbers but somehow I get this output. I'm trying to re-code it all over again but it is still the same. Can you help me check this guys...
Here's my code:
import java.util.*;
public class Kleine {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
double average;
int count = 0, sum = 0, num, min = 0, max = 0;
System.out.println("Please enter the number of numbers you wish to evaluate:");
do {
num = scan.nextInt();
sum += num;
count++;
} while (count < 5);
average = sum / 5;
{
if (num > max) {
max = num;
}
if (num < min) {
min = num;
}
}
System.out.println("Your average is: " + average);
System.out.println("The sum is: " + sum);
System.out.println("Your maximum number is: " + max);
System.out.println("Your minimum number is: " + min);
}
}
Here's the output:
Please enter the number of numbers you wish to evaluate:
1
10
5
-3
6
Your average is3.0
The sum is:19
Your maximum number is 6
Your minimum number is 0
BUILD SUCCESSFUL (total time: 19 seconds)
The minimum and maximum numbers goes somewhere...
a little advice please...

The best way to handle the min/max values is to keep track of them as your read in each value:
int sum = 0;
int max = Integer.MIN_VALUE;
int min = Integer.MAX_VALUE;
for (int i=0; i < 5; ++i) {
num = scan.nextInt();
if (num > max) max = num;
if (num < min) min = num;
sum += num;
}
double average = sum / 5.0d;
I seed the max and min values with the smallest/largest integer values, respectively. This lets us capture the actual min and max values as they are read in. Also, I think that a basic for loop works better here than a do while loop.
Note that I compute the average using a double type, because it may not be a pure integer value (even in your sample data the average is not an integer).

Use
int max = Integer.MIN_VALUE;
int min = Integer.MAX_VALUE;
And your
{
if(num>max)
max=num;
if(num<min)
min=num;
}
needs to be inside the do-while loop, or else it runs only for the last value of number entered.

For a start you can use Math.min & Math.max. The average is sum / count.
An example getting a min number without a loop would be:
long min = Integer.MAX_VALUE;
min = Math.min(min, 9);
min = Math.min(min, 4);
min = Math.min(min, 6);
// min = 4
Do something similar for max.
You'd also be better off starting with a list or array of numbers. Get the output right, then add more complicated things like user input.

You can do it this way without defining number of integers to read:
import java.util.ArrayList;
import java.util.IntSummaryStatistics;
import java.util.List;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
List<Integer> numbers = new ArrayList<>();
Scanner in = new Scanner(System.in);
while (true) {
System.out.println("Next number?");
numbers.add(in.nextInt());
IntSummaryStatistics summaryStatistics = numbers.stream()
.mapToInt(Integer::valueOf)
.summaryStatistics();
System.out.println(String.format("Max: %d, Min: %d, Average: %s, Sum: %d", summaryStatistics.getMax(), summaryStatistics.getMin(), summaryStatistics.getAverage(), summaryStatistics.getSum()));
}
}
}

If I just change the existing code, the logic should be like below:
do{
num=scan.nextInt();
sum+=num;
if(count==0){
min=num;
max=num;}
if(num>max)
max=num;
if(num<min)
min=num;
count++;
}while(count<5);
average = sum/5;
The issue was that your min-max condition was outside the loop and you were initializing min and max by 0. You should set min/max to your first input number.

Min and Max were now equal to the max and min of integer. now if any number is less than min and greater than max, min and max takes their position. The average and the sum functionality was great. The problem in your code was that it was getting the max and min after the loop for input has executed. The flow was wrong.
import java.util.*;
public class Kleine {
public static void main(String[] args) {
Scanner scan=new Scanner(System.in);
double average;
int count=0, sum=0, num=0;
int max = Integer.MIN_VALUE;
int min = Integer.MAX_VALUE;
System.out.println("Please enter the number of numbers you wish to evaluate:");
do{
if(num>max) max=num;
if(num<min) min=num;
num=scan.nextInt();
sum+=num;
count++;
}while(count<5);
average = sum/5;
System.out.println("Your average is"+average);
System.out.println("The sum is:"+sum);
System.out.printf("Your maximum number is %d\n",max);
System.out.printf("Your minimum number is %d\n",min);
}
}

calculate minimum value from user input while excluding loop termination number (-1)

Hey I'm trying to work out the minimum and maximum value from user input while disregarding the loop terminated value, which is -1. I understand how to do everything except how to disregard -1 when calculating minimum value for the input.
Here's the code I've got so far:
int value = 0;
int max = value;
int min = max;
Scanner scan = new Scanner(System.in);
while (value != -1) {
System.out.print("Value: ");
value = scan.nextInt();
if (min > value) {
min = value; }
if (max < value) {
max = value; }
}
System.out.println("Min = " + min);
System.out.println("Min = " + min);
How can I calculate the minimum value while disregarding -1?
Thanks.

You turn the loop into a never-ending loop, and add a break when termination number is detected:
Scanner scan = new Scanner(System.in);
int max = Integer.MIN_VALUE;
int min = Integer.MAX_VALUE;
for (;;) { // never-ending loop
System.out.print("Value: ");
if (! scan.hasNextInt()) {
System.out.println("** Invalid input **");
scan.nextLine(); // discard invalid input
continue; // loop back to prompt again
}
int value = scan.nextInt();
if (value == -1) // termination number
break;
if (value < min)
min = value;
else if (value > max)
max = value;
}
System.out.println("Min = " + min);
System.out.println("Max = " + max);
Also fixed:
Initialization of min and max (otherwise min will likely always be 0)
Validation of Scanner input (so program doesn't die with exception on bad input)
Printing of max (was printing min twice)
Indentation (so code structure is clearly visible to human readers)

Add if (value == -1) break; right before the line that starts withif (min > value). This causes the loop to break once the terminal (-1) character is read.
For clarity, you can then change your loop condition to while(true). This is a pretty common idiom for this situation.

Java error in calculation when comparing largest and smallest numbers & sum with while loop

Here is my assignment:
Write a program to read a list of nonnegative integers and to display the largest integer, the smallest integer, and the average of all the integers. The user
indicates the end of the input by entering a negative sentinel value that is not
used in finding the largest, smallest, and average values. The average should
be a value of type double so it will be computed with a fractional part.
I've gotten different parts to work with different methods: Method A makes the maximum and minimum correct and the sum wrong and Method B makes the sum and maximum correct and the minimum wrong. The following code demonstrates Method B. Some variables are commented out:
public class testthis2
{
public static void main(String[] args) {
System.out.println("Enter Numbers of Nonnegative Integers.");
System.out.println("When complete, enter -1 to end input values.");
Scanner keyboard = new Scanner(System.in);
//int max = keyboard.nextInt();
int max = 0;
int min = max; //The max and min so far are the first score.
//int next = keyboard.nextInt();
int count = 0;
int sum = 0;
boolean areMore = true;
boolean run_it = false; //run it if its true
//if (max <= -1) {
// System.out.println("Thanks for playing!");
// run_it = false;
//}
// else
// run_it = true;
while(areMore) //always true
{
int next = keyboard.nextInt();
//int max = 0;
// min = max;
if (next < 0) { //if -1 is entered end loop.
areMore = false;
run_it = false;
break;
}
else //run this badboy
if(next >= max)
max = next;
else if(next <= min)
min = next;
run_it = true;
sum += next;
count++;
}
if (run_it = true)
System.out.println("The highest score is " + max);
System.out.println("The lowest score is " + min);
System.out.println("count " + count);
System.out.println("sum " + sum);
System.out.println("average " + (double)(sum/count));
System.out.println("Thanks for playing!");
}
}
When I run this test, the maximum, sum, count, and average are all correct. However, the minimum is wrong, because 0 was clearly not entered. Here's an example test-run:
When complete, enter -1 to end input values.
37
25
30
20
11
14
-1
The highest score is 37
The lowest score is 0
count 6
sum 137
average 22.0
Thanks for playing!
Any help would be greatly appreciated. Thanks!

The smallest iteger is always 0 because there is no nonnegative integer that is less then 0 :)
if(next <= min) // for nonnegative integer this expression will return true only for 0
min = next;
So try to initialize the "min" variable as Integer.MAX_VALUE. I believe it will help you.

There are 2 problems with the code:
You initialize min to 0 so it never gets updated because it will always be <= any valid number you enter. Try initializing it to Integer.MAX_VALUE. conversely also initialize max to Integer.MIN_VALUE
You are not correctly computing the average value: (double)(sum/count) will first do integer division which truncates the value THEN gets cast to double do this instead ((double)(sum )/count) or optionally make the type of sum a double.

Looks like you initialize min and max both to 0.
Then the only code that will ever change min or max is based on user input. If the input value (next) is >= max, max will change to that value. This should happen on the first input.
The problem is you try setting min the same way. if (next <= min), but min was initialized to 0, so next can only be <= min if next is less than 0.
You need to initialize max and min on the user's first input. They should both start equal to the user's first input before you compare future inputs to their value.