Develop Reference

java.util.NoSuchElementException reading user input

I'm getting an error message (java.util.NoSuchElementException) in thread main when attempting to compile the following code with the input 3, then 4, 5, and 7. I've tried to tweak the code, but there's something I'm missing. I was thinking it may be due to my use of arrays since I am just learning how to use those, but I've tried to look closely at them and I didn't see anything I did wrong, but I definitely missed something. Any help would be appreciated. Thanks!
import java.util.Scanner;
public class ArrayMethods2 {
public static int[] findMinAndMax(int[] x) {
int i;
int min = x[0];
int max = x[0];
for (i = 0; i < x.length; i++) {
if (x[i] < min) {
min = x[i];
}
if (x[i] > max) {
max = x[i];
}
}
int [] minAndMax = new int[2];
minAndMax[0] = min;
minAndMax [1] = max;
return minAndMax;
}
public static double averageWithDrop(int[] x) {
int i;
int min = x[0];
int minIndex1 = 0;
int minIndex2 = 0;
int sum = 0;
for (i = 0; i < x.length; i++) {
if (x[i] < min) {
minIndex1 = i;
}
}
for (i = 0; i < x.length; i++) {
if (x[i] < min) {
if (i != minIndex1)
minIndex2 = i;
}
}
for (i = 0; i < x.length; i++) {
if (i == minIndex1) {
sum = sum + 0;
}
else if (i == minIndex2) {
sum = sum + 0;
}
else {
sum = sum + x[i];
}
}
double average = sum / (x.length - 2);
return average;
}
public static void main (String[] args) {
Scanner scnr = new Scanner(System.in);
System.out.print("How many numbers would you like to enter? (must be at least 3) ");
int userValue = scnr.nextInt();
System.out.println(userValue);
while (userValue < 3) {
System.out.println("Invalid value, must be at least 3. Please try again ");
userValue = scnr.nextInt();
System.out.println(userValue);
}
int x = 0;
int indexVal;
int [] userArray = new int [userValue];
while (x <= userValue) {
System.out.print("Enter value for index " + x + ": ");
indexVal = scnr.nextInt();
System.out.println(indexVal);
userArray[x] = indexVal;
x++;
}
int [] minAndMaxVal = new int [2];
minAndMaxVal = findMinAndMax(userArray);
System.out.println("Min value: " + minAndMaxVal[1] + ", Max value: " + minAndMaxVal[2]);
double avg = averageWithDrop(userArray);
System.out.println("Average excluding two lowest values: " + avg);
}
}

Running your code, I did not get any NoSuchElementException, however I got IndexOutOfBoundsException. Check the class your are running.
Please remember arrays are 0 based.
In the main method change while (x <= userValue)to while (x < userValue)
Again, arrays are 0 based, change:
System.out.println("Min value: " + minAndMaxVal[1] + ", Max value: " + minAndMaxVal[2]);
to
System.out.println("Min value: " + minAndMaxVal[0] + ", Max value: " + minAndMaxVal[1]);

There are few problems in the code :
Update this (x <= userValue) to (x<userValue) , else it will give array index out of bounds exception
Start the for loop in minMaxFunction from 1 , since you have already stored the value of arr[0] to min and max like below . This is just an optimization in the code.
for (i = 1; i < x.length; i++) {
if (x[i] < min) {
min = x[i];
}
if (x[i] > max) {
max = x[i];
}
}
This line in main method should have index 0 and index 1 . There is no index 2 since you have declared the array of length 2 , else it will give array index out of bounds exception
minAndMaxVal = findMinAndMax(userArray);
System.out.println("Min value: " + minAndMaxVal[0] + ", Max value: " + minAndMaxVal[1]);

Is there perhaps a way of finding the above and below average

I'm creating a program to find the average of all the numbers entered by the user and storing those numbers to check whether the number entered falls below or above the average that was calculated.
My program outputs all numbers entered as below average. i have check on stack overflow for similar problems i have tried all that but my output still displays below the average only
This is what i have tried
public void newspaper()
{
System.out.println("Question 4 \n");
int youth;
double avg =0;
int sum = 0;
int numYouth = 5;
//The loop for calculating the average
for (int i = 1; i <= 5; i++)
{
System.out.println("Youth " + i + " How many was delivered?");
youth = in.nextInt();
sum = sum + youth;
avg = sum / numYouth;
}
System.out.println("Average is: " + avg+ "\n");
double aboveAvg = 0;
//The loop for checking below of above average
for (int j = 1; j <=5; j++)
{
if(aboveAvg > avg)
{
System.out.println("Youth " + j + " is above average");
aboveAvg++;
}
else
{
System.out.println("Youth " + j + " below average");
}
}
}

This is a possible solution for your problem:
Note that you need to store the user inputs, calculate the average once (not inside the for loop), and finally compare the numbers stored with the average calculated before.
public void newspaper() {
Scanner in = new Scanner(System.in);
System.out.println("Question 4 \n");
double avg = 0;
int sum = 0;
int[] youths = new int[5];
// The loop for calculating the average
for (int i = 0; i < youths.length; i++) {
System.out.println("Youth " + (i + 1) + " How many was delivered?");
youths[i] = in.nextInt();
sum = sum + youths[i];
}
// Note that the average can be calculated once, not every iteration
avg = sum / youths.length;
System.out.println("Average is: " + avg + "\n");
// The loop for checking below of above average
for (int i = 0; i < youths.length; i++) {
if (youths[i] > avg) {
System.out.println("Youth " + (i + 1) + " is above average");
} else {
System.out.println("Youth " + (i + 1) + " below average");
}
}
}

Try to use array instead of variable
see below code
import java.util.Scanner;
public class Stackoverflow {
public void newspaper() {
System.out.println("Question 4 \n");
double avg = 0;
int sum = 0;
int numYouth = 5;
int youth[] = new int[numYouth];
Scanner sc = new Scanner(System.in);
// The loop for calculating the average
for (int i = 0; i < 5; i++) {
System.out.println("Youth " + i + " How many was delivered?");
youth[i] = sc.nextInt();
sum = sum + youth[i];
avg = sum / numYouth;
}
System.out.println("Average is: " + avg + "\n");
double aboveAvg = 0;
// The loop for checking below of above average
for (int j = 0; j < 5; j++) {
if (youth[j] > avg) {
System.out.println("Youth " + j + " is above average");
} else {
System.out.println("Youth " + j + " below average");
}
}
}
public static void main(String[] args) {
new Stackoverflow().newspaper();
}
}

You need to store the numbers in a temporary list and use counter 'ctr' for incrementing the values of the matched case. I have used for each loop for simplicity.
public void newspaper() {
System.out.println("Question 4 \n");
int youth;
double avg = 0;
int sum = 0;
int numYouth = 5;
List<Integer> number = new ArrayList<>();
// The loop for calculating the average
int ctr = 0;
for (int i = 0; i < 5; i++) {
System.out.println("Youth " + ++ctr + " How many was delivered?");
youth = in.nextInt();
number.add(youth);
sum = sum + youth;
avg = sum / numYouth;
}
System.out.println("Average is: " + avg + "\n");
ctr = 0;
// The loop for checking below of above average
for (int j : number) {
if (j > avg) {
System.out.println("Youth " + ++ctr + " is above average");
} else {
System.out.println("Youth " + ++ctr + " below average");
}
}
}

Assuming that you're trying to 'find the average of all the numbers entered by the user, storing those numbers to check whether each of the numbers entered falls below or above the average that was calculated', below are the things you need to fix:
The "storing those numbers" part
Compare the calculated average against the stored number.
A possible solution:
Use a list or an array to store the numbers entered by the user.
You can use an array as long as you know the number of elements to store before starting to read the numbers.
Read values from the list/array when you want to compare the entered value with the calculated average.
public void newspaper()
{
System.out.println("Question 4 \n");
int youth;
double avg =0;
int sum = 0;
int numYouth = 5;
// Create a list to store the entered values
// List<Integer> enteredNumbers = new ArrayList<Integer>();
// Using an array of '5' elements - this 5 comes from numYouth
int[] enteredNumbers = new int[numYouth]; // better not to 'hardcode'
//The loop for calculating the average
for (int i = 1; i <= numYouth; i++)
{
System.out.println("Youth " + i + " How many was delivered?");
youth = in.nextInt();
enteredNumbers[i-1] = youth; // array is 0-indexed
sum = sum + youth;
avg = sum / numYouth;
}
System.out.println("Average is: " + avg+ "\n");
// an int is enough to track the number of values above the average
int aboveAvg = 0;
//The loop for checking below of above average
for (int j = 1; j <= numYouth; j++)
{
// compare stored value against the average calculated above
if(enteredNumbers[j-1] > avg) // array is 0-indexed
{
System.out.println("Youth " + j + " is above average");
aboveAvg++;
}
else
{
System.out.println("Youth " + j + " below average");
}
}
System.out.println(aboveAvg + " Youths are above average");
}

This program should ask user for the max num to print out to and then calculate each number starting from 1 to the maximum along with it squared

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.print("Please enter the max number:");
int max = input.nextInt();
int[]arr1 = new int[max+1];
int[]arr2 = new int[max+1];
int[]arr3 = new int[max+1];
int i = 1;
// For-loop to calculate
for (i = 1;i <= max;i++)
arr1[i] = arr1[i-1] + i;
i = 1;
// While-loop to calculate
while (i <= max) {
arr2[i] = arr2[i-1] + i;
i++;
}
i = 1;
// Do-While-loop to calculate
do
arr3[i] = arr3[i-1] + i;
while (++i <= max);
for (i = 0; i <= max; i++)
System.out.println("Arr1 " + arr1[i] + " Arr2 " + arr2[i] + " Arr3 " + arr3[i]);
System.out.println("Sum of All is " + arr1[max]);
}
I have this for doing sums but I am stuck when it comes to getting it to square

You seem to have 3 identical array objects?
Anyway, it's pretty straightforward to print the square of all numbers from 1 to max:
for (int i = 1; i <= max; i++) {
System.out.println(i + ": " + i * i);
}
There are also some fun ways to sum up the numbers from 1 to max, such as:
System.out.println(IntStream.range(1, max + 1).sum());

The variable sum in the while loop is concating and not adding

Here's my code:
public static int baseB2int(String number, int base)
{
int product = 0;
int num = Integer.parseInt(number);
int sum;
int i = number.length();
int[] theNumber = new int[i];
for (int j = 0; j < number.length(); j++)
{
System.out.println("the length of number is " + number.length());
theNumber[j] = num%base;
System.out.println("theNumber["+j+"] is " + theNumber[j]);
num = num/base;
System.out.println("the num is "+num);
}
sum = theNumber[i - 1];
System.out.println("the sum is " + sum);
while (i > 0)
{
product = sum * base;
System.out.println("The product in the while loop is " + product);
System.out.println("theNumber[previous]" + theNumber[i-1]);
sum = product + theNumber[i-1];
System.out.println("the sum in the while loop is " + sum);
i--;
}
return product;
}

string multiplication using a big integer class

I'm trying to write a code that multiplies two strings of integers. I'm not too sure where it's going wrong... It works for some numbers, but is horribly wrong for others. I'm not asking for a full solution, but just a hint (I seriously appreciate any help possible) as to where I'm making the obviously silly mistake. Thanks in advance.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.print("Please enter a big integer. ");
String t = scan.nextLine();
System.out.print("And another. ");
String s = scan.nextLine();
BigInt a = new BigInt(t);
BigInt b = new BigInt(s);
System.out.println(a + " + " + b + " = " + a.add(b));
System.out.println(a + " - " + b + " = " + a.sub(b));
System.out.println(a + " * " + b + " = " + a.mul(b));
System.out.println(a + " / " + b + " = " + a.div(b));
}
}
class BigInt {
public BigInt() {
n = new int[1];
}
public BigInt(String s) {
n = new int[s.length()];
for (int i = 0; i < n.length; ++i) {
n[n.length - i - 1] = s.charAt(i) - '0' ;
}
}
private BigInt(int[] n) {
this.n = new int[n.length];
for (int i = 0; i < n.length; ++i) {
this.n[i] = n[i];
}
}
public String toString() {
String s = "";
for (int i : n) {
s = i + s;
}
return s;
}
public BigInt mul(BigInt o) {
int carry = 0;
int s = 0;
int digit;
int subtotal = 0;
int total = 0;
int max = n.length > o.n.length ? n.length : o.n.length;
int[] result = new int[n.length + o.n.length];
for (int i = 0; i < o.n.length; ++i) {
int bottom = i <= o.n.length ? o.n[i] : 0;
for (s = 0; s <= n.length; ++s){
int top = s < n.length ? n[s] : 0;
int prod = (top * bottom + carry);
if (s == (max-1)) {
total = Integer.valueOf((String.valueOf(prod) + String.valueOf(subtotal)));
carry = 0;
digit = 0;
subtotal = 0;
break;
}
if (prod < 10) {
digit = prod;
subtotal += digit;
carry = 0;
}
if (prod >= 10); {
digit = prod % 10;
carry = prod / 10;
subtotal += digit;
}
}
result[i] = total;
}
return new BigInt(trim(result));
}
private int[] trim(int[] nums) {
int size = nums.length;
for (int i = nums.length - 1; i > 0; --i) {
if (nums[i] != 0) {
break;
}
--size;
}
int[] res = new int[size];
for (int i = 0; i < size; ++i) {
res[i] = nums[i];
}
return res;
}
private int[] n;
}

A quick test using:
for (int x = 0; x < 10; x++) {
for (int y = 0; y < 10; y++) {
System.out.println(x + " * " + y + " = " + new BigInt(Integer.toString(x)).mul(new BigInt(Integer.toString(y))));
}
}
demonstrates that somehow your multiply of x * y is actually multiplying by 10x * y. That should give you a clear hint to the problem.