My school homework is to declare array with 100 variables.
The actual task is: Declare array with 100 variables. Use do.. while loop to read the data to array. Reading data should be finished when array will be full or when user will enter a negative number.
So far I got:
public static void runTask1() {
Scanner read = new Scanner(System.in);
int[] tab = new int [100];
for (int i = 0; i < tab.length; i++);
System.out.println("Enter number for array ");
tab [] = read.nextInt();
Please help. I'm a total newbie in programming.
You should do your homework yourself ;)
Scanner read = new Scanner(System.in);
int[] tab = new int [100];
int idx=0;
do{
System.out.println("Number for array idx "+idx);
try{
tab[idx] = read.nextInt();
}catch(Exception e){
System.out.println("Wrong input");
}
if(tab[idx]<0) break;
idx++;
}while(idx<100)
Not compiled, just wrote it here.
Try that
public static void main(String[] args) {
Scanner read = new Scanner(System.in);
int[] tab = new int [100];
int index = 0;
while(index < tab.length){
System.out.println("Enter number for array ");
tab[index]= read.nextInt();
if(tab[index]<1) break;
index++;
}
System.out.println(Arrays.toString(tab));
}
Related
Below is the code. After entering the array, the console just goes blank and does not further output the array:
import java.util.Scanner;
public class advancedArrays {
public static void main(String[] args) {
System.out.println("Provide us the size of the array:");
Scanner scanner = new Scanner(System.in);
int value = scanner.nextInt();
int i = 0;
int[] array = new int[value];
System.out.println("Enter the array:");
Scanner input = new Scanner(System.in);
while(input.hasNextInt()) {
array[i] = input.nextInt();
i++;
}
System.out.println("Array entered:");
for(i=0;i<value;i++)
{
System.out.println(array[i]);
}
input.close();
scanner.close();
}
}
Output:
Provide us the size of the array:
5
Enter the array:
1 2 3 4 5
you are stuck in the "reading the array" part because of this
while (input.hasNextInt()) {
array[i] = input.nextInt();
hint: you know the size of the array, then why don't you do a for loop same as you did for printing out the array's content?? like:
for (int j = 0; j < value; j++) {
array[i] = scanner.nextInt();
i++;
}
The problem is that with the while loop that you keep it waiting for more integers, it is better to convert to a normal for loop with condition on the entered array size value.
Also there is no need to use two scanner objects
public static void main(String[] args) {
System.out.println("Provide us the size of the array:");
Scanner scanner = new Scanner(System.in);
int value = scanner.nextInt();
int i = 0;
int[] array = new int[value];
System.out.println("Enter the array:");
for (int j = 0; j < value; j++) {
if (scanner.hasNextInt()) {
array[i] = scanner.nextInt();
i++;
}
}
System.out.println("Array entered:");
for (i = 0; i < value; i++) {
System.out.println(array[i]);
}
scanner.close();
}
package Main;
import java.util.Scanner;
public class advancedArrays {
public static void main(String[] args) {
System.out.println("Provide us the size of the array:");
Scanner scanner = new Scanner(System.in);
int value = scanner.nextInt();
int i = 0;
int[] array = new int[value];
System.out.println("Enter the array:");
Scanner input = new Scanner(System.in);
while(input.hasNextInt()) {
array[i] = input.nextInt();
i++;
//Changed Code
if (i == value) {
break;
}
}
System.out.println("Array entered:");
for(i=0;i<value;i++)
{
System.out.println(array[i]);
}
input.close();
scanner.close();
}
}
Fixed code, you were stuck reading your inputs for your array because you never checked if your inputs were the length of your array.
Fixed code.
if (i == value) {
break;
}
I'm making a program for my assignment. This is not the whole program but it's just a part of it.
I want from the user to enter some integer values to be stored in "items" arrays. When the user input "stop" the loop should close and here is the problem.. when I write stop the program stops and give me some errors.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int i=0, lines=1;
int[] items = new int[100];
int total = 0;
System.out.println("Enter the items with its price");
while(true){
i=i+1;
if ("stop".equals(scan.nextLine()))
break;
else
items[i] = scan.nextInt();
}
}
There are certain mistakes in your code. It's more better if you could just add the error.
Try this code.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int i = 0, lines = 1;
int[] items = new int[100];
int total = 0;
System.out.println("Enter the items with its price");
while(true){
String InputTxt = scan.nextLine();
if (InputTxt.equals("stop"))
break;
else{
try{
items[i] = Integer.parseInt(InputTxt);
i++;
}catch(Exception e){
System.out.println("Please enter a number");
}
}
}
}
On top of other answers, I would like to advise you to change the looping from
while(true)
to
//first you need to remove the local variable i
for(int i = 0; i < items.length; ++i)
Using this approach will help you to avoid IndexOutOfBoundsException when users key in more than 100 integer values.
your problem is this line : items[i] = scan.nextInt(); because you are trying to get integer while the input is string stop
EDIT
one possible solution is that you get your data as string and check if it is stop or not and if not then try to parse it to integer like code bellow:
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int i=0, lines=1;
int[] items = new int[100];
int total = 0;
System.out.println("Enter the items with its price");
while(true)
{
i=i+1;
String str = scan.nextLine()
if ("stop".equals(str))
break;
else
{
items[i] = Integer.parseInt(str)
}
}
}
i am working on a program to add numbers using an array. I have completed a lot of it but am troubled at the last part adding the actual numbers in the code. Here is my code.
public static void main (String[] args) {
Scanner input= new Scanner(System.in);
System.out.println("Enter size of array");
int n= input.nextInt();
int[] x= new int[n];
System.out.println("Enter Array nums");
for(int i=0;i<n;i++){
x[i]= input.nextInt();
}
}
You just need to initial variable with 0 which will have a sum of all values and then while taking a input the values are added into the variable initialized for holding the total values in the same for loop.
Given below is the code for the same.
public static void main(String args[]){
Scanner input= new Scanner(System.in);
System.out.println("Enter size of array");
int n= input.nextInt();
int[] x= new int[n];
System.out.println("Enter Array nums");
int total=0;
for(int i=0;i<n;i++){
x[i]= input.nextInt();
total=total+x[i];
}
System.out.println("total"+total);
}
Why not just write some code to add numbers?
import java.util.Scanner;
class X {
public static void main (String[] args) {
Scanner input= new Scanner(System.in);
System.out.println("Enter size of array");
int n= input.nextInt();
int[] x= new int[n];
System.out.println("Enter Array nums");
for(int i=0;i<n;i++){
x[i]= input.nextInt();
}
int sum = 0;
for(int i=0;i<n;i++){
sum+= x[i];
}
// to print the result, uncomment the line below
//System.out.println(sum);
}
}
here is a method that will add up your array for you:
public int totalArray(int[] someArray) {
int reply = 0;
for (int value : someArray) reply += value;
return reply;
}
I was wondering how to load up an array (with user input) using a while loop. The code below prints a 0.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int i = 0;
int n = 0;
int[] myArray = new int[10];
System.out.printf("enter a value>>");
while (scan.nextInt() > 0) {
for (i = 0; i > 0; i++) {
myArray[i] = scan.nextInt();
}
System.out.printf("enter a value>>");
}
System.out.printf("array index 2 is %d", myArray[2]);
}
There are multiple things wrong with your code:
First of all
while(scan.nextInt() > 0){
Scanner.nextInt() returns an int from your standard input so you actually have to pick up that value. You are checking here what the user typed but then not using it at all and storing the next thing that the user types by saying:
myArray[i] = scan.nextInt();
You don't really need the outer while loop, just use the for loop, its enough.
However, your for loop is off as well:
for(i = 0; i > 0; i++){
It starts at i equal to 0 and runs while i is greater than 0. This means it will never actually run the code within the loop because 0 is never greater than 0. And if it did run (you started it at some number < 0), you would end up in an infinite loop because your condition i > 0 is always true for positive numbers.
Change the loop to:
for(i = 0; i < 10; i++){
Now, your loop could look like:
for(i = 0; i < 10; i++){ // do this 10 times
System.out.printf("enter a value>>"); // print a statement to the screen
myArray[i] = scan.nextInt(); // read an integer from the user and store it into the array
}
one other way to do it
Scanner scan = new Scanner(System.in);
List list = new ArrayList();
while(true){
System.out.println("Enter a value to store in list");
list.add(scan.nextInt());
System.out.println("Enter more value y to continue or enter n to exit");
Scanner s = new Scanner(System.in);
String ans = s.nextLine();
if(ans.equals("n"))
break;
}
System.out.println(list);
public static void main(String[] args)
{
Scanner input =new Scanner(System.in);
int[] arr=new int[4];
int i;
for(i=0;i<4;i++)
{
System.out.println("Enter the number: ");
arr[i]=input.nextInt();
}
for(i=0;i<4;i++)
{
System.out.println(arr[i]);
}
}
Hope this code helps.
does anyone know how to set a user input for an array, I cant find the command anywhere. my array 'grades' have 20 locations. im not so sure about 'grades.length' function but I think it prompts 20 times. BUT I added a while statement to override BUT ITS TOTALLY IGNORING THE FOR STATEMENT. if I could set user input for array I could get rid of the while statement...
program has to accept grade for number of students the user inputs btw..
import java.util.Scanner;
public class gradesaverage {
public static void main(String[] args) {
int [] grades = new int [20];
int i;
int numStudents;
System.out.print("Enter number of students: ");
Scanner scanint = new Scanner (System.in);
numStudents = scanint.nextInt();
for ( i = 1; i <= grades.length; ++i)
{
System.out.println("Enter grade: ");
grades[i] = scanint.nextInt();
}
while(i <= numStudents );
}
}
Not sure what you mean, but assuming all input is correct,
int [] grades = new int [numStudents ];
Should work if you move this line after declaration and assignment of numStudents. There is no problem in java with variable length arrays.
Also note - your iterator i starts from 1, while in java arrays start from 0.
public static void main(String[] args) {
int i;
int numStudents;
System.out.print("Enter number of students: ");
Scanner scanint = new Scanner (System.in);
numStudents = scanint.nextInt();
int [] grades = new int [numStudents]; //the size we wanted
for ( i = 0; i < grades.length; ++i) //starting from 0, not 1.
{
System.out.println("Enter grade: ");
grades[i] = scanint.nextInt();
}
//print the array - for checking out everyting is ok
System.out.println(Arrays.toString(grades));
}