How do I add user input to an Array in java? - java

public static void main(String[] args) {
Scanner user_input = new Scanner(System.in);
int i;
int n;
String a;
System.out.println("Enter the Class:");
a = user_input.next();
System.out.println("Enter the number of Students:");
n = user_input.nextInt();
for (i= 1; i <= n; i++) {
String g = a + i;
System.out.println(g);
}
}
This is my program. It gets user input for the Class and prints the Roll Number for the students.
For example: If the class is 10A and the number of students is 10, it prints a series like 10A1 , 10A2, 10A3 ... 10A10
How do I get the program to store these as elements in an array?
For example:
array[0] = 10A1;
array[1] = 10A2;
array[2] = 10A3;
etc.

Your code should look like this:
public static void main (String args[])
{
Scanner user_input = new Scanner(System.in);
int i;
int n;
String a;
System.out.println("Enter the Class:");
a = user_input.next();
System.out.println("Enter the number of Students:");
n = user_input.nextInt();
String []strings = new String[n]; // Creating an are of string with the given number
for(i= 0; i < n ;){
strings[i] = a + ++i; // Storing strings on to the array !
System.out.println(strings[i-1]);
}
}

You can just edit each index in your current for loop:
String[] arr;
for(i=0; i < n ; i++){
int j = i+1;
String g = a + j;
System.out.println(g);
arr[i] = g;
}
So all your printed g's will be part of the array arr.

First, declare a String array of the appropriate size.
Second, in your for loop, assign the strings you are currently printing, to positions in the array.
String[] things = new String[n];
for (i=1; i <= n; i++) {
String g = a + i;
System.out.println(g);
things[i-1] = g;
}
The strings are now in an array.

Following code is modified, for storing values in array.
public static void main(String[] args) {
// TODO code application logic here
Scanner user_input = new Scanner(System.in);
int i;
int n;
String a;
System.out.println("Enter the Class:");
a = user_input.next();
System.out.println("Enter the number of Students:");
n = user_input.nextInt();
String[] arr = new String[n]; // create string array of size n.
for(i= 1; i <= n ; i++){
String g = a + i;
System.out.println(g);
arr[i-1]=g; // assign your g veriable vale to array index
}
for(String s : arr){
System.out.println(s); // print your array
}
}

Related

I have to print the array , but for each loop is not working

import java.util.Scanner;
public class TeacherCoins {
public static void main(String[] args){
int k;
System.out.print("Enter total number of coins :");
Scanner sc = new Scanner(System.in);
k =sc.nextInt();
int [] arr= new int[k-1];
System.out.print("Enter array :");
for(int i=0;i<=(k-1);i++)
{
Scanner sc1 = new Scanner(System.in);
arr[i] =sc1.nextInt();
}
for(int element :arr)
{
System.out.println("Print array");
System.out.println(element);
}
}
I am giving output using Scanner class. But is not printing the array.
You don't need to declare the Scanner again inside the loop. Another thing that you should do to be sure of your code, is to have this condition on the loop if i < arr.length. Lastly, I moved the "Print array" message outside the last for.
public class TeacherCoins {
public static void main(String[] args){
int k;
System.out.print("Enter total number of coins :");
Scanner sc = new Scanner(System.in);
k =sc.nextInt();
int [] arr = new int[k];
System.out.print("Enter array :");
for(int i=0; i<arr.length; i++) {
arr[i] =sc1.nextInt();
}
System.out.println("Print array");
for(int element :arr){
System.out.println(element);
}
}
}
There are two problems with this code,
1. You don't need to create a new Scanner object for each user input.
2. You are declaring an array size of k-1 and then asking user input k times.
public static void main(String[] args) {
int k;
System.out.print("Enter total number of coins :");
Scanner sc = new Scanner(System.in);
k = sc.nextInt();
int[] arr = new int[k]; // To store k elements, you need k sized array
System.out.print("Enter array :");
for (int i = 0; i <= (k - 1); i++) {
// Scanner sc1 = new Scanner(System.in); / / Not required here
arr[i] = sc.nextInt();
}
System.out.println("Print array");
for (int element : arr) {
System.out.println(element);
}
}
There is only one problem in your code you are declaring the size of array as k-1 instead declare it for k elements.You just need to give each inputs in new line. For more refer this :Scanner class.
And your for each loop is correct and working.
import java.util.Scanner;
public class TeacherCoins {
public static void main(String[] args){
int k;
System.out.print("Enter total number of coins :");
Scanner sc = new Scanner(System.in);
k =sc.nextInt();
int [] arr= new int[k];//it was giving java.lang.ArrayIndexOutOfBoundsException
System.out.print("Enter array :");
for(int i=0;i<=(k-1);i++)
{
Scanner sc1 = new Scanner(System.in);//not required
arr[i] =sc1.nextInt();//use arr[i] =sc.nextInt();
}
for(int element :arr)
{
System.out.println("Print array");
System.out.println(element);
}
}
}
Above code will work. But you don't need new scanner objects for taking input, creating only single object will work.
import java.util.Scanner;
public class TeacherCoins {
public static void main(String[] args) {
int k;
System.out.print("Enter total number of coins :");
Scanner sc = new Scanner(System.in);
k = sc.nextInt();
int[] arr = new int[k];
System.out.print("Enter array :");
for (int i = 0; i < arr.length; i++) {
arr[i] = sc.nextInt();
}
sc.close();
System.out.println("Print array");
for (int element : arr) {
System.out.println(element);
}
for (int i = 0; i < arr.length; i++) {
int count = 0;
for (int j = 0; i < arr.length; j++) {
arr[i] = arr[j];
count++;
}
System.out.println(arr[i] + " " + count);
}
}
}

Multiplication based on input integer and return array- Need help in storing array while looping

Do multiplication based on user input integer and return array in Java.
Eg: User Input 2
1*1=1
1*2=2
2*1=2
2*2=4
Output array should have [1,2,2,4]
Scanner scan = new Scanner (System.in);
int value = scan.nextInt();
int totalSize= value * value ;
int [] a= new int [totalSize];
for(int i=1; i<=totalSize;i++)
{
for(int j=1;j<=value ;j++)
{
a[i-1]=i*j;
}
How to proceed ?
Try this
System.out.println("Enter number of entries");
Scanner scan = new Scanner (System.in);
int i,j,k,index=0;
int value = scan.nextInt();
int totalSize= value * value ;
int [] a= new int [totalSize];
for(i=1; i<=value;i++) {
for (j = 1; j <= value; j++) {
a[index++] = i * j;
}
}
for(k=0; k<totalSize;k++) {
System.out.println(a[k]);
}

return array from one method to another method

This is my program and every time it is asking me to input the array.
I want to input a array once and process on that array.
But this program is asking me to input array again.
from method named "first" I just want to return array and use that array in two different methods add and delete. But it is always asking me to input all the elements of array that is every time the first method is running while i call any add or delete method from main method.
package Program;
import java.util.Arrays;
import java.util.Scanner;
public class Functionality {
public static int[] first( )
{
System.out.println("Enter the number of element in array");
Scanner num = new Scanner(System.in);
int data = num.nextInt();
//return data;
Scanner ar = new Scanner(System.in);
int arr[] = new int[data];
System.out.println("Enter "+data+" Numbers");
for(int i =0; i<data; i++){
System.out.println("Enter NUmber :"+(i+1));
arr[i] = num.nextInt();
}
System.out.println();
System.out.println(Arrays.toString(arr));
return arr;
}
public static void main(String[] args) {
add();
delete();
}
static void add(){
int arr[]=first();
System.out.println("Enter the number you want to add");
Scanner one = new Scanner(System.in);
int naya = one.nextInt();
for(int i = 0; i<=arr.length-1; i++){
arr[i]= arr[i] + naya;
}
System.out.println("The added array is");
System.out.println(Arrays.toString(arr));
}
static void delete(){
int arr[]=first();
System.out.println("Enter the number you want to substract");
Scanner two = new Scanner(System.in);
int arko = two.nextInt();
for(int i =0; i <= arr.length-1; i++ ){
arr[i]=arr[i]-arko;
}
System.out.println("The Substracted array is");
System.out.println(Arrays.toString(arr));
}
You should obtain reference to an array and passing it during subsequent methods invocations.
This should do the trick:
class Functionality {
static int[] first() {
System.out.println("Enter the number of element in array");
Scanner num = new Scanner(System.in);
int data = num.nextInt();
//return data;
Scanner ar = new Scanner(System.in);
int arr[] = new int[data];
System.out.println("Enter " + data + " Numbers");
for (int i = 0; i < data; i++) {
System.out.println("Enter NUmber :" + (i + 1));
arr[i] = num.nextInt();
}
System.out.println();
System.out.println(Arrays.toString(arr));
return arr;
}
public static void main(String[] args) {
int arr[] = first();
add(arr);
delete(arr);
}
static void add(int arr[]) {
System.out.println("Enter the number you want to add");
Scanner one = new Scanner(System.in);
int naya = one.nextInt();
for (int i = 0; i <= arr.length - 1; i++) {
arr[i] = arr[i] + naya;
}
System.out.println("The added array is");
System.out.println(Arrays.toString(arr));
}
static void delete(int arr[]) {
System.out.println("Enter the number you want to substract");
Scanner two = new Scanner(System.in);
int arko = two.nextInt();
for (int i = 0; i <= arr.length - 1; i++) {
arr[i] = arr[i] - arko;
}
System.out.println("The Substracted array is");
System.out.println(Arrays.toString(arr));
}
}
Your program is asking You every time to input array, because every time You invoke method first() new array is being created

Runtime Error on CodeChef KOL1506

When i compiled and ran this code on Eclipse, this runs fine but on Codechef it shows a runtime error. Can anyone help me find why it does not run on the website. The website link is: https://www.codechef.com/viewsolution/10987533
and the problem link is : https://www.codechef.com/problems/KOL1506/
import java.util.Scanner;
class SamosaBhai {
public static void main(String[] args){
int n =0;
Scanner keyboard = new Scanner(System.in);
Scanner input = new Scanner(System.in);
System.out.println("Enter number of test Cases:");
n = keyboard.nextInt();
int[] ans = new int[n];
for(int i = 0; i< n ;i++){
//no. of houses and power 'd' is stored here
String get = input.nextLine();
String[] numarray = get.split(" "); // splitting string by spaces
int num = Integer.parseInt(numarray[0]); // number of houses
int d = Integer.parseInt(numarray[1]); // power to be raised
// positions of the houses is stored here
String entry = input.nextLine();
Scanner scanner = new Scanner(entry);
int[] pos = new int[num];
for (int j= 0;j<num;j++) {
pos[j] = scanner.nextInt();
}
scanner.close();
ans[i] = postalCharge(pos, d, n);
}
keyboard.close();
input.close();
for(int p =0; p<n; p++)
System.out.println(ans[p]);
}
// function to calculate the postal charges between all the houses
public static int postalCharge(int[] location, int d, int n){
int total =0;
for (int i = 0; i<n; i++){
for(int j =0; j< n; j++){
int n1 = location[i];
int n2 = location[j];
total += Math.pow(Math.abs(n1-n2),d);
}
}
return total;
}
}

Error when looping on keyboard input

I have a loop that is supposed to store information into an array of objects, but for some reason, it always skips the first input.
public class GerbilData {
public static void main(String[] args){
Scanner keyboard = new Scanner(System.in);
System.out.println("How many different food items do the gerbils eat?");
int n1 = keyboard.nextInt();
Food[] gerbilFood = new Food[n1];
String temp;
int temp2;
int count = 1;
for (int a = 0; a < n1; a++){
gerbilFood[a] = new Food();
}
int j = 0;
while (j < n1){
System.out.println("Name of food item " + count + ":");
temp = keyboard.nextLine();
gerbilFood[j].setName(temp);
count++;
j++;
}
keyboard.nextInt() is only reading an integer from the keyboard, not reading the return character. So, when you first call keyboard.nextLine() you get the \n of the getInt().
Try this instead :
int n1 = keyboard.nextInt();
keyboard.nextLine();

Categories

Resources