CODEWITHSUNDEEP
javalistarraylistinputcollections
user6123563
user6123563

Reputation:

Add input into list

I'm trying to add user's input into list and then show it in reverse order. The elements are added until the user enters 0. Here's my code:

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Scanner;

public class InputInArrrayList{
    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int a = s.nextInt();
        List<Integer> myList = new ArrayList<>();
        while(a > 0) {
            myList.add(a);
            if (a == 0){
                break;
            }
        }
        Collections.reverse(myList);
        System.out.println(myList);
    }
}

But the loop doesn't break when it's 0. Instead, it throws OutOfMemoryError: Java Heap space. What am I doing wrong?

Upvotes: 3

Views: 104

Answers (4)

akshaya pandey
akshaya pandey

Reputation: 997

Currently , you are getting into an infinite loop as a gets set to the first number and then keeps looping, thus, keeps adding same number to the list. you need to add inside the while loop. int a = s.nextInt();

Upvotes: 0

Anastasios Vlasopoulos
Anastasios Vlasopoulos

Reputation: 1802

Your problem is the below code:

while(a > 0) {
    myList.add(a);
    if (a == 0){
        break;
    }
}

As you can see after reading the first user input and assigning it to a, the the while loop is running infinitely. This happens because the condition argument which is the a variable never changes.
So you have to insert the part of code that updates that variable inside the while loop. Below is a simple fix:

Scanner s = new Scanner(System.in);
int a = 1;
List<Integer> myList = new ArrayList<>();
while(a > 0) {
    a = s.nextInt();
    if (a == 0) {
        break;
    } else {
        myList.add(a);
    }        
}

Upvotes: 0

Karan
Karan

Reputation: 448

Please correct your loop

List<Integer> myList = new ArrayList<>();
while(true) {
    int a = s.nextInt();
    if (a == 0){
        break;
    }  else
        myList.add(a);
    }

Upvotes: 0

Pramod S. Nikam
Pramod S. Nikam

Reputation: 4549

at least one a >= 0 needed for break to execute: 

   while(a >= 0) {
        myList.add(a);
        if (a == 0){
            break;
        }
    }

Upvotes: 1

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