Exception in CoinChangeProblem code

Question

import java.io.*;

public class CoinChangeProblem {

public static void main(String[] args) throws IOException {
    // TODO Auto-generated method stub
    int[] arr;
    arr = new int[]{1, 2, 5, 10, 20, 50, 100, 500, 1000};
    int[] arr2;
    arr2 = new int[]{-1, -1, -1, -1, -1, -1, -1, -1, -1};
    int max_coin = 0, due, i = 0, j = 0;
    BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in));
    System.out.print("\n\n\tEnter the amount of currency due");
    due = Integer.parseInt(stdin.readLine());
    while (due != 0) {
        for (j = 0; due > arr[j] && j < 9; )
            max_coin = arr[j++];
        j = 0;
        arr2[i] = max_coin;
        due = due - max_coin;
        i += 1;
    }
    i = 0;
    for (int k = 0; arr2[k] != -1; k++) {
        System.out.print(" " + arr2[k]);
    }
}
}

The compiler is throwing ArrayIndexOutOfBoundsException at line 9 and 23.If you have got a solution please help!

score 0 · Accepted Answer · answered Nov 08 '17 at 20:32

0

Last iteration of your for loop makes arr2[i] = max_coin access arr2[9] but your array's last index is 8.

answered Nov 08 '17 at 20:32

Bobzone

276
2
12

Yeah I added a condition to restraint I up to 8 index and it is working fine,although logic has a hole itself,anyways thank you for ur kind help ☺ – learner Nov 09 '17 at 02:32

score 0 · Answer 2 · answered Nov 08 '17 at 20:36

0

Change your loop as

for(j=0; j<9 && due>arr[j];)
    max_coin=arr[j++];

Java works with short circuiting, therefore when you check if j is smaller than 9 first, then it will be false and loop ends.

answered Nov 08 '17 at 20:36

small_ticket

1,910
5
22
30

Thank you so much for your response ,I didn't know about this concept until now ☺ – learner Nov 09 '17 at 02:37

Kayvan Tehrani · Answer 3 · 2017-11-08T21:17:03.980

0

This program gets an input variable from standard input which is stored in 'due' local variable. It just works when the 'due' input is <= 7. If the input value is greater than 7 this exception raises:

Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 9 at CoinChangeProblem.main(CoinChangeProblem.java:23)

Pay attention the '9' is not the line number, it indicates given index which is more than the max size of your array. The size of 'attr2' array is 9 and it supports [0-8] indexes. So when 'i' variable reaches to number 9, then 'arr2[i]' expressions causes the ArrayIndexOutOfBoundsException.

edited Nov 08 '17 at 21:17

answered Nov 08 '17 at 20:57

Kayvan Tehrani

3,070
2
32
46

Yeah I fixed that statement and it is working now.Thankyou for your help ☺ – learner Nov 09 '17 at 02:34
@nishant you are welcome, if it helped you can select the answer as solution or give it a plus. – Kayvan Tehrani Nov 09 '17 at 08:32

Exception in CoinChangeProblem code

3 Answers3