how to set the contents of an array equal to the contents from a second array

Question

I'm using greedy algorithm to calculate change, I want to save the set of the coins i've used to a new aray, however I :

Exception in thread "main" java.lang.NullPointerException
    at lacy_lab_7b_2015.Lacy_Lab_7b_2015.main(Lacy_Lab_7b_2015.java:36)
Java Result: 1

from the complier.

    public class Lacy_Lab_7b_2015 {

public static Scanner input = new Scanner(System.in);// scanner object to allow user input
public static int amount;// global variable defined by user to be used to have certain value of coins added so that they wll equal this value
public static int count = 0;
final public static int[] FACE_VALUES_OF_COINS = {100, 50, 25, 10, 5, 1};
public static int[] coinsUsed;

/**
 * @param args the command line arguments
 */
public static void main(String[] args) {
    // TODO code application logic here
    amount = userAmount();
   // coinsUsed = coinsUsed(FACE_VALUES_OF_COINS,amount);

    for (int i = 0; i < FACE_VALUES_OF_COINS.length; i++) {
        int j = 0;
        if (FACE_VALUES_OF_COINS[i] < amount) {
            int count = amount / FACE_VALUES_OF_COINS[i];
           coinsUsed[j] = FACE_VALUES_OF_COINS[i];
            amount -= count * FACE_VALUES_OF_COINS[i];
        }//end if
    }//end for
    for (int i = 0; i < coinsUsed.length; i++) {
        System.out.println(coinsUsed[i]);
    }
}//end main

but on mine its line 35 and that line is : coinsUsed[j] = FACE_VALUES_OF_COINS[i]; — soldier1982, Mar 20 '15 at 03:45
final public static int[] FACE_VALUE_OF_COINS = {100, 50, 25, 10, 5, 1}; — soldier1982, Mar 20 '15 at 03:49
you just declared coinUsed as array but you did'nt assigned it with vaues? so at statement coinsUsed[j] = FACE_VALUES_OF_COINS[i]; compiler doesnt knew what is coinsUsed[0] — Naz, Mar 20 '15 at 03:53
possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — user253751, Mar 20 '15 at 06:29

score 1 · Answer 1 · answered Mar 20 '15 at 03:56

1

I whould suggest you to write

public static int[] coinsUsed;

as

public static int[] coinsUsed = new int[5];

answered Mar 20 '15 at 03:56

Naz

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how to set the contents of an array equal to the contents from a second array

1 Answers1