CODEWITHSUNDEEP
javaarrays2dassign
Sam Prescott
Sam Prescott

Reputation: 55

Value in array not not assigned - java

My 2D array is not being assigned values as it should. The method is called here:

public static void inputPair() throws IOException {
    System.out.println("Enter symbol which you want to pair letter to:");
    char s = 'a';
    while (s == 'a') {
        try {
            s = input.next(".").charAt(0);
        } catch (InputMismatchException e) {
            System.out.println("Please enter a valid symbol!");
            input.next();
        }
    }

    System.out.println("Enter letter which you want to pair symbol to:");
    char l = '#';
    while (l == '#') {
        try {
            l = input.next(".").charAt(0);
        } catch (InputMismatchException e) {
            System.out.println("Please enter a valid letter!");
            input.next();
        }
        if ((s <= 'a') && (s >= 'z')) {
            System.out.println("Please enter a valid letter!");
            l = '#';
        }
    }
    makePair(s, l);
    System.out.println("Pair made!");
}

and the makePair method: 

public static void makePair(char s, char l) {
    for (int i = 0; i < words.length; i++) {
        words[i] = words[i].replace(s, l);
    }
    try {
        pairings[findFree()][0] = Character.toString(l);
        pairings[findFree()][1] = Character.toString(s);
    } catch (Exception e) {
        System.out.println("Please start again!");
        System.exit(0);
    }
}

This should assign the value of l and s into the 2D array at the first empty cell due to the findFree method:

public static int findFree() {
    for (int i = 0; i < pairings.length; i++) {
        if (pairings[i][0] == null) {
            return i;
        }
    }
    return 27; // Greater than 26
}

However the cell remains having the value of null.

Upvotes: 0

Views: 705

Answers (1)

Bohuslav Burghardt
Bohuslav Burghardt

Reputation: 34796

I'm not sure that this is the only problem, but it seems wrong:

pairings[findFree()][0] = Character.toString(l);
pairings[findFree()][1] = Character.toString(s);
  1. findFree() will find index of an array in the pairings 2D array whose value at index 0 is null, let's say it's 0.
  2. Value of l will be assigned to [0][0]
  3. You call findFree() again - pairings[0] will not be selected, because it already contains l (which is not null) at index 0, so the next one will be selected (let's say 1)
  4. Value of l will be assigned to [1][1].

Thus you will end up with [l][null] and [null][s], instead of the desired [l][s] (at least I assume that this is the result you want).

To fix it do something like this:

int freeIndex = findFree();
pairings[freeIndex][0] = Character.toString(l);
pairings[freeIndex][1] = Character.toString(s);

Upvotes: 1

Related Questions