Is it possible to assign an array to a two-dimensional array?

Question

I am making an expense tracker program for an assessment project, but the thing is, the question sheet is too vague. One of the problems is that, I am not sure if I should just stick to a one-dimensional array or a multi-dimensional one.

The whole idea is that; a user selects a month and it will prompt an option that allows user to assign the expense to that month and to a certain item. It would look some thing like this:

Enter month (1 for Jan - 12 for Dec): 1

Jan expenditure(max 10 items) Enter item 1 (Press ENTER to exit): fast food

Enter amount : $10

What kind of dimensional array should I used? It seems that as I progress into the different dimension of arrays, it kinda like open up a can of worms.

So far, I have gotten this:

  int m = 12;
int exp = 10;

int[][] month = new int [m][exp];


public void data(){


}



public void monthlyExp(){
    String[] mth = {"Jan", "Feb", "Mar", "Apr",
            "May", "Jun", "Jul", "Aug", "Sep",
            "Oct","Nov","Dec"
    };

    System.out.print("Enter month > ");
    int mon = input.nextInt();

    for (int i = 0; i < month.length; i++){
        System.out.println();
        if (i == (mon-1)){
            System.out.println(mth[i] + " expenditure <max 10 items>");
            while (true){
                for (int h = 0; h < exp; h++);
                System.out.print("Enter item " + (h + 1) + "(PRESS ENTER TO EXIT)");
            }

There are somethings called "Classes and Objects" in Object oriented programming. Use them. — Rohit Jain, Jan 16 '14 at 09:58
@RohitJain Hi, I've just learnt about classes and objects recently before I've asked this question. Turns out I'm way too early to start my assignment thanks! — user3201898, Jan 24 '14 at 14:42
@TheLostMind Hi, I've learnt that it's simpler to use an arrayList instead of array but thanks for your answer! — user3201898, Jan 24 '14 at 14:43

score 0 · Answer 1 · answered Jan 16 '14 at 10:25

0

One approach is to create a POJO class with attributes for the month, expense, and description of expense, and have a single array of your POJO objects. If you find the confusing, try using parallel arrays or better yet ArrayLists. That is, have a separate array for each of month, expense, and description. Each time you have a new entry in your ledger, add an element to each of the arrays, using the same index, then increment the index for the next entry.

answered Jan 16 '14 at 10:25

Teresa Carrigan

668
8
14

It's quite lengthy to do the latter method but yes, I shall take that into consideration. Thanks! – user3201898 Jan 24 '14 at 14:41

score 0 · Answer 2 · answered Jan 16 '14 at 10:49

public static void main(String[] args) {
    int[] arr = new int[5];
    int[][] newArr = new int[5][5];
    // arr = newArr;    compile time error 
    // newArr = arr;    compile time error
    newArr[0]=arr;    // valid. But this is not preferred and is considered a bad practice. You might run into trouble later on with this little piece of code. So use Objcts/collections whereever possible instead of arrays.

    for(int i=0;i<5;i++)
    {
        newArr[0][i]=i;  // ArrayIndexOutOfBoundsException at runtime (arr has size of 5 remember?). So, be wary of such assignments. Everything seems fine until it breaks. 
    }
}

Is it possible to assign an array to a two-dimensional array?

Enter month (1 for Jan - 12 for Dec): 1

Enter amount : $10

2 Answers2