How to write a method for multidimensional array

Question

I want to write a method for selecting a specific year (say 2009) from the Time array.

This would refer (8001) which is basically a key for year 2009.

In the FactTable I would like to add all the figures which represent quantity (the 1s). So it would show sales total for year 2009. Anyone have a clue how i can do this.

The Time array stores {timekey, year, month, week, day}

The FactTable stores {clientid, Vehicleid, branchid, timekey, quantity, profit}

 int[][] Time = new int[][] 
        {{8001,2009,1,1,1},
        {8002,2010,1,1,7},
        {8003,2011,1,1,5},
        {8004,2012,1,1,5}};


int[][] FactTable = new int [][]
        {{1,125,20,8001,1,2000},
        {2,126,40,8001,1,1500},
        {3,127,50,8001,1,2500},
        {4,128,10,8001,1,2500}};

int sum = 0; 

int year = 8001;



for (int i = 0; i< FactTable.length-1; i++)
{
    for (int j = 1; j < FactTable[i].length-1; j++)
    {
        year = year + FactTable + [0][4];

    }

}
System.out.println (year);

I didn't understand what you want but your syntax has error in year = year + FactTable + [0][4]; ... you couldn't write it [0][4] .. you can write FactTable[0][4] or FactTable[i][j] — Tareq Salah
– Tareq Salah, Commented Dec 19, 2013 at 21:40
First, your loop is off by one; use i < FactTable.length and not i < FactTable.length - 1. The latter will skip the last entry. The latter would be correct if you made the condition <= instead of <. Secondly, please consider using a data structure to store this information instead of a multidimensional array. In other words write a Fact class which has ClientId, VehicleId, etc. properties. This will make your code much more readable, maintainable and less error-prone. — TypeIA
– TypeIA, Commented Dec 19, 2013 at 21:42
@user3119757 you want a method that returns mapping between YEAR and timeKey ryt?? — Mitesh Pathak
– Mitesh Pathak, Commented Dec 19, 2013 at 21:57

JosefN · Accepted Answer · 2013-12-19 21:45:02Z

2

following code shows how to address fields in multidimensional array

int sum = 0; 
int year = 8001;
for (int i = 0; i< FactTable.length; i++)
    {
       if (FactTable[i][3] == year) {
           sum = sum + FactTable[i][4];
       }
    }
System.out.println(sum);

please note correction of second expression in for loop

answered Dec 19, 2013 at 21:45

JosefN

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Comments

Mr_and_Mrs_D · Accepted Answer · 2013-12-19 23:37:24Z

1

public class Test1 {

    public static void main(String[] args) {
        int[][] timeTable = new int[][] { { 8001, 2009, 1, 1, 1 },
                { 8002, 2010, 1, 1, 7 }, { 8003, 2011, 1, 1, 5 },
                { 8004, 2012, 1, 1, 5 } };
        int[][] factTable = new int[][] { { 1, 125, 20, 8001, 1, 2000 },
                { 2, 126, 40, 8001, 1, 1500 }, { 3, 127, 50, 8001, 1, 2500 },
                { 4, 128, 10, 8001, 1, 2500 } };
        meth(factTable, 2009, timeTable);
    }

    private static void meth(int[][] factTable, int year, int[][] timeTable) {
        int timeKey = -1;
        // find the timeKey from the year
        for (int[] is : timeTable) { // for each row in timeTable
            if (is[1] == year) { // if the year column (duh) is the year
                timeKey = is[0]; // get the timekey
                break; // we're done
            }
        }
        if (timeKey == -1) return; //timeKey still -1: no timeKey for year
        int sum = 0;
        for (int[] js : factTable) { // for each row in factTable
            if (js[3] == timeKey) { // if the timeKey column is right
                sum += js[4]; // add to the sum the quantity
            }
        }
        System.out.println(sum); // done
    }
}

Although I really do not get what are those arrays for

edited Dec 19, 2013 at 23:37

answered Dec 19, 2013 at 21:48

Mr_and_Mrs_D

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10 Comments

user3119757 Over a year ago

what exactly is this doing, when i run this it dont print anything?

Mr_and_Mrs_D Over a year ago

@user3119757: Run it again - there was a typo - added some comments

user3119757 Over a year ago

It didnt solve it I was looking for the result to be 4 which is the qantity of sales for 2009.

Mr_and_Mrs_D Over a year ago

@user3119757: but in FactTable you have 8001 in all rows

user3119757 Over a year ago

Yeah that means they all purchased it in 2009

|

Mitesh Pathak · Accepted Answer · 2013-12-19 22:06:28Z

0

I hope this helps

int year = 2009;
int timeKey = -1;

for (int array[] : Time) {
    if (array[1] == year) {
        timeKey = array[0]; 
        break;
    }
}

int sum = 0;

for (int array[] : FactTable) {
    if (array[3] == timeKey) {
        sum += array[4]; 
    }
}

System.out.println(sum);

answered Dec 19, 2013 at 22:06

Mitesh Pathak

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1 Comment

Mitesh Pathak Over a year ago

@Mr_and_Mrs_D got it first :)

Nilsaw · Accepted Answer · 2013-12-19 21:54:34Z

0

You can probably do this: A simplified solution for finding the sum of the values,

int sum=0
for (int i = 0; i< FactTable.length; i++){

         if(FactTable[i][3]==8001){
              sum+=FactTable[i][4]
            }        

}

answered Dec 19, 2013 at 21:54

Nilsaw

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Comments

Community · Accepted Answer · 2017-05-23 11:50:16Z

0

Array indices are accessed by making a call like so:

Object indexObject = array[index];

You indicate the index, surrounded by square-brackets, immediately following the name of the array.

You code should look like below:

for (int i = 0; i< FactTable.length-1; i++)
{
    for (int j = 1; j < FactTable[i].length-1; j++)
    {
        year = year + FactTable[0][4];  //This is how you access indices of an array.
    }

}

Accessing the indices of multidimensional arrays is not different that accessing the indices of a single-dimension array since the first index of a multidimensional array will return another array with one less dimension. To demonstrate:

Object[][][] array3 = new Object[1][1][1];  //This is a three dimensional array.
Object[][] array2 = array3[0];              //array3[0] returns a two dimensional array.
Object[] array1 = array3[0][0];             //array3[0][0] returns a one dimensional array.

To add together multiple indices of an array, an operation is performed like below:

int a = array[0][4];
int b = array[1][4];
int c = array[2][4];
int d = array[3][4];
int result;

//The two operations below are functionally the same.
result = a + b + c + d;
result = array[0][4] + array[1][4] + array[2][4] + array[3][4];

Aside from the lesson on how to access arrays, JosefN's answer is likely the solution to your problem.

edited May 23, 2017 at 11:50

CommunityBot

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answered Dec 19, 2013 at 21:43

Taylor Hx

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2 Comments

user3119757 Over a year ago

Thanks for your responce, how would i add together 0,4 1,4 2,4 3,4

Taylor Hx Over a year ago

@user3119757 No thanks necessary. Just be sure to mark JosefN's answer as correct if it helped you.

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