java - Summing the results of an array multiplication -

i need sum result of multiplication of these 2 arrays:

              item  store   0   1   2   3    4  0      25  64  23  45  14  1      12  82  19  34  63  2      54  22  17  32  35  item     cost per item    0           $12.00    1           $17.95    2           $95.00    3           $86.50    4           $78.00 

i have sum results of first row, second row, , third row , display them separately , add them up. code i'm using program following:

import java.util.*; public class asd {     public static void main(string[] args)     {         double items[][]= new double[3][5];         double cost[]=new double[5];         loadarray(items, cost);         system.out.println("total amount of sales each store : ");         computecost(items, cost);         printarray(items, cost);     }     public static void loadarray(double items[][], double cost[])     {         scanner input = new scanner(system.in);         string s1;         int num, x, y;         for(x=0; x<items.length;x++)         {             for(y=0; y<items[x].length; y++)             {                 system.out.println("enter next item of data:");                 items[x][y]=input.nextdouble();             }         }          //cost of items:         cost[0]=12.00;         cost[1]=17.95;         cost[2]=95.00;         cost[3]=86.50;         cost[4]=78.00;     }     public static void printarray(double items[][], double cost[])      {         system.out.println("number of items sold during day: ");         int row, col;         (row =0;  row<items.length ; row++)         {             for(col=0; col<items[row].length; col++)             {                 system.out.print( items[row][col]+" ");             }             system.out.println();         }         system.out.println("cost per item: ");         int i;         (i =0; < 5; i++)         {             system.out.println(cost[i]);         }     }     public static void computecost (double items[][], double cost[])     {         int row, col;         double productarray[]=new double[3];         (row =0;  row<items.length ; row++)         {             for(col=0; col<items[row].length; col++)               {                 if(col==0)                 {                     productarray[row]=items[row][col]*cost[0];                     system.out.println(productarray[row]+" test1 ");                 }                 else if(col==1)                 {                     productarray[row]=items[row][col]*cost[1];                     system.out.println(productarray[row]+" test2 ");                 }                 else if(col==2)                 {                     productarray[row]=items[row][col]*cost[2];                     system.out.println(productarray[row]+" test3");                 }                 else if(col==3)                 {                     productarray[row]=items[row][col]*cost[3];                     system.out.println(productarray[row]+" test4 ");                 }                 else if(col==4)                 {                     productarray[row]=items[row][col]*cost[4];                     system.out.println(productarray[row]+" test5 ");                 }                         }         }     } } 

the computecost() method multiplication takes place, i'm wondering how can store values of multiplication can later add them up.

(for example output of computecost() method first run :

300.0 test1  1148.8 test2  2185.0 test3 3892.5 test4  1092.0 test5  

i need way store values , add them up, since they're inside of loops , if statements, i'm not sure of how that.

any appreciated.

you there already. going wrong overwriting value @ index particular row @ each new column. should increment value instead. possible use same variable each row (instead of array), because don't reuse saved value in way.

also, not needed create if-else structure did checking column considering. can generalize part using value of col variable instead.

the new computecost() method this:

public static void computecost (double items[][], double cost[]) {     (int row = 0; row < items.length; row++) {         double rowsum = 0.0;         for(int col = 0; col < items[row].length; col++) {             double colproduct = productarray[row] = items[row][col] * cost[col];             rowsum += colproduct;             system.out.println("row: " + row + ", col: " + col + ": " + colproduct);         }          system.out.println("total row " + row + ": " + rowsum);     } }