I have a custom class MW. MW gets 2 matrices-(ke matrix and val matrix).

And I am trying to sumup all the matrices coming into reducer.

So I need to first parse my string and I stored them into 2 double array. I am geting all the ke matrix and val matrix in reducer.

But I am not able to sumup.

Any suggestion.

Inorder to get the sum outside the forloop,i declared them as static.

public class Reducer  extends Reducer<IntWritable, MW, Text, Text> {       static double[][] key;     static double[][] value;     public void reduce(IntWritable  keys,             Iterable<MW> values, Context context)             throws IOException, InterruptedException {      for (MW c : values)     {         String data = c.toString();         data = data.trim();         String[] parts = data.split("#");             String part1 = parts[0];             String part2 = parts[1];         /*          * Parse key          */         String[] keyrows = part1.split(",");          String[][] keymatrix = new String[keyrows.length][];          int keyr = 0;         for (String keyrow : keyrows) {             keymatrix[keyr++] = keyrow.split("\|");         }          double[][] ke = new double[keymatrix.length][keymatrix[0].length];        for (int i = 0; i<keymatrix.length; i++) {            for (int j = 0; j<keymatrix[0].length; j++) {                ke[i][j] = Double.valueOf(keymatrix[i][j]);         }        }       key = new double[ke.length][ke[0].length];         for(int sumi = 0;sumi<ke.length;sumi++){            for(int sumj=0;sumj<ke[0].length;sumj++){                key[sumi][sumj] += ke[sumi][sumj];            }        }     /*Parsing  value     */           String[] valuerows = part2.split(",");          String[][] valuematrix = new String[valuerows.length][];          int valr = 0;         for (String valuerow : valuerows) {             valuematrix[valr++] = valuerow.split("\|");         }          double[][] val = new double[valuematrix.length][valuematrix[0].length];        for (int i = 0; i<valuematrix.length; i++) {            for (int j = 0; j<valuematrix[0].length; j++) {        val[i][j] = Double.valueOf(valuematrix[i][j]);         }         }           //calculating sum for value         value = new double[val.length][val[0].length];         for(int sumi = 0;sumi<val.length;sumi++){            for(int sumj=0;sumj<val[0].length;sumj++){                value[sumi][sumj] += val[sumi][sumj];            }        }                    }   System.out.println("sum 1");         for(int diai=0;diai<key.length;diai++){             for(int diaj=0;diaj<key[0].length;diaj++){                 System.out.print(key[diai][diaj]+"	");              }             System.out.println("");          }     System.out.println("sum 2");         for(int diai=0;diai<value.length;diai++){             for(int diaj=0;diaj<value[0].length;diaj++){                 System.out.print(value[diai][diaj]+"	");              }             System.out.println("");          } 

UPDATE I think the problem is with in line

 key = new double[ke.length][ke[0].length]; 

and

value = new double[val.length][val[0].length]; 

before summing I am rebuilding the matrix key and value inside the loop.

It should build it once before the loop and then add to it. But to do that I should do

double[][] key = new double[ke.length][ke[0].length]; double[][] value = new double[val.length][val[0].length]; 

before

for (MW c : values)     { 

but How will I get the dimensions outside the for loop?