Empty value in write() method : Custom Datatype in Hadoop MapReduce

问题

I am emitting two 2D double arrays as key and value. I am constructing WritableComparable class.

public class MF implements WritableComparable<MF>{

/**
 * @param args
 */
private double[][] value;

public MF() {
    // TODO Auto-generated constructor stub
}

public MF(double[][] value) {
    // TODO Auto-generated constructor stub

      this.value = new double[value.length][value[0].length];
    // System.out.println("in matrix");
}

public void set(double[][] value) {
      this.value = value;
}

public double[][] getValue() {
        return value;
}

@Override
public void write(DataOutput out) throws IOException {
    System.out.println("write");
    int row=0;
    int column=0;
    for(int i=0; i<value.length;i++) {
        row = value.length;
        for(int j=0; j<value[i].length; j++) {
            column = value[i].length;
        }
    }
    out.writeInt(row);
    out.writeInt(column);

    for(int i=0;i<row ; i++) {
        for(int j= 0 ; j< col;j++) {
            out.writeDouble(value[i][j]);
        }
    }

    for(int i =0;i< value.length ;i ++) {
        for(int j = 0;j <value[0].length;j++) {
            System.out.print(value[i][j]+ "\t");
        }
        System.out.println("");
    }
}

@Override
public void readFields(DataInput in) throws IOException {
    int row = in.readInt();
    int col = in.readInt();

    double[][] value = new double[row][col];
    for(int i=0;i<row ; i++) {
        for(int j= 0 ; j< col;j++) {
            value[i][j] = in.readDouble();
        }
    }
}

@Override
public int hashCode() {

}

@Override
public boolean equals(Object o) {

}

@Override
public int compareTo(MF o) {
    // TODO Auto-generated method stub
    return 0;
}

@Override
public String toString() {
    System.out.println(Arrays.toString(value));
    return Arrays.toString(value);
}
}

And half way through, when I tried to print my matrix within write method, the matrix is not having values

write
    0.0 0.0 0.0 
    0.0 0.0 0.0 
    0.0 0.0 0.0 
write
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 
    0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

I am doing something wrong. I am getting apt no of rows and cols.

来源：https://stackoverflow.com/questions/19674314/empty-value-in-write-method-custom-datatype-in-hadoop-mapreduce

标签

java

Hadoop

writable