Question

This for loop should sum all values contained in the treemap. This works, but after the inner loop the values up and down are used to calculate the accuracy. It seems that this is never executed.

What am I doing wrong?

            // for each row
        for (Entry<String, TreeMap<String, Integer>> table_row : table.entrySet()) {

            // write the label
            String row = table_row.getKey() + ",";

            int up = 0;
            int down = 0;
            float accu = 0;
                    // for each treemap in the row
            for (Entry<String, Integer> collumn : table_row.getValue().entrySet()) {
                row += collumn.getValue() + ",";
                down += collumn.getValue();//this works
                if (collumn.getKey() == table_row.getKey()) {
                    up = collumn.getValue();
                    }
            }

    --------->  accu = (up / down) * 100; //this is not executed?? 
            System.out.println("t: " + up + " n: " + down + " a: " +  accu);
            row = row + Float.toString(accu) + " %";
            writer.println(row);//this works too but output is always 0%
        }

Answer 1

Integer division!

Your down value is larger than your up and rounding down to zero, so each time you assign accu, you are effectively doing this accu = (0) * 100

If you are looking for precision, you should make up and down floats instead of ints, or make a cast right before you divide.