Java: JTable Anzeigewert runden, eig. Wert aber nicht runden

import java.text.NumberFormat;

import javax.swing.table.AbstractTableModel;

public class DoubleModel extends AbstractTableModel {

    private static final long  serialVersionUID = 8564625022160734884L;

    private final double[][]   data;

    private final NumberFormat formater;

    private final int          rows;

    private final int          cols;

    public DoubleModel(int rows, int cols) {

        this.rows = rows;

        this.cols = cols;

        data = new double[rows][cols];

        formater = NumberFormat.getInstance();

        formater.setMaximumIntegerDigits(2);

    }

    @Override

    public int getColumnCount() {

        return cols;

    }

    @Override

    public int getRowCount() {

        return rows;

    }

    @Override

    public Object getValueAt(int rowIndex, int colIndex) {

        return formater.format(data[rowIndex][colIndex]);

    }

    public double getData(int rowIndex, int colIndex) {

        return data[rowIndex][colIndex];

    }

    public void setData(int rowIndex, int colIndex, double newVal) {

        data[rowIndex][colIndex] = newVal;

        fireTableCellUpdated(rowIndex, colIndex);

    }

}