Efficiency Deficiency

CODU MEU:

public class DoubleDataFrame implements DataFrame<Double>
{
	private double[][] data;
	private List<String> columnNames;
	private Map<String,Integer> nameIndices = new HashMap<>();

	public DoubleDataFrame(List<String> columnNames, double [][] data) {
		this.data = data;
		this.columnNames = new ArrayList<>(columnNames);
		int i=0;
		for(String name : columnNames) {
			nameIndices.put(name, i);
			i++;
		}
	}

	@Override
	public int getRowCount() {

		return this.data.length;
	}

	@Override
	public int getColumnCount() {

		return this.getColumnNames().size();
	}

	@Override
	public List<String> getColumnNames() {
		List<String> immutableColumnNames = Collections.unmodifiableList(this.columnNames);
		return immutableColumnNames;
	}

	@Override
	public void setValue(int rowIndex, String colName, Double value)
			throws IndexOutOfBoundsException, IllegalArgumentException {
		if (rowIndex<0 || rowIndex>this.getRowCount()) {
			throw new IndexOutOfBoundsException("Invalid row index provided.");
		}
		if (!this.getColumnNames().contains(colName)) {
			throw new IllegalArgumentException("Non-existing column name.");
		}
		this.data[rowIndex][nameIndices.get(colName)] = value;

	}

	@Override
	public Double getValue(int rowIndex, String colName) throws IndexOutOfBoundsException, IllegalArgumentException {
		if (rowIndex<0 || rowIndex>this.getRowCount()) {
			throw new IndexOutOfBoundsException("Invalid row index provided.");
		}
		if (!this.getColumnNames().contains(colName)) {
			throw new IllegalArgumentException("Non-existing column name.");
		}
		return data[rowIndex][nameIndices.get(colName)];
	}

TESTERU:

int size = 10000;
		double [][] data = new double [1][ size ];
		List < String > header = new ArrayList < >( size ) ;
		for (int j =0; j < size ; j ++)
		{
		data [0][ j ] = j ;
		header . add ("x_"+ j ) ;
		}
		DoubleDataFrame df = new DoubleDataFrame ( header , data ) ;
		 long time = System . currentTimeMillis () ;
		 for (int j =0; j < size ; j ++)
		 {
		 df . getValue (0 , header . get ( j ) ) ;
		 df . setValue (0 , header . get ( j ) , 0d ) ;
		 }
		 time = System . currentTimeMillis () - time ;
		 System . out . println (" Running time : "+ time +"ms") ;