Greater Than or equal into String Variables

public Component prepareRenderer(TableCellRenderer renderer, int row, int column)
{
    Component c = super.prepareRenderer(renderer, row, column);

    c.setBackground(getBackground());
    int modelRow = convertRowIndexToModel(row);
    String Value = (String)getModel().getValueAt(modelRow, 7);
    if (Value <= 30) c.setBackground(Color.GREEN);
    return c;
}

This is my codes. In the if Statement I want to compare it if its greater than or equal to 30.