gistfile1.java

  /* Component */

  interface PolyColumn {
    public void writeToInput(Map<String, String> inputCsvColumns, BondEx bond);
  }

  /* Composite */

  class CompositePolyColumn implements PolyColumn {

    private List<PolyColumn> childPolyColumns = new ArrayList<PolyColumn>();

    public void add(PolyColumn polyColumn) {
      childPolyColumns.add(polyColumn);
    }

    public void remove(PolyColumn polyColumn) {
      childPolyColumns.remove(polyColumn);
    }

    public void writeToInput(Map<String, String> inputCsvColumns, BondEx bond) {
      for (PolyColumn polyColumn : childPolyColumns) {
        polyColumn.writeToInput(inputCsvColumns, bond);
      }
    }
  }

  /* Leaf */

  class Oas implements PolyColumn {
    public void writeToInput(Map<String, String> inputCsvColumns, BondEx bond) {
      inputCsvColumns.put(Ply.OAS.getLabel(), Ply.OAS.getDefaultValue());
    }
  }

  /* Some other Leaf */

  class Price implements PolyColumn {
    public void writeToInput(Map<String, String> inputCsvColumns, BondEx bond) {
      inputCsvColumns.put(Ply.PRICE.getLabel(), bond.getOfferPrice());
    }
  }

  /* Client */

  public class Client {
    public static void main(String[] args) {
      PolyColumn oas = new Oas();
      PolyColumn price = new Price();

      CompositePolyColumn compositePolyColumn = new CompositePolyColumn();
      compositePolyColumn.add(oas);
      compositePolyColumn.add(price);

      compositePolyColumn.writeToInput(new HashMap<String, String>);
    }
  }


  /* Helper enum */

  public enum Ply {
    OAS("OAS", ""),
    PRICE("Price", "30");

    private String label;
    private String defaultValue;

    Ply(String label, String defaultValue) {
      this.label = label;
      this.defaultValue = defaultValue;
    }

    public String getLabel() {
      return label;
    }

    public String getDefaultValue() {
      return defaultValue;
    }
  }