code: public void initializeLayerTable() {
          layerTable = new Vector();
          layerNames = new Vector();
          for( int i = 0; i < dwgObjects.size(); i++ ) {
              DwgObject obj = (DwgObject) dwgObjects.get(i);
              if (obj instanceof DwgLayer) {
                  Vector layerTableRecord = new Vector();
                  layerTableRecord.add(new Integer(obj.getHandle()));
                  layerTableRecord.add(((DwgLayer) obj).getName());
                  layerTableRecord.add(new Integer(((DwgLayer) obj).getColor()));
                  layerTable.add(layerTableRecord);
                  layerNames.add(((DwgLayer) obj).getName());
              }
          }
          System.out.println("");
      }
docs: Initialize a new Vector that contains the DWG file layers. Each layer have three
  parameters. These parameters are handle, name and color