code: private void processPredecessors(Gantt gantt)
     {
        for (Gantt.Tasks.Task ganttTask : gantt.getTasks().getTask())
        {
           String predecessors = ganttTask.getP();
           if (predecessors != null && !predecessors.isEmpty())
           {
              String wbs = ganttTask.getID();
              Task task = m_taskMap.get(wbs);
              for (String predecessor : predecessors.split(";"))
              {
                 Task predecessorTask = m_projectFile.getTaskByID(Integer.valueOf(predecessor));
                 task.addPredecessor(predecessorTask, RelationType.FINISH_START, ganttTask.getL());
              }
           }
        }
     }
docs: Read predecessors from a Gantt Designer file.
  
  @param gantt Gantt Designer file