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Maintain Order using TreeMap wrapped in HashMap.  Need urgent help!!

Posted on 2004-09-20
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Last Modified: 2010-08-05
Hi All,
I have the following question:
I store data in HashMap, but I need that the data displayed in certain order on my JSP.  I've created a method that sorts my unsorted HashMap, puts the data into TreeMap and then TreeMap is copied to the HashMap.  When I call this method from my JSP it seems that the order is not always retained.  Could you help me to understand why it happens?  Please see the method below..
Thanks!!!


public HashMap sortAllForDisplay(HashMap unsortedData){
            HashMap sortedData = new HashMap();
            ArrayList workAssignOrders = new ArrayList();
            HashMap workAssignLookUp = new HashMap();
      
            JobAccess jbAccess = new JobAccess(this.getDBConnection());
            List l = jbAccess.loadAll();
            if (l!=null && l.size()>0)
            {
                  for (int i=0;i<l.size();i++)
                  {
                        JobData jbData = (JobData)l.get(i);
                        String jobName = jbData.getJobName();
                        int jobId = jbData.getJobId();
                        String jobOrderNumber = jbData.getJobVal2(); //Work Assignment Order
      
                        if (jobOrderNumber==null)
                        {
                              jobOrderNumber = "99999";
                        }
                        
                        Integer jobOrderNumberInt = new Integer(Integer.parseInt(jobOrderNumber));

                        if (!workAssignOrders.contains(jobOrderNumberInt)){
                              workAssignOrders.add(jobOrderNumberInt);
                        }
                        workAssignLookUp.put(new Integer(jobId), jobOrderNumberInt);
                  }
                  
                  
                  if(workAssignOrders!=null)
                  {
                        Collections.sort(workAssignOrders); // Sort Orders in ascending order
                        Collections.reverse(workAssignOrders);
                        
                  
                                    if (workAssignOrders.size()>0)
                                    {
                                          TreeMap tempMap = new  TreeMap();
                                          int realKey = 0;
                                          for (int x=0;x<workAssignOrders.size();x++)
                                          {
                                                                        
                                                            Integer order = (Integer)workAssignOrders.get(x);
                                                            Collection col = unsortedData.values();                                                                                    
                                                            Iterator it = col.iterator();
                                                                  
                                                                  //int keyCounterInner = 1;
                                                                              while (it.hasNext())
                                                                              {
                                                                                    
                                                                                    ArrayList rowData = (ArrayList)it.next();
                                                                                    Integer dataLaborId = (Integer)rowData.get(0);
                                                                                    Integer compareJobOrder = (Integer)workAssignLookUp.get(dataLaborId);
                                                                                    

                                                                                    if (order.compareTo(compareJobOrder)==0)
                                                                                    
                                                                                    {
                                                                        
                                                                                          tempMap.put(new Integer(realKey), rowData);
                                                                                          
                                                                                          realKey ++;
                                                                                          
                                                                                          //
                                                                                    }
                                                                                    
                                                                                    
                                                                              }
                                                      
                                                            
                                                }
                                                
                                                      sortedData.putAll(tempMap);
                                          
                                                
                                          
                                    }
                                    
                                    else
                                    {
                                          sortedData = unsortedData;
                                    }
                  }                  
                  
            }
            
            else
            {
                  sortedData = unsortedData;
            }
            return sortedData;
      }
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Question by:germess
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3 Comments
 
LVL 6

Expert Comment

by:expertmb
ID: 12109331
HashMap
From API doc
This class makes no guarantees as to the order of the map; in particular, it does not guarantee that the order will remain constant over time.
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Author Comment

by:germess
ID: 12109394
thanks for your response,
Understood! I've read it in the API.. but how can we ensure the order? Should we pass the TreeMap to the JSP? Or sort the hashMap on the JSP? Please let me know your thoughts..
i appreciate your help!
germess
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Accepted Solution

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expertmb earned 500 total points
ID: 12109409
>>Should we pass the TreeMap to the JSP?
hmmm thts the best option. its a map with sorted order. i think no need to convert from treemap to hashmap again.
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