Java – Categorizes different types of objects into a list

I

have the following issue and I’m not quite sure how to fix it. I request data from several different servers, each returning a list of objects of different types (each with its own specific unique POJO object type) – but what all of these object lists have in common is that all objects have a date parameter. Then I need to display all the objects in the list as a huge mixed list for the user to use, all sorts of various objects sorted by date.

I

made an adapter that extends the baseadapter, and I’ve passed all the object array lists to that adapter – but how can I sort all these object lists by date and show them all together? I could create a “super object” with properties from all the other objects and then create a sorted array for this super object to pass to the adapter, but that seems like a confusing and rough solution. Is there a more elegant way to do this?

public class someAdapter extends BaseAdapter
{
...

public someAdapter(ArrayList<ObjectOne> objectOneArray, ArrayList<ObjectTwo> objectTwoArray) {
        if (objectOneArray != null) {
            this.localObjectOneList.addAll(objectOneArray);
        }
        ...
}
}

Object type example:

public class ObjectOne implements Serializable {
private String date;
private String someFieldOne;
private String someFieldTwo;

...
getters and setters
...
}

To reiterate – the final list must be a combination of all the different object types in date order.

Without a large pipeline associated with it, the way you initially expected to have a superclass would be fine.
A better approach is to assume that all POJOs have a getDate() method.

1. Declare a method getDate() to retrieve the date object from any POJO.
2. Declare Comparator comparison dates

3. Sort the objects

   If the POJO does not have a getter, i.e. the getDate() method, replace getDateFromMethod() with getDateFromProperty() in the comparator

   public class Sorter{ public void sortList()
   {
       Collections.sort(objList, comparator);
   
    Now consume / print your objList to get sorted by date
   }
   
   ArrayList<Object>   objList     = new ArrayList<Object>();
   
   Comparator<Object>  comparator  = new Comparator<Object>()
                                   {
   
   @Override
                                   public int compare(Object object1, Object o2)
                                       {
                                           Date o1Date = getDateFromMethod(object1);
                                           Date o2Date = getDateFromMethod(o2);
                                           if (o1Date != null && o2Date != null)
                                           {
                                               if (o1Date.before(o2Date))
                                                   return -1;
                                               else if (o1Date.after(o2Date))
                                                   return 1;
   
   else
                                                   return 0;
                                           }
                                           else
                                               return -1;
                                       }
                                   };
   
   public Date getDateFromMethod(Object obj)
   {
   
   Date date = null;
       String getDate = "getDate";
       try
       {
           Method method = obj.getClass().getMethod(getDate, (Class<?>[]) null);
           if (method != null)
               date = (Date) method.invoke(obj, (Object[]) null);
       }
       catch (NoSuchMethodException e)
       {
            TODO Auto-generated catch block
           e.printStackTrace();
       }
       catch (SecurityException e)
       {
            TODO Auto-generated catch block
           e.printStackTrace();
       }
       catch (IllegalAccessException e)
       {
            TODO Auto-generated catch block
           e.printStackTrace();
       }
       catch (IllegalArgumentException e)
       {
            TODO Auto-generated catch block
           e.printStackTrace();
       }
       catch (InvocationTargetException e)
       {
            TODO Auto-generated catch block
           e.printStackTrace();
       }
   
   return date;
   }public Date getDateFromProperty(Object obj)
                               {
                                   Date date=null;
                                   try
                                   {
                                   Field dateField=    obj.getClass().getField("date");
                                   if(dateField!=null)
                                       date=(Date) dateField.get(obj);
                                   }
                                   catch (NoSuchFieldException e)
                                   {
                                        TODO Auto-generated catch block
                                       e.printStackTrace();
                                   }
                                   catch (SecurityException e)
                                   {
                                        TODO Auto-generated catch block
                                       e.printStackTrace();
                                   }
                                   catch (IllegalArgumentException e)
                                   {
                                        TODO Auto-generated catch block
                                       e.printStackTrace();
                                   }
                                   catch (IllegalAccessException e)
                                   {
                                        TODO Auto-generated catch block
                                       e.printStackTrace();
                                   }
   
   return date;
   
   }
   

   Now suppose you have the following Obj1, Obj2, and Obj3, use these POJOS to create objects and populate objList and test the solution.

Class obj1
{
Build number;
integer name;
Date date;

public Date getDate()

{
Return date;
}
Public int getId()
{
Returns the ID;

public void setId(int id)
{
    this.id = id;
}

public int getName()
{
    return name;
}

public void setName(int name)
{
    this.name = name;
}

Class obj2
{
integer sequence;
internal location;
Date date;

public Date getDate()

{
Return date;
}
public int getSequence()
{
return sequence;

public void setSequence(int sequence)
{
    this.sequence = sequence;
}

public int getLocation()
{
    return location;
}

public void setLocation(int location)
{
    this.location = location;
}

Class Obj3
{
integer type;
internal sources;
Date date;

public Date getDate()

{
Return date;

public void setDate
{
this.date = date;

public int getType()
{
    return type;
}

public void setType(int type)
{
    this.type = type;
}

public int getOrigin()
{
    return origin;
}

public void setOrigin(int origin)
{
    this.origin = origin;
}