如何比较arraylist与列表 <string[]> java的

Question

    List<String[]> sarray;
    ArrayList<ContentTable> currentData=new ArrayList<ContentTable>();

    //here sarray is initialized with data
    sarray = reader.readAll();


    for(String[] arr : sarray) 
        {
          System.out.println("array data "+ Arrays.toString(arr));
        }

        for(ContentTable ct : currentData)
        {
            System.out.println("list data "+ct.getId() +" "+ ct.getSubid() +" "+ct.getChpid()+" "+ct.getSec_name()+" "+ct.getContent());
        }   

Output for 1 result of array and list :

array data -> [9, 10, 83, Concepts: 1-10, <p>We&#x2019;ll discuss many of the concepts in this chapter in depth later. But for now, we need a brief review of these concepts to equip you for solving exercises in the chapters that follow.</p>] [9, 10, 83, Concepts: 1-10, <p>We&#x2019;ll discuss many of the concepts in this chapter in depth later. But for now, we need a brief review of these concepts to equip you for solving exercises in the chapters that follow.</p>]

list data -> 9 10 83 Concepts: 1-10 <p>We&#x2019;ll discuss many of the concepts in this chapter in depth later. But for now, we need a brief review of these concepts to equip you for solving exercises in the chapters that follow.</p> 9 10 83 Concepts: 1-10 <p>We&#x2019;ll discuss many of the concepts in this chapter in depth later. But for now, we need a brief review of these concepts to equip you for solving exercises in the chapters that follow.</p>

 //fields with getters and setters in ContentTable Class
        public class ContentTable {

            int id;
            int subid;
            int chpid;
            String sec_name;
            String content;
          }

Now what I want to achieve is to create two lists ,

ArrayList<ContentTable> updatedData=new ArrayList<ContentTable>();
ArrayList<ContentTable> addedData=new ArrayList<ContentTable>();

these would be filled with data after comparison of sarray and currentdata in such a way that,

if ct.getSec_name() or ct.getContent() at a particular index in currentdata is not equal to the data present in sarray then it would be added to updatedData

And,

if ct.getId() , ct.getSubid() , ct.getChpid() at a particular index is not equal to any of sarray data then it would be added to addedData

What would be the elegant way to do this with lesser complexity and I want to do it fastest as it might take time to compare each element in Arraylist currentData to compare with each element in ArrayList sarray .

Answer 1

How about wrapping each element in array to Content. Now adding these content objects to Set. Iterate over the ArrayList and for each element in array list, check if its present in the set. If not update the addedData. If yes, get that object and compare both the content objects using equals.

Note that you would anyway override the hashCode and equals in Content type to make this(Set) work.

The one time activity that you do in the beginning will take time, which is getting the set ready. But once this set is ready, look ups with be really fast.

Answer 2

So, a better solution for my problem was to not compare a List<String[]> to ArrayList , but to convert List<String[]> to another Arraylist and then compare the new Arraylist against the older one. And that's quite simple and easier approach , I found.

                for(String[] arr : sarray) 
                {
                  ContentTable data=new ContentTable();

                  for(String s : arr)   
                  {
                         data.setId(Integer.parseInt(s));
                         data.setSubid(Integer.parseInt(s));
                         data.setChpid(Integer.parseInt(s));
                         data.setSec_name(s);
                         data.setContent(s);
                  }
                  newData.add(data);
                }

Now, newData is having the fresh data that I want to compare against currentData.