Accessing Objects from a 2d Arraylist of Custom Objects in Java

Question

Consider the following case. I have 2 classes as shown below:

public class CustomObject{

  public int a;
  public String xyz;
  public ArrayList<Integer> arrInt;
  public SomeOtherClass objectSOC;

   public CustomObject(){
   //Constructor
        }
  /*Followed by other methods in the class*/

  }

Now there is another class in which I have created ArrayList[][] of CustomObject, the way shown below

public class CustomObjectUtil{

 ArrayList<CustomObject>[][] arrCO = new ArrayList[100][100];

 public CustomObjectUtil(){
 //Assume there is an object of CustomObject class, let's call it ObjectCO, and a method that adds values to the arrCO using arrCO[i][j].add(ObjectCO);

 //Now, here I want to access objects from my 2D ArrayList as
   String stringCO = arrCO[indx][indy].xyz;
   ArrayList<Integer> arrIntCO = arrCO[indx][indy].arrInt;
   SomeOtherClass objectSOC_CO = arrCO[indx][indy].objectSOC;
 // But the above method is not allowed;
      }

 }

I could not find a way to do this type of assignment. Please comment if you need more info!

@ANS It's a multidimensional array of ArrayList. It compiles. — Vince
– Vince, Commented Apr 11, 2017 at 10:50
@VinceEmigh It does not compile fine. It compiles with warnings. — Tom Hawtin - tackline
– Tom Hawtin - tackline, Commented Apr 11, 2017 at 16:14
@TomHawtin-tackline I didn't say fine, I just said it compiles, as in "the grammar allows it". — Vince
– Vince, Commented Apr 11, 2017 at 18:53

RajatJ · Accepted Answer · 2017-04-11 11:28:53Z

1

Object referenced by arrCO[indx][indy] is an ArrayList

arrCO is a 2-D array of List of CustomObject

do this to access what you're trying to access:

List<CustomObject> customObjList = arrCO[indx][indy];
CustomObject customObj = customObjList.get(0)  // assuming there are elements in this list

Now you can access arrInt & objectSOC as

customObj.arrInt & customObj.objectSOC

edited Apr 11, 2017 at 11:28

answered Apr 11, 2017 at 11:17

RajatJ

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1 Comment

Devendra Vyas Over a year ago

Thanks a lot! I was interpreting the declaration itself in a faulty manner. Just to add to it a bit, if anyone wants to further visualise it a bit in their head, viewing variable in Debugger mode in any IDE, NetBeans/Eclipse might help!

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