Lists in Dynamics 365 for Operation

There are 4 different data structures/collection classes/ that can be used when developing in D365.

  • Lists
  • Maps
  • Sets
  • Arrays
  • Structs

Most of these can be familiar from other languages. I will highlight the main points for these data structures, as well as provide examples of their usage. These data structures can be used to store any data types including objects.

List

List sequentially holds elements assigned to it. All values in the list must be of the same type.

Initiate

To initiate the list you have to write following piece of code where instead of Types::Integer, you can use any type including objects.

List             list  = new List(Types::Integer);

Add values

To add values to already initialized list you can use one of the following functions.

list.addEnd(25);
list.addStart(3);

Function addEnd ends a value in the end of the list. Alternatively, function addStart inserts new value in the beginning of the list.

Read values

To output all values from the list you can use following function.

list.toString();

if you want to get a specific value from the list, then you will have to use following code.

ListIterator     iterator;
enumerator = list.getEnumerator();
enumerator.reset();
enumerator.moveNext()
int i = enumerator.current();

ListEnumerator is the class that helps to iterate through list, by accessing each element of the list individually. To get a value of the list we are using function current()

Example

    public static void main(Args _args)
    {    

        List                list  = new List(Types::Integer);
        ListEnumerator      enumerator;

        list.addEnd(1);
        list.addEnd(21);
        list.addEnd(22);
        list.addEnd(23);
        list.addEnd(24);
        list.addEnd(25);
        list.addStart(3);

        info( list.toString());

        enumerator = list.getEnumerator();
        enumerator.reset();
        while(enumerator.moveNext())
        {
            info(int2str(enumerator.current()));
        }     
    }

 

Line by line with visual explanation:

This line of code executes the initialization of the list.

List                list  = new List(Types::Integer);

14

description of the variable fro listEnumerator, that will help to get values from the list

ListEnumerator      enumerator;

15

Adding the first element with value 1 to the list from the end

list.addEnd(1);

3

Adding the second element with value 21 to the list from the end

list.addEnd(21);

4

Adding the third element with value 22 to the list from the end

list.addEnd(22);

5

Adding the fourth element with value 23 to the list from the end

list.addEnd(23);

6

Adding the fifth element with value 24 to the list from the end

list.addEnd(24);

7

Adding the sixth element with value 25 to the list from the end

list.addEnd(25);

8

Adding the seventh element with value 3 to the list from the beginning. If we were to start reading our list, the first element we will get will be the element with value 3

list.addStart(3);

9

Initialization of the enumerator. Now enumerator is attached to the list. On the image below you may notice that enumerator looks like an arrow, and this arrow doesn’t point at any particular element.

enumerator = list.getEnumerator();

10

Because of that we have to reset the enumerators value to make sure that we will be pointing at the beginning of our list. After we use the function reset, the list enumerator “points” at the beginning of the list, not at the first element!

enumerator.reset();

11

To move enumerator to the first element, you have to executed move next method. After that you can work with list elements. You can get the value of the list by using method current();

enumerator.moveNext())

12

to move to the next element you can use the same operation. Notice you cannot move back, only move forward. If you need to start over,  you can use reset();

 

enumerator.moveNext())

13

 

You can notice that there is no description of how to remove the value from the list. To do that you can use class listIterator method delete. As you may suggest , you have to be careful when using it, if you insert/ delete something from the list using iterator, when you have initialized enumerator, you will not be able to use enumerator without invoking error.

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