Add a List<object> or Arraylist to an array of CustomObject[]

Question

I have tried many ways like Cast<CustomObject>, as Customobject and ToArray(Customobject) but nothing worked.

How can I add List or ArrayList via AddRange to a CustomObject[] Array?

Code is really difficult. But if you have some time you can get the complete source of the destination list from here: http://www.codeproject.com/Articles/4012/C-List-View-v1-3?msg=3844172#xx3844172xx

This is a Custom Listview I activated a combobox for the second column, so I can select diferrent values for a cell. But before this, I have to add something to select. This is the hole problem.

Update: Firstly, thanks for the help ! Secondly, Found a solution in the comments from the website with the source. Had to add some code and changed the destination custom array to a List

Are the objects in your List<object> instances of CustomObject? Because if they aren't, you can't do it. — Brian Warshaw
– Brian Warshaw, Commented Sep 13, 2012 at 12:30
Try breaking down the problem. What's the very bit of code where you add the items to the combo box? Breaking it down to a little piece of code may help you too. — Matthias Meid
– Matthias Meid, Commented Sep 13, 2012 at 14:22

verdesmarald · Accepted Answer · 2012-09-13 12:33:17Z

6

list.Cast<CustomObject>().ToArray()

Will work as long as the things in the list are actually CustomObject. If they might be other types, you can use OfType<CustomObject>() instead of Cast. This will filter out anything of an incompatible type.

answered Sep 13, 2012 at 12:33

verdesmarald

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5 Comments

verdesmarald Over a year ago

@Rene You are welcome. If this solved your problem, please click the check mark next to the answer to mark it as accepted.

Rene Over a year ago

In 4 minutes... (Wait time from tackoverflow)

Rene Over a year ago

Too fast, its not working... Says cannot convert string to GLSubItem, but if I only add one item (.Add("myString")) it works...

Matthias Meid Over a year ago

@Rene You should really show us some code to see what is wrong.

verdesmarald Over a year ago

@Rene Sorry to hear that, but it is difficult to offer any suggestions based on the current question. If you update it to include some example code that reproduces your problem, that will make it easier.

Rotem · Accepted Answer · 2012-09-13 12:32:39Z

1

Assuming the objects really are instances of CustomObject, use LINQ Select method:

objList.Select(o => o as CustomObject).ToArray();

Otherwise you will get an array of null.

answered Sep 13, 2012 at 12:32

Rotem

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Nikhil Agrawal · Accepted Answer · 2012-09-13 12:33:08Z

0

If its a List<CustomObject> then let us say

CustomObject[] coarr = list_of_customobject.ToArray();

If its an ArrayList then

CustomObject[] coarr = arraylist.OfType<CustomObject>().ToArray();

answered Sep 13, 2012 at 12:33

Nikhil Agrawal

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Spontifixus · Accepted Answer · 2012-09-13 12:34:53Z

0

If you are unsure whether all of your objects are of the type CustomObject try

var result = list.OfType<CustomObject>.ToArray();

answered Sep 13, 2012 at 12:34

Spontifixus

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Matthias Meid · Accepted Answer · 2012-09-13 12:54:37Z

Strictly speaking you cannot add elements to an array, since an array's length remains constant over its lifetime. There are two things you can do:

Create a new array

myArray = myTList.ToArray() // generic)
myArray = myArrayList.Cast<CustomObject>().ToArray() // cast, non-generic
myArray = myArrayList.OfType<CustomObject>().ToArray() // filter by type, non-generic

Set elements of an array

myArray[x] = myTList[y] // generic
myArray[x] = (CustomObject)myArrayList[y] // non-generic

I recommend you to take the generic collection whenever possible. They provide you additional type safety. Casting object variables cause runtime errors you could detect at compile time by using generic types.

If you actually want to add elements to an existing collection, you may try to use a dynamic collection type rather than an array: List<T> : IList<T> or LinkedList<T> : ICollection<T> are a good point to start, or maybe more specific types like Stack<T> or Queue<T>.

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