Is there a way to get the type of object in the arraylist?
I need to make an IF statment as the following (in C#):
if(object is int)
//code
else
//code
thanks
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4 Answers
you can use the normal GetType() and typeof()
if( obj.GetType() == typeof(int) )
{
// int
}
Comments
What you are doing is fine:
static void Main(string[] args) {
ArrayList list = new ArrayList();
list.Add(1);
list.Add("one");
foreach (object obj in list) {
if (obj is int) {
Console.WriteLine((int)obj);
} else {
Console.WriteLine("not an int");
}
}
}
If you were checking for a reference type instead of a value type, you could use the as operator, so that you would not need to check the type first and then cast:
foreach (object obj in list) {
string str = obj as string;
if (str != null) {
Console.WriteLine(str);
} else {
Console.WriteLine("not a string");
}
}
Comments
Use GetType() to know the type of Object.
Comments
That's pretty much how you do it:
if (theArrayList[index] is int) {
// unbox the integer
int x = (int)theArrayList[index];
} else {
// something else
}
You can get a Type object for the object, but then you should make sure that it's not a null reference first:
if (theArrayList[index] == null) {
// null reference
} else {
switch (theArrayList[index].GetType().Name) {
case "Int32":
int x = (int)theArrayList[index];
break;
case "Byte":
byte y = (byte)theArrayList[index];
break;
}
}
Note that unless you are stuck with framework 1.x, you shouldn't use the ArrayList class at all. Use the List<T> class instead, where you should use a more specific class than Object if possible.
2 Comments
Andrew Bezzub
It would be better to extract value from the list using indexer only once and then cast it to the necessary type.
Guffa
@Andrew: Yes, that is correct. I wrote the example to demonstrate the type recognition and casting, it's not optimal in other aspects.
