Hello everybody!
So, I just tried to create a ArrayList of ArrayLists with a custom class.
However I am a bit stuck on how to read from / write to certain elements in this ArrayList thing.
`
class Event
{
//The class for each element in the array
//Just some example variables for now ...
int ExampleInt;
String ExampleString;
}
Event DefaultEvent;
//An EventString is a collection of Events
ArrayList EventString = new ArrayList();
//The EventTable is a collection of EventStrings
ArrayList EventTable = new ArrayList ();
void PrintEventData (int EventString, int EventID)
{
//Prints event data
//“Copy” the specified element into a temporary variable for easier printing
Event EventToPrint;
EventToPrint = EventTable.get(EventString).get(EventID);
```
print("Example Int = ");
print(EvenToPrint.ExampleInt);
print("Example String = ");
print(EvenToPrint.ExampleString);
print("\n");
```
`
`}
`
This is the error that the compiler gives me:
Cannot convert from Object to EventSimulator.Event
I am pretty sure that this is about the following line:
EventToPrint = EventTable.get(EventString).get(EventID);
But this does make no sense!
The type of what the EventTable.get(EventString).get(EventID) returns is Event, right? And the type of EventToPrint is Event, so why is this not working?
How can I get this to work?
---
array list of array lists of vectors:
`ArrayList> name = new ArrayList>();`
how to use it?
use
```auto
ArrayList> points = new ArrayList>();
ArrayList group = new ArrayList();
loadPoints(); //a custom function (name it anything) to add random points to group() ArrayList.
points.add(group);
//how to access information of points > group
//(what used to be the group ArrayList, which is inside of the ArrayList.
points.get( ). get();
//if you don't know, ArrayList) acts exactly the same as a PVector. similary,
//ArrayList>.get() acts the same as ArrayList. Therefor, you can do
//points.get().get();
```
---
that’s right.
As stated in the reference you have to either cast the type from Object to your class OR as has been shown, tell the ArrayList it’s type using `ArrayList`
---
> [@ProgrammingN00b](#):
>
> The type of what the EventTable.get(EventString).get(EventID) returns is Event, right? And the type of EventToPrint is Event, so why is this not working?
When creating an ArrayList without specifying the type that it’s going to hold, it’s the same as saying :
```auto
ArrayList