Question: Now, before you start clicking the down arrow on this question, hear me out.

I am doing a paper on Dynamic Arrays in my Java class. I already know the normal Arrays (1D and 2D) and the ArrayList. Now, My teacher claims there are more kinds of dynamic arrays, but she refuses to tell me anything since I'm the one that is suppose to do the work. 

I have searched around, and the only thing I found was Linked List, and it doesn't even work with arrays. I simply can't find anything anywhere of other Dynamic Arrays. Could someone explain to me what are the types of dynamic arrays (if there are more then ArrayList) and maybe give me some insight about it? If not, just the types would be good. Really struggling here...

Thanks.

EDIT: Turns out she wants Dynamic data structures, not arrays. so imagine everytime you read arrays up there it was written "data structures". sorry

EDIT: So let me see if I got it all: I need to talk about java collections, java vectors, and Lists (talking a litle bit of all the List types). Anything missing?

Answer: 
Okay, I finally solve the problem.

In models I had to declare how the db is, as always...

(models.py)

```
# Create your models here.
from mongoengine import *
class User(Document):
    email = StringField(required=True)
    first_name = StringField(max_length=50)
    last_name = StringField(max_length=50)
class Comment(EmbeddedDocument):
    content = StringField()
    name = StringField(max_length=120)

class Post(Document):
    title = StringField(max_length=120, required=True)
    author = ReferenceField(User)
    tags = ListField(StringField(max_length=30))
    comments = ListField(EmbeddedDocumentField(Comment))
    meta = {'allow_inheritance': True}

class TextPost(Post):
    content = StringField()

class ImagePost(Post):
    image_path = StringField()

class LinkPost(Post):
    link_url = StringField()

```

In views.py(or python console either)....

```
from django.shortcuts import render 
# Create your views here.
from django.http import HttpResponse  
from game.models import *  //Import the models 
from mongoengine import * //Import things like connect

def testview(request):  
    connect('reborn')//Connect to DB
    //Let's add some data!
    article = User(email = 'test@title.com',first_name = 'test content')
    article.save()
    return HttpResponse("SAVED")

```
Try type `import * from app.models` in shell before adding data.