expandable multidimensional ArrayList or Multidimensional Arrays?

[Vladimir Korabelnikoff]

So I need to be able to store data from an xml file in a collection.

The output is the equivalent of a two-dimensional table.

I need to be able to EXPAND it, so Array is almost not an option.

Would I be better off trying to use a multidimensional arraylist?

Or, would I be better off creating a new array (and copying the other array to the new one) every time I add an element to it?


Please let me know ;) Thanks guys!

[Paul Clapham]

Vladimir Korabelnikoff wrote:Or, would I be better off creating a new array (and copying the other array to the new one) every time I add an element to it?

But that's basically what an ArrayList does. So if that's what you need then use an ArrayList.

[Vladimir Korabelnikoff]

Paul Clapham wrote:

Vladimir Korabelnikoff wrote:Or, would I be better off creating a new array (and copying the other array to the new one) every time I add an element to it?

But that's basically what an ArrayList does. So if that's what you need then use an ArrayList.

Thanks a bunch! I'll look into how to make ArrayLists's multidimensional!

[Campbell Ritchie]

There is no such thing as a multidimensional array, only an array of arrays. There is no such thing as a multidimensional ArrayList, but you can have a List of Lists.

[Vladimir Korabelnikoff]

Campbell Ritchie wrote:There is no such thing as a multidimensional array, only an array of arrays. There is no such thing as a multidimensional ArrayList, but you can have a List of Lists.

Oh Really? That's awesome! Can you put any type of Collection inside of a Collection? Or is it just Lists?

[Rob Spoor]

Collections can hold any objects, and that includes other collections. At least if you use the right generic type:

List<List<Integer>> intLists; // a list of lists of integers
List<Set<Integer>> intSets; // a list of sets of integers
Set<List<Long>> longLists; // a set of lists of longs
// etc

[Vladimir Korabelnikoff]

Rob Spoor wrote:Collections can hold any objects, and that includes other collections. At least if you use the right generic type:

List<List<Integer>> intLists; // a list of lists of integers
List<Set<Integer>> intSets; // a list of sets of integers
Set<List<Long>> longLists; // a set of lists of longs
// etc

Thanks for that. I created an ArrayList of ArrayLists.

However, I have a nested for loop where I read my XML, and I have no idea how to name the sub-Lists in the for loop.

ArrayList<ArrayList<String>> listOlists = new ArrayList<ArrayList<String>>();
foreach(Row) {
  ArrayList<String> singleLists = new ArrayList<String>();
  foreach () {
    singleList.add(((Node) fstNm.item(0)).getNodeValue());
  }
  listOlists.add(singleList);
}

That's alright for the first loop, but what happens when it comes back a second time? singleLists should be renamed, if I'm correct.

I'm just not sure how :l Thanks for your help, guys.

[Campbell Ritchie]

You ought to have declared it as Rob told you. You can iterate a List<List<Foo>> in a for-each loop, with each element found being a List<Foo>. Like this:

List<List<Foo>> fooLists = new ArrayList<List<Foo>>();
// ...
List<Foo> linkedFoos = new LinkedList<Foo>(); // You can write <> in Java7
// ...
fooLists.add(linkedFoos);
// ...
List<foo> arrayedFoos = new ArrayList<foo>();
// ...
fooLists.add(arrayedFoos);
// ...
for (List<Foo> lf : fooList)
{
   for (Foo f : lf)
   {
      System.out.println(f);
   }
}

[Vladimir Korabelnikoff]

Campbell Ritchie wrote:You ought to have declared it as Rob told you. You can iterate a List<List<Foo>> in a for-each loop, with each element found being a List<Foo>. Like this:

List<List<Foo>> fooLists = new ArrayList<List<Foo>>();
// ...
List<Foo> linkedFoos = new LinkedList<Foo>(); // You can write <> in Java7
// ...
fooLists.add(linkedFoos);
// ...
List<foo> arrayedFoos = new ArrayList<foo>();
// ...
fooLists.add(arrayedFoos);
// ...
for (List<Foo> lf : fooList)
{
   for (Foo f : lf)
   {
      System.out.println(f);
   }
}

Awesome! Thank you guys so much! You are legends! I have gotten it to work. I now read the XML, and put into a List of Lists, then return that back to the main class.

Now I have to figure out how to sort through them (by certain fields)/

This is the XML:

<?xml version="1.0"?>
<company>
	<employee>
		<firstname>Tom</firstname>
		<lastname>Cruise</lastname>
		<streetaddress>32 The Spur</streetaddress>
		<state>QLD</state>
		<country>Australia</country>
		<ph>5555 5555</ph>
		<description>Tom called on Friday afternoon, regarding a problem with his anti-virus software.</description>
                <date>737596800</date>
	</employee>
	<employee>
		<firstname>Tom</firstname>
		<lastname>Cruise</lastname>
		<streetaddress>32 The Spur</streetaddress>
		<state>QLD</state>
		<country>Australia</country>
		<ph>5555 5555</ph>
		<description>Tom called on Friday afternoon, regarding a problem with his anti-virus software.</description>
                <date>743385600</date>
	</employee>
	<employee>
		<firstname>Tom</firstname>
		<lastname>Cruise</lastname>
		<streetaddress>32 The Spur</streetaddress>
		<state>QLD</state>
		<country>Australia</country>
		<ph>5555 5555</ph>
		<description>Tom called on Friday afternoon, regarding a problem with his anti-virus software.</description>
                <date>754704000</date>
	</employee>
</company>

I need to be able to order it by date (ascending, and descending). The date is of course, in UNIX timestamp.

Note that I'm not sorting XML, I'm sorting through the List of Lists.

Can you guy please point me in the right direction? Thanks so much for your help.

[Joanne Neal]

Have you been told to use a list of lists ?
The better solution is to create a Company class and an Employee class and the Company class will contain a list of Employees.

Off topic - your list of employees reminds me of a Monty Python sketch.

[Vladimir Korabelnikoff]

Joanne Neal wrote:Have you been told to use a list of lists ?
The better solution is to create a Company class and an Employee class and the Company class will contain a list of Employees.

Off topic - your list of employees reminds me of a Monty Python sketch.

I'm sure I have been told to do lists, and that's what I'm using? Maybe I missed something.

I'm not actually sure what you mean by having a class for companies and employees. I only need one company, and multiple employees.

Edit: Haha, why so? I've only seen one Monty Python sketch (The Holy Grail) - The funniest stuff ever.

[Winston Gutkowski]

Vladimir Korabelnikoff wrote:I'm not actually sure what you mean by having a class for companies and employees. I only need one company, and multiple employees.

So, you have a Company class and an Employee class; and inside your Company class, you have a member field something like:

private List<Employee> employees = new ArrayList<Employee>();

Winston

[Joanne Neal]

Vladimir Korabelnikoff wrote:Edit: Haha, why so? I've only seen one Monty Python sketch (The Holy Grail) - The funniest stuff ever.

Monty Python Bruce sketch