[newbie] Vector of arrays...how to add them

[Jon Camilleri]

Any idea how to add some object to my Vector? As you might notice I'm trying to address what seems to be a common issue...a dynamically expanding array of objects, ideally of any type.

    
...
ArrayList<int[]> myArrayObjects = new ArrayList <int[]>();
			Integer[] myNumbers = new Integer[5];
			
			for (int i = 0; i < myNumbers.length; i++)
			{
				myNumbers[i] = i + 1;
			}
			
			myArrayObjects.add(myNumbers); 
                       //this is where I'm stuck...er... Error: The method add(int[]) in the type ArrayList<int[]> is not applicable for the arguments (Integer[])

...

private static Vector<?> _growingArray = new Vector();

Related links: http://www.javaworld.com/javaworld/jw-08-1999/jw-08-cooltools.html

[Steve Luke]

You are trying to mix a List of arrays of the primitive ints (int[]) with arrays of the Object Integer (Integer[]). An Integer is not the same as an int. You should make them both refer to the same data type:

            ArrayList<int[]> myArrayObjects = new ArrayList <int[]>();
            int[] myNumbers = new int[5];

- or -

            ArrayList<Integer[]> myArrayObjects = new ArrayList <Integer[]>();
            Integer[] myNumbers = new Integer[5];

[Mike Simmons]

Jon Camilleri wrote:Any idea how to add some object to my Vector?

Um, have you tried the add() method?

Jon Camilleri wrote:As you might notice I'm trying to address what seems to be a common issue...a dynamically expanding array of objects, ideally of any type.

A common issue twenty or more years ago, maybe.

I tried reading the ten-year-old article you linked to, but I nearly died of boredom halfway through. I'm still recovering.

Look, whatever ancient text you're reading that talks about Vectors, please, just burn it and upgrade to something published in the current millenium.

[Campbell Ritchie]

Mike Simmons wrote:. . . in the current millenium.

If we are sticking to things from the current millennium, don't use Vector. It is generally regarded as legacy code. Use one of the more modern implementation of List<E>. Most likely ArrayList<E>.

[Mike Simmons]

Yes, that was my point. One of them, at least.

[Jon Camilleri]

Thanks

[Jon Camilleri]

Thanks for your updates Well, actually I did try a modern day ArrayList, which is one of my favorite constructs in other languages, but I can't find a way of creating an array of integers:

    
ArrayList<int[]> myArrayObjects = new ArrayList <int[]>();
			Integer[] myNumbers = new Integer[5];
			....
			myArrayObjects.addAll(myNumbers[]); 
                        //The method addAll(Collection<? extends int[]>) in the type ArrayList<int[]> is not applicable for the arguments (Integer)

Related Links:
1. http://www.roseindia.net/java/beginners/array_list_demo.shtml
2. The API http://java.sun.com/javase/6/docs/api/


Well the "solution" was quite simple... An ArrayList made up of an ArrayList of Integer (not int)

...
ArrayList<ArrayList><Integer>> myArrayObjects = new ArrayList <ArrayList><Integer>>();
			ArrayList<Integer> myNumbers = new ArrayList<Integer>();
			
			for (int i = 0; i < 100; i++)
			{
				myNumbers.add(i);
			}
			
			//Add an ArrayList made up of an ArrayList of Integer objects.
			myArrayObjects.add(myNumbers);
			System.out.println("Size: " + myArrayObjects.size());
...

[Campbell Ritchie]

That roseindia demonstration was not really useful. It didn't tell you to declare your object by its interface. You would do better to declare

List<List><Integer>> intList;
 . . .
intList = new ArrayList<List><Integer>>();
 . . .
intList.add(new ArrayList<Integer>());

For some reason, which I don't know, I am getting >< when I typed <. Readers: please check for that error.

Anyway, why don't you declare the List to take int[] elements?

import java.util.List;
import java.util.ArrayList;

public class IntArrayListDemo
{
    private List<int[]> intList;
    
    public static void main(String[] args)
    {
        new IntArrayListDemo(args).go();
    }//end main
    
    public IntArrayListDemo(String[] args)
    {
        intList = new ArrayList<int[]>();
        int[] numbers = new int[args.length];
        intList.add(numbers);
        for (int i = 0; i < args.length; i++)
        {
            numbers[i] = Integer.parseInt(args[i]);
        }
    }//end constructor
    
    private void go()
    {
        for (int[] numbers : intList)
        {
            System.out.printf("%n%s : ", numbers);
            for (int i : numbers)
            {
                System.out.printf("%d ", i);
            }//end inner for-each
        }//end outer for-each   
    }//end go
}//end class

java IntArrayListDemo 123 234 345 456 567 678 789

And see for yourself what happens.

[Jon Camilleri]

Campbell Ritchie wrote:That roseindia demonstration was not really useful. It didn't tell you to declare your object by its interface. You would do better to declare

List<List><Integer>> intList;
 . . .
intList = new ArrayList<List><Integer>>();
 . . .
intList.add(new ArrayList<Integer>());

For some reason, which I don't know, I am getting >< when I typed <. Readers: please check for that error.

Anyway, why don't you declare the List to take int[] elements?

import java.util.List;
import java.util.ArrayList;

public class IntArrayListDemo
{
    private List<int[]> intList;
    
    public static void main(String[] args)
    {
        new IntArrayListDemo(args).go();
    }//end main
    
    public IntArrayListDemo(String[] args)
    {
        intList = new ArrayList<int[]>();
        int[] numbers = new int[args.length];
        intList.add(numbers);
        for (int i = 0; i < args.length; i++)
        {
            numbers[i] = Integer.parseInt(args[i]);
        }
    }//end constructor
    
    private void go()
    {
        for (int[] numbers : intList)
        {
            System.out.printf("%n%s : ", numbers);
            for (int i : numbers)
            {
                System.out.printf("%d ", i);
            }//end inner for-each
        }//end outer for-each   
    }//end go
}//end class

java IntArrayListDemo 123 234 345 456 567 678 789

And see for yourself what happens.

Thanks, that seemed to work
My code did not seem to work when I tried implementing something on the same lines of thought (see above posts).

[Campbell Ritchie]

You're welcome