Java: Dynamically Fill Array (not vector/ArrayList)

Question

I'm trying to figure out if there's someway for me to dynamically fill an array of objects within a class, without using array initialization. I'd really like to avoid filling the array line by line. Is this possible given the code I have here?

final class Attributes {

    private final int TOTAL_ATTRIBUTES = 7;

    Attribute agility;
    Attribute endurance;
    Attribute intelligence;
    Attribute intuition;
    Attribute luck;
    Attribute speed;
    Attribute strength;

    private Attributes[] attributes; //array to hold objects

    private boolean initialized = false;

    public Attributes() {
        initializeAttributes();
        initialized = true;

        store(); //method for storing objects once they've been initialized.

    }

    private void initializeAttributes() {
        if (initialized == false) {
            agility = new Agility();
            endurance = new Endurance();
            intelligence = new Intelligence();
            intuition = new Intuition();
            luck = new Luck();
            speed = new Speed();
            strength = new Strength();
        }
    }

    private void store() {
        //Dynamically fill "attributes" array here, without filling each element line by line.
    }
}

Just to clarify.. "You want to add all member variables typed Attributes to an array?" this is what you mean by dynamic rt? — Dileep
– Dileep, Commented Jun 23, 2011 at 18:01
I think you want to implement yourself whatever is already implemented in Java Collection, you could take a look at OpenJDK and see how they have done it. — Hernán Eche
– Hernán Eche, Commented Jun 23, 2011 at 18:06

Rocky Pulley · Accepted Answer · 2011-06-23 18:05:02Z

3

attributes = new Attributes[sizeOfInput];

for (int i=0; i<sizeOfInput; i++) {
    attributes[i] = itemList[i];
}

Also, FYI you can add things to an ArrayList and then call toArray() to get an Array of the object.

answered Jun 23, 2011 at 18:05

Rocky Pulley

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Comments

jiggy · Accepted Answer · 2011-06-23 18:05:54Z

1

There is a short Array initialization syntax:

attributes = new Attribute[]{luck,speed,strength,etc};

answered Jun 23, 2011 at 18:05

jiggy

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1 Comment

zeboidlund Over a year ago

Yeah, I was thinking about that, but I'm looking for something much more dynamic.

Bala R · Accepted Answer · 2011-06-23 18:07:30Z

0

 Field[] fields =  getClass().getDeclaredFields();
 ArrayList<Attrubute> attributesList = new ArrayList<Attrubute>();
 for(Field f : fields)
 {
     if(f.getType() == Attrubute.class)
     {
         attributesList.add((Attrubute) f.get(this));
     }
 }
 attributes = attributesList.toArray(new Attrubute[0]);

edited Jun 23, 2011 at 18:07

answered Jun 23, 2011 at 18:02

Bala R

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4 Comments

mihi Over a year ago

while Reflection "solves" the problem here, it is more likely a design problem here :) And using getDeclaredFields might make it work better against non-public fields.

Bala R Over a year ago

@mihi I can't comment on the design but using getDeclaredFields() does make sense.

zeboidlund Over a year ago

one thing I don't understand is..why don't I just use the array to transfer the values, rather than the ArrayList?

Bala R Over a year ago

@Holland array cannot grow dynamically like an ArrayList can. I you are going to have fixed number of attributes, you can declare an array of that size and use it.

David Kroukamp · Accepted Answer · 2012-08-09 12:24:32Z

-1

You can use a HashMap<String,Attribute>

edited Aug 9, 2012 at 12:24

David Kroukamp

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answered Jun 23, 2011 at 17:56

Nathan Romano

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3 Comments

zeboidlund Over a year ago

How would a HashMap help in this case?

demongolem Over a year ago

Everyone else has code samples, maybe you could throw one in too

Kartik Domadiya Over a year ago

This is really a comment, not an answer to the question. Please use "add comment" to leave feedback for the author.

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