Update ArrayAdapter in Android

Question

How do you update an ArrayAdapter without losing the scrolling position?

This is how I currently do it. I create an update method in the ArrayAdapter subclass which does the following:

public void update(List<MyEntity> entities) {
    for (MyEntity entity : entities) {
        int position = this.getPosition(entity);
        if (position >= 0) {
            final MyEntity outdateEntity = this.getItem(position);
            this.insert(entity, position);
            this.remove(outdateEntity);
        } else {
            this.insert(entity, 0);         
        }
    }
}

public int getPosition(MyEntity updatedEntity) {
    for (int i = 0; i < this.getCount(); i++) {
        if (this.getItem(i).getId() == updatedEntity.getId()) {
            return i;
        }
    }
    return -1;
}

However, this seems awfully inefficient and error-prone. Is there a better way?

mreichelt · Accepted Answer · 2010-12-06 21:06:47Z

2

Why do you not extend BaseAdapter in the first place? There you just have to update your list internally and then call notifyDataSetChanged()... :-)

answered Dec 6, 2010 at 21:06

mreichelt

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2 Comments

hpique Over a year ago

Wouldn't that reset the current scrolling position?

mreichelt Over a year ago

Normally not - the list should stay where it is (at least if the appropriate scrolling position is not out of range of the list).

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