What is the purpose of `convertView` in ListView adapter?
<p>In android, I usually use <code>MyAdapter extends ArrayAdapter</code> to create view for the <code>ListView</code>, and as a result, I have to override the function </p>

<pre><code>public View getView(int position, View convertView, ViewGroup parent) {
    // somecode here
}
</code></pre>

<p>However, i don't know exactly what <code>convertView</code> and <code>parent</code> do! Does anyone have a suggestion? More detail, more help! Thanks!</p>
