我曾想利用ArrayAdapter中的getView來獲取ListView中每一個item的View對象。結果是,不管我怎麼對View對象進行更改都不產生影響。不會變是理所固然的,由於getView,實際上是」createView「。下面是我參考的源代碼:java
public View getView(int position, View convertView, ViewGroup parent) { return createViewFromResource(position, convertView, parent, mResource); } private View createViewFromResource(int position, View convertView, ViewGroup parent, int resource) { View view; TextView text; if (convertView == null) { view = mInflater.inflate(resource, parent, false); } else { view = convertView; } try { if (mFieldId == 0) { // If no custom field is assigned, assume the whole resource is a TextView text = (TextView) view; } else { // Otherwise, find the TextView field within the layout text = (TextView) view.findViewById(mFieldId); } } catch (ClassCastException e) { Log.e("ArrayAdapter", "You must supply a resource ID for a TextView"); throw new IllegalStateException( "ArrayAdapter requires the resource ID to be a TextView", e); } T item = getItem(position); if (item instanceof CharSequence) { text.setText((CharSequence)item); } else { text.setText(item.toString()); } return view; }
從代碼來看,確定不多是我所想的那樣。若是convertView等於null,每次調用getView都是返回一個新的對象。可是,爲何呢?ui
個人理解是,Adapter做爲Controller,向下從Model層中獲取數據,向上向View層提供對象。做爲給予者,不該該瞭解View層的信息。因此,經過Adapter來獲取View層的對象,這自己就是不可取的。spa