实现 Adapter 的 getView 效率提高

Adapter

 

显示每条数据的 XML 布局文件 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="horizontal"> <ImageView android:id="@+id/icon" android:layout_width="48dip" android:layout_height="48dip" /> <TextView android:id="@+id/text" android:layout_gravity="center_vertical" android:layout_width="0dip" android:layout_weight="1.0" android:layout_height="wrap_content" /> </LinearLayout>

 

滚动时, 频繁调用

 

public View getView(int pos, View convertView, ViewGroup parent){ View item = mInflater.inflate(R.layout.list_item, null); ((TextView) item.findViewById(R.id.text)). setText(DATA[pos]); ((ImageView) item.findViewButId(R.id.icon)). setImageBitmap((pos & 1) == 1 ? mIcon1 : mIcon2); return item; } ..简单的方法, 最慢最不实用

 

..利用convertView回收视图

 

public View getView(int pos, View convertView, ViewGroup parent){ if (convertView == null) { convertView = mInflater.inflate( R.layout.list_item, null); } ((TextView) convertView.findViewById(R.id.text)). setText(DATA[pos]); ((ImageView) convertView.findViewButId(R.id.icon)). setImageBitmap((pos & 1) == 1 ? mIcon1 : mIcon2); return convertView; } ..................................再度优化, 效率提高 200%

 

static class ViewHolder { TextView text; ImageView icon; }

 

public View getView(int pos, View convertView, ViewGroup parent){ ViewHolder holder; if (convertView == null) { convertView = mInflater.inflate(R.layout.list_item, null); holder = new ViewHolder(); holder.text = (TextView) convertView.findViewById( R.id.text)); holder.icon = (ImageView) convertView.findViewButId( R.id.icon)); convertView.setTag(holder); } else { holder = (ViewHolder) convertView.getTag(); } holder.text.setText(DATA[pos]); holder.icon.setImageBitmap((pos & 1) == 1 ? mIcon1 : mIcon2); return convertView; }