不论是那种适配器模式,也不管是Listview也好还是gridview也好,对他们填充数据,都是分三步走。
第一:创建一个数据填充的对象,可以是ListView, GridView, Gallery。
listView=(ListView) findViewById(R.id.listview_simple);
第二步:创建一个数据填充器,可以是BaseAdapter、SimpleAdapter,也可以是与数据库相关联的CursorAdapter。
例如:SimpleAdapter可以使用系统封装好的,你也可以自己去继承一个Simpleadapter,来重写其中的方法。继承 simpleadapter的好处在于,你可以对listitem中每个单一的控件设置监听事件等等一系列操作。如果用的是系统封装好的就有点爱莫能助了。
直接使用系统封装的:
SimpleAdapter simpleAdapter = new SimpleAdapter( this, data, R.layout.simple_item, new String[] { "name", "info" }, new int[] { R.id.simple_name, R.id.simple_info });
重写系统的simpleadpter:
public class ListSimpleAdpter extends SimpleAdapter{ //要使用到的数据源 private List<MAP><STRING, object="">> data=new ArrayList</STRING,></MAP><MAP><STRING, object="">>(); //填充数据的资源文件 private int resource; private String[] from; private Context context; public ListSimpleAdpter(Context context, List</STRING,></MAP><MAP><STRING, object="">> data, int resource, String[] from, int[] to) { super(context, data, resource, from, to); this.context=context; this.data=data; this.resource=resource; this.from=from; } //item的总行数 @Override public int getCount() { // TODO Auto-generated method stub return data==null?0:data.size(); } //item对象 @Override public Object getItem(int position) { // TODO Auto-generated method stub return position; } //item的id @Override public long getItemId(int position) { // TODO Auto-generated method stub return position; } //绘制每一个item @Override public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub Holder holder = null; if(convertView==null) { convertView=LayoutInflater.from(context).inflate(resource, null); holder=new Holder(); holder.imageView=(ImageView) convertView.findViewById(R.id.listitem_pic); holder.title=(TextView) convertView.findViewById(R.id.listitem_title); holder.content=(TextView) convertView.findViewById(R.id.listitem_content); convertView.setTag(holder); }else{ holder=(Holder) convertView.getTag(); } holder.imageView.setImageResource(Integer.parseInt(data.get(position).get(from[0]).toString())); holder.title.setText(data.get(position).get(from[1]).toString()); holder.content.setText(data.get(position).get(from[2]).toString()); return convertView; } class Holder{ ImageView imageView; TextView title; TextView content; } }
这里对于Adapter的优化,用的很古老的ViewHolder、ViewCache办法:
public View getView(int position, View convertView, ViewGroup parent) { // TODO Auto-generated method stub Holder holder = null; if(convertView==null) { convertView=LayoutInflater.from(context).inflate(resource, null); holder=new Holder(); holder.imageView=(ImageView) convertView.findViewById(R.id.listitem_pic); holder.title=(TextView) convertView.findViewById(R.id.listitem_title); holder.content=(TextView) convertView.findViewById(R.id.listitem_content); convertView.setTag(holder); }else{ holder=(Holder) convertView.getTag(); } holder.imageView.setImageResource(Integer.parseInt(data.get(position).get(from[0]).toString())); holder.title.setText(data.get(position).get(from[1]).toString()); holder.content.setText(data.get(position).get(from[2]).toString()); return convertView; } class Holder{ ImageView imageView; TextView title; TextView content; }
或者使用HashMap做缓存的方法:
HashMap<INTEGER, view=""> m = new HashMap<I<span id="transmark"></span>NTEGER, view="">(); public View getView(int position, View view, ViewGroup parent) { View convertView = m.get(position); if (convertView != null) { return convertView; } else { convertView=LayoutInflater.from(context).inflate(resource, null); ImageView imageView=(ImageView) convertView.findViewById(R.id.listitem_pic); TextView title=(TextView) convertView.findViewById(R.id.listitem_title); TextView content=(TextView) convertView.findViewById(R.id.listitem_content); m.put(position, convertView); } }
第三步:将数据填充到对象中去
listView.setAdapter(simpleAdapter);
这样就完成了数据填充器的数据填充。
还有ArrayAdapter, BaseAdapter, CursorAdapter, HeaderViewListAdapter, ListAdapter,ResourceCursorAdapter, SimpleAdapter, SimpleCursorAdapter, SpinnerAdapter, WrapperListAdapter.SimpleCursorTreeAdapter、
二级树相关的SimpleExpandableListAdapter、BaseExpandableListAdapter等等。