前面两篇学习适配器的时候用的就是listview，主要是简单的添加，今晚在看了下listview滚动状态事件和动态加载数据，一个小demo。
listview的滚动状态主要有三种，onScrollStateChanged
SCROLL_STATE_IDLE 空闲状态 ，既是滚动停止状态
SCROLL_STATE_FLING 滚动状态 ， 既是滚动中的状态
SCROLL_STATE_TOUCH_SCROLL 触摸后滚动 ， 刚开始滚动的状态
/**
* Callback method to be invoked while the list view or grid view is being scrolled. If the
* view is being scrolled, this method will be called before the next frame of the scroll is
* rendered. In particular, it will be called before any calls to
* {@link Adapter#getView(int, View, ViewGroup)}.
*
* @param view The view whose scroll state is being reported
*
* @param scrollState The current scroll state. One of {@link #SCROLL_STATE_IDLE},
* {@link #SCROLL_STATE_TOUCH_SCROLL} or {@link #SCROLL_STATE_IDLE}.
*/
onScroll 函数应该是滚动完成后的回调函数
firstVisibleItem 该页面第一个可视索引
visibleItemCount 该页面显示的列表个数
totalItemCount 整个listview 的item 个数
源码注释
* Callback method to be invoked when the list or grid has been scrolled. This will be
* called after the scroll has completed
* @param view The view whose scroll state is being reported
* @param firstVisibleItem the index of the first visible cell (ignore if
* visibleItemCount == 0)
* @param visibleItemCount the number of visible cells
* @param totalItemCount the number of items in the list adaptor
adapter.notifyDataSetChanged() 是适配器数据改变之后需要通过该函数，通知listview
知道这两个回调，就可以做到动态加载数据了，既是在滚动完成后，判断是否到达末尾，如果到达末尾就添加进一个数据，然后通知listview更新。
public class ArrayAdapterActivity extends Activity {
private ListView listView;
private ArrayAdapter<String> adapter;
private ArrayList<String> list;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_array_adapter);
listView = (ListView)findViewById(R.id.listView3);
list = new ArrayList<String>();
adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1,getData());
listView.setAdapter(adapter);
listView.setOnScrollListener(new AbsListView.OnScrollListener() {
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
switch(scrollState){
case AbsListView.OnScrollListener.SCROLL_STATE_IDLE:{
Log.i("scroll","空闲状态");
break;
}
case AbsListView.OnScrollListener.SCROLL_STATE_FLING:{
Log.i("scroll","滚动状态");
break;
}
case AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL:{
Log.i("scroll","触摸后滚动");
break;
}
}
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if(firstVisibleItem + visibleItemCount == totalItemCount){
Log.i("scroll","到达底部");
list.add(""+list.size());
adapter.notifyDataSetChanged();
}
}
});
}
ArrayList<String> getData(){
for(int i =0;i<40;i++) {
list.add("" + i);
}
return list;
}
}