安卓：FastScrolling SectionIndexer getSections（）被调用一次 [英] Android: FastScrolling SectionIndexer getSections() is called only once
问题描述
我已经创建了一个的ListView 这是使用 FastScroll 。 （参见图）当用户点击任何按钮下的（即所有曲目，艺术家，专辑），每次下面的自定义ArrayAdater叫
ArrayAdapter＆LT;字符串＆GT;适配器=新ScrollIndexListAdapter（Listing.this，元素）;
// $ C $下ScrollIndexListAdapter低于
和相同的ListView被更新。
问题：根据我的Android调查， getSections（）方法被调用一次（即只有当第一时间ScrollIndexListAdapter被调用）。
这一次的部分填充和放大器;在fastScrolling完美的作品。
但是，当我点击艺术家/专辑的 getSections更新的ListView（）方法不叫。所以较早部分被使用，且FastScrolling仍显示旧字母表previews
那么，如何才能让部分得到更新时，每次在ListView更新？
有一个 setSections（）的方法，但我无法找到如何使用它。
$ C $下ScrollIndexListAdapter类：
公共类ScrollIndexListAdapter扩展ArrayAdapter工具
SectionIndexer {
//为SectionIndexer列表快速滚动变量
HashMap的＆LT;字符串，整数＆GT; alphaIndexer;
的String []段;
私有静态的ArrayList＆LT;字符串＆GT;名单=新的ArrayList＆LT;字符串＆GT;（）;
公共ScrollIndexListAdapter（上下文的背景下，ArrayList的＆LT;字符串＆GT;列表）{
超（背景下，android.R.layout.simple_list_item_1，android.R.id.text1，
清单）;
this.list.clear（）;
this.list.addAll（名单）;
/ *
*环境SectionIndexer
* /
alphaIndexer =新的HashMap＆LT;字符串，整数＆GT;（）;
INT大小=则为list.size（）;
为（中间体X = 0 X - 其中;大小; X ++）{
字符串s =（字符串）list.get（X）;
//获取轨道的第一字符
串CH = s.substring（0，1）;
//转换为大写，否则小写-z进行排序
//后上A-Z
CH = ch.toUpperCase（）;
如果（！alphaIndexer.containsKey（CH））{
alphaIndexer.put（CH，X）;
}
}
设置＆LT;字符串＆GT; sectionLetters = alphaIndexer.keySet（）;
//创建一个列表从集合进行排序
ArrayList的＆LT;字符串＆GT; sectionList =新的ArrayList＆LT;字符串＆GT;（
sectionLetters）;
Collections.sort（sectionList）;
部分=新的String [sectionList.size（）];
sectionList.toArray（段）;
}
/ *
*方法AphhabelIndexer的列表快速滚动
* /
@覆盖
公众诠释getPositionForSection（INT部分）{
串字母=（字符串）部分[第]
返回alphaIndexer.get（函）;
}
@覆盖
公众诠释getSectionForPosition（INT位置）{
串字母=（字符串）第[位置]
返回alphaIndexer.get（函）;
}
@覆盖
公共对象[] getSections（）{
返回段;
}
}
看来，最新的FastScroll版本不存在这样的问题。但是，你的情况，有一个转身。当设置适配器到ListView，禁用和启用快速滚动。请参见下面的code：
适配器=新ScrollIndexListAdapter（这个数据）;
listView.setFastScrollEnabled（假）;
listView.setAdapter（适配器）;
listView.setFastScrollEnabled（真正的）;
I've created a ListView which is using FastScroll. (see pic) When the user clicks any of the below Button (viz. All Tracks, Artists, Album), everytime the following custom ArrayAdater is called
ArrayAdapter<String> adapter = new ScrollIndexListAdapter(Listing.this, elements);
//Code for ScrollIndexListAdapter is below
and the same ListView is updated.
PROBLEM: According to my investigation in Android, the getSections() method is called only once (i.e. only when the first time ScrollIndexListAdapter is called).
This time the sections are populated & the fastScrolling works perfectly.
But when I update the ListView by clicking on Artists/Album, the getSections() method is not called. So the older sections are used, and the FastScrolling still shows previews of old alphabets.
So, how can I make sections get updated everytime when the ListView is updated?
There is a setSections() method, but I'm not able to find how to use it.
Code for ScrollIndexListAdapter class:
public class ScrollIndexListAdapter extends ArrayAdapter implements
SectionIndexer {
// Variables for SectionIndexer List Fast Scrolling
HashMap<String, Integer> alphaIndexer;
String[] sections;
private static ArrayList<String> list = new ArrayList<String>();
public ScrollIndexListAdapter(Context context, ArrayList<String> list) {
super(context, android.R.layout.simple_list_item_1, android.R.id.text1,
list);
this.list.clear();
this.list.addAll(list);
/*
* Setting SectionIndexer
*/
alphaIndexer = new HashMap<String, Integer>();
int size = list.size();
for (int x = 0; x < size; x++) {
String s = (String) list.get(x);
// Get the first character of the track
String ch = s.substring(0, 1);
// convert to uppercase otherwise lowercase a -z will be sorted
// after upper A-Z
ch = ch.toUpperCase();
if (!alphaIndexer.containsKey(ch)) {
alphaIndexer.put(ch, x);
}
}
Set<String> sectionLetters = alphaIndexer.keySet();
// create a list from the set to sort
ArrayList<String> sectionList = new ArrayList<String>(
sectionLetters);
Collections.sort(sectionList);
sections = new String[sectionList.size()];
sectionList.toArray(sections);
}
/*
* Methods for AphhabelIndexer for List Fast Scrolling
*/
@Override
public int getPositionForSection(int section) {
String letter = (String) sections[section];
return alphaIndexer.get(letter);
}
@Override
public int getSectionForPosition(int position) {
String letter = (String) sections[position];
return alphaIndexer.get(letter);
}
@Override
public Object[] getSections() {
return sections;
}
}
It seems that latest FastScroll version doesn't have that problem. But, in your case, there's a turn around. When setting the adapter to the ListView, disable and enable the fast scrolling. See the code below:
adapter = new ScrollIndexListAdapter(this, data);
listView.setFastScrollEnabled(false);
listView.setAdapter(adapter);
listView.setFastScrollEnabled(true);
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