我正在尝试按NewsAdapter对象上的publishedAt变量对Articles_Map数组中的每个条目进行排序。每次使用publishedAt方法添加新条目后，我都需要按addAll排序。这是我的代码：
ListNewsActivity ：
public class ListNewsActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
/* ... */
// parameters for Sources endpoint
String category = "sport";
String language = "en";
String country = "us";
// Sources endpoint
Sources_Interface client_sources = NewsAPI_Adapter.createService(Sources_Interface.class);
Call<Sources_Map> call_sources = client_sources.getData(category, language, country);
call_sources.enqueue(new Callback<Sources_Map>() {
@Override
public void onResponse(Call<Sources_Map> call_sources, Response<Sources_Map> response) {
if (response.body() != null) {
final NewsAdapter nAdapter = new NewsAdapter(ListNewsActivity.this,
R.layout.article_layout);
for (final Sources_Content source : response.body().sources) {
if (source.sortBysAvailable.contains("latest")) {
// Articles endpoint
NewsAPI_Interface client = NewsAPI_Adapter.createService(NewsAPI_Interface.class);
Call<NewsAPI_Map> call = client.getData(source.id, "17f8ddef543c4c81a9df2beb60c2a478");
call.enqueue(new Callback<NewsAPI_Map>() {
@Override
public void onResponse(Call<NewsAPI_Map> call, Response<NewsAPI_Map> response) {
if (response.body() != null) {
ExpandableHeightGridView gv_content = (ExpandableHeightGridView) findViewById(R.id.gv_content);
nAdapter.addAll(response.body().articles);
gv_content.setAdapter(nAdapter);
gv_content.setExpanded(true);
}
}
@Override
public void onFailure(Call<NewsAPI_Map> call, Throwable t) {
System.out.println("An error ocurred!\n" +
"URL: " + call.request().url() + "\n" +
"Cause: " + t.getCause().toString());
}
});
}
}
}
}
@Override
public void onFailure(Call<Sources_Map> call_sources, Throwable t) {
System.out.println("An error ocurred!");
}
});
}
}
NewsAdapter ：
public class NewsAdapter extends ArrayAdapter<Articles_Map> {
Context mContext;
public NewsAdapter(Context c, int resource) {
super(c, resource);
this.mContext = c;
}
public NewsAdapter(Context c, int resource, List<Articles_Map> articles) {
super(c, resource, articles);
this.mContext = c;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// get the property we are displaying
Articles_Map article = getItem(position);
// get the inflater and inflate the XML layout for each item
LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
View view = inflater.inflate(R.layout.article_layout, null);
ImageView thumbnail = (ImageView) view.findViewById(R.id.thumbnail);
TextView title = (TextView) view.findViewById(R.id.title);
TextView description = (TextView) view.findViewById(R.id.description);
Picasso.with(mContext).load(article.urlToImage).into(thumbnail);
title.setText(article.title);
description.setText(article.description);
return view;
}
}
Articles_Map ：
public class Articles_Map {
String title;
String description;
String url;
String urlToImage;
Date publishedAt;
public Articles_Map(String title, String description, String url, String urlToImage, Date publishedAt) {
this.title = title;
this.description = description;
this.url = url;
this.urlToImage = urlToImage;
this.publishedAt = publishedAt;
}
}
编辑 - 已实施byPublishedAtComparator的代码：
private static final Comparator<Articles_Map> byPublishedAtComparator =
new Comparator<Articles_Map>() {
@Override
public int compare(Articles_Map o1, Articles_Map o2) {
if (o1.publishedAt == null || o2.publishedAt == null) {
return 0;
}
return o1.publishedAt.compareTo(o2.publishedAt);
}
};
答案 0 :(得分：4)
使用Collections.sort(List, Comparator)
Collections.sort(
myArticles_MapList, // your specific list to be sorted
new Comparator<Articles_Map>() {
public int compare(Articles_Map o1, Articles_Map o2) {
// Improve this to handle null publishedAt (make it early Paleozoic?)
return o1.getPublishedAt().compareTo(o2.getPublishedAt());
}
}
)
<击>
[被修改]
哈！但是ArrayAdapter已经有sort(Comparator)方法!!!
调用它：
add和addAll方法（可能更耗费CPU）。第二种方法可以这样：
public class NewsAdapter extends ArrayAdapter<Articles_Map> {
private static final Comparator<Articles_Map>
byPublishedAtComparetor = new Comparator<Articles_Map>() {
public int compare(Articles_Map o1, Articles_Map o2) {
// Improve this to handle null publishedAt
return o1.getPublishedAt().compareTo(o2.getPublishedAt());
}
}
;
Context mContext;
// snip...
public NewsAdapter(Context c, int resource, List<Articles_Map> articles) {
super(c, resource, articles);
this.sort(byPublishedAtComparetor);
this.mContext = c;
}
protected void doAdd(Articles_Map another) {
suoer.add(another);
}
// Override to maintain the order
void add(Articles_Map another) {
this.doAdd(another);
this.sort(byPublishedAtComparator);
}
// Overrides to maintain order and to avoid calling into
// individual add(...) method, which will cause unnecessary
// sorting after each element
@Override
public void addAll(Articles_Map... others) {
for(Articles_Map a : others) {
this.doAdd(a);
}
this.sort(byPublishedAtComparator);
}
@Override
public void addAll(Collection<Articles_Map> others) {
for(Articles_Map a : others) {
this.doAdd(a);
}
this.sort(byPublishedAtComparator);
}
@Override
public void insert(int i, Articles_Map article) {
// decline to insert it at any indicated position
// as it may break the order. Instead, treat it as any addition
// which will automatically result in a reordering
this.add(article);
}
// No override for remove - removing elements don't break
// the order