Android 更改ArrayAdapter的内容不会得到更新
清除或添加数据不会在自定义ArrayAdapter类中的addData方法中得到更新。发生了什么事?我还尝试过更新输入ArrayAdapter的列表,该列表也不会更改,两次适配器中的项目数量保持不变。请帮忙 类别:Android 更改ArrayAdapter的内容不会得到更新,android,android-arrayadapter,android-adapter,Android,Android Arrayadapter,Android Adapter,清除或添加数据不会在自定义ArrayAdapter类中的addData方法中得到更新。发生了什么事?我还尝试过更新输入ArrayAdapter的列表,该列表也不会更改,两次适配器中的项目数量保持不变。请帮忙 类别: package sukh.app.ireddit; import java.util.ArrayList; import java.util.Collection; import java.util.List; import android.app.Activity; impor
package sukh.app.ireddit;
import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AbsListView;
import android.widget.AbsListView.OnScrollListener;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;
/**
* While this looks like a lot of code, all this class
* actually does is load the posts in to the listview.
*
* @author Hathy
*/
public class PostsFragment extends Fragment{
ListView postsList;
PostAdapter adapter;
Handler handler;
Activity activity;
String subreddit;
List<Post> posts;
PostsHolder postsHolder;
public PostsFragment(){
handler=new Handler();
posts=new ArrayList<Post>();
activity=getActivity();
}
public static Fragment newInstance(String subreddit){
PostsFragment pf=new PostsFragment();
pf.subreddit=subreddit;
pf.postsHolder=new PostsHolder(pf.subreddit);
return pf;
}
@Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container,
Bundle savedInstanceState) {
View v=inflater.inflate(R.layout.posts
, container
, false);
postsList=(ListView)v.findViewById(R.id.posts_list);
return v;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
initialize();
}
private void initialize(){
// This should run only once for the fragment as the
// setRetainInstance(true) method has been called on
// this fragment
if(posts.size()==0){
// Must execute network tasks outside the UI
// thread. So create a new thread.
new Thread(){
public void run(){
posts.addAll(postsHolder.fetchPosts());
// UI elements should be accessed only in
// the primary thread, so we must use the
// handler here.
handler.post(new Runnable(){
public void run(){
createAdapter();
}
});
}
}.start();
}else{
createAdapter();
}
}
/**
* This method creates the adapter from the list of posts
* , and assigns it to the list.
*/
private void createAdapter(){
// Make sure this fragment is still a part of the activity.
if(getActivity()==null) return;
adapter=new PostAdapter(posts);
postsList.setAdapter(adapter);
Log.i("sukh", "setting adapter");
postsList.setOnScrollListener(adapter);
}
protected class PostAdapter extends ArrayAdapter<Post> implements OnScrollListener {
private int previousTotal = 0;
private boolean loading = true;
//PostAdapter _adapter = this;
public PostAdapter(List<Post> posts){
super(getActivity(), R.layout.post_item, posts);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if(convertView == null){
convertView = getActivity().getLayoutInflater().inflate(R.layout.post_item, null);
}
Post thePost = getItem(position);
TextView postTitleTextView = (TextView) convertView.findViewById(R.id.post_title);
postTitleTextView.setText(thePost.getTitle());
TextView postDetailsTextView = (TextView) convertView.findViewById(R.id.post_details);
postDetailsTextView.setText(thePost.getDetails());
TextView postScoreTextView = (TextView) convertView.findViewById(R.id.post_score);
postScoreTextView.setText(thePost.getScore());
return convertView;
}
private void addData() {
//final List<Post> newPosts = new ArrayList<Post>();
Log.i("update1", this.adapterToString());
new Thread(){
public void run(){
//neither of these following statements make a difference
//neither does posts.clear() or posts.addAll...
//adapter.addAll(postsHolder.fetchMorePosts());
adapter.clear();
}
};
Log.i("sukh", "executed scroll");
adapter.notifyDataSetChanged();
Log.i("update2", this.adapterToString());
}
private String adapterToString() {
StringBuilder sb = new StringBuilder();
int total = this.getCount();
sb.append("contents: ");
/*for (int i = 0; i < this.getCount(); i ++) {
sb.append(this.getItem(i).title + "/n");
}*/
//return sb.toString();
return sb.append(total).toString();
}
@Override
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
if (loading) {
if (totalItemCount > previousTotal) {
loading = false;
previousTotal = totalItemCount;
}
}
if (!loading &&
(firstVisibleItem + visibleItemCount + 1 >= totalItemCount)
) {
addData();
loading = true;
}
}
@Override
public void onScrollStateChanged(AbsListView view, int scrollState) {
}
}
}
包sukh.app.ireddit;
导入java.util.ArrayList;
导入java.util.Collection;
导入java.util.List;
导入android.app.Activity;
导入android.os.Bundle;
导入android.os.Handler;
导入android.support.v4.app.Fragment;
导入android.util.Log;
导入android.view.LayoutInflater;
导入android.view.view;
导入android.view.ViewGroup;
导入android.widget.AbsListView;
导入android.widget.AbsListView.OnScrollListener;
导入android.widget.ArrayAdapter;
导入android.widget.ListView;
导入android.widget.TextView;
/**
*虽然这看起来像是很多代码,但所有这些类
*实际上是将帖子加载到listview中。
*
*@作者哈蒂
*/
公共类PostsFragment扩展了片段{
列表视图后列表;
后适配器;
处理者;
活动;
字符串子reddit;
列出员额;
后支架后支架;
公共邮政部门(){
handler=新的handler();
posts=newarraylist();
activity=getActivity();
}
公共静态片段newInstance(字符串subreddit){
PostsFragment pf=新的PostsFragment();
pf.subreddit=subreddit;
pf.postsHolder=新的postsHolder(pf.subreddit);
返回pf;
}
@凌驾
创建视图上的公共视图(更平坦的充气机,
视图组容器,
Bundle savedInstanceState){
视图v=充气机。充气(右布局)柱
,货柜
,假);
postsList=(ListView)v.findViewById(R.id.posts\u list);
返回v;
}
@凌驾
创建时的公共void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setRetainInstance(真);
}
@凌驾
已创建ActivityState上的公共无效(Bundle savedInstanceState){
super.onActivityCreated(savedInstanceState);
初始化();
}
私有void初始化(){
//对于作为
//已调用setRetainInstance(true)方法
//这个片段
如果(posts.size()==0){
//必须在UI之外执行网络任务
//所以创建一个新的线程。
新线程(){
公开募捐{
posts.addAll(postsHolder.fetchPosts());
//UI元素只能在中访问
//主线程,因此我们必须使用
//我是handler。
handler.post(新的Runnable(){
公开募捐{
createAdapter();
}
});
}
}.start();
}否则{
createAdapter();
}
}
/**
*此方法从帖子列表中创建适配器
*,并将其指定给列表。
*/
私有void createAdapter(){
//确保此片段仍然是活动的一部分。
if(getActivity()==null)返回;
适配器=新的后适配器(posts);
postsList.setAdapter(适配器);
Log.i(“sukh”,“设置适配器”);
setOnScrollListener(适配器);
}
受保护类PostAdapter扩展ArrayAdapter实现OnScrollListener{
private int previousTotal=0;
私有布尔加载=真;
//PostAdapter\u适配器=此;
公共邮政适配器(列表邮件){
super(getActivity(),R.layout.post_项,posts);
}
@凌驾
公共视图getView(int位置、视图转换视图、视图组父视图){
if(convertView==null){
convertView=getActivity().GetLayoutFlater().充气(R.layout.post_项,空);
}
Post thePost=getItem(position);
TextView postTitleTextView=(TextView)convertView.findViewById(R.id.post_title);
postitletextview.setText(post.getTitle());
TextView postDetailsExtView=(TextView)convertView.findViewById(R.id.post_details);
postDetailsTextView.setText(post.getDetails());
TextView postScoreTextView=(TextView)convertView.findViewById(R.id.post_分数);
postScoreTextView.setText(post.getScore());
返回视图;
}
私有void addData(){
//最终列表newPosts=newarraylist();
Log.i(“update1”,this.adapterToString());
新线程(){
公开募捐{
//以下两种说法都没有区别
//posts.clear()或posts.addAll也不。。。
//adapter.addAll(postsHolder.fetchMorePosts());
适配器。清除();
}
};
Log.i(“sukh”,“已执行卷轴”);
adapter.notifyDataSetChanged();
Log.i(“update2”,this.adapterToString());
}
私有字符串适配器ostring(){
StringBuilder sb=新的StringBuilder();
int total=this.getCount();
某人附加(“内容:”);
/*for(int i=0;ipreviousTotal)
private class AddPostsTask extends AsyncTask<Void, Void, Void> {
@Override
protected Void doInBackground(Void... params) {
Log.i("update2", "start fetchMorePosts");
posts.addAll(postsHolder.fetchMorePosts());
Log.i("update2", "end fetchMorePosts");
return null;
}
@Override
protected void onPostExecute(Void result) {
Log.i("update2", "start adapterChange");
adapter.notifyDataSetChanged();
Log.i("update2", "start adapterChange");
super.onPostExecute(result);
}
}