Java 如何多次使用同一片段?
我正在创建一个应用程序,它从一个网站的XML文件中获取数据,并将这些数据传递给一个片段 我使用的是一个操作栏,我有3个选项卡,还有一个ViewPager。 片段包含一个ListView,我使用Bundle传递数据,我可以正确地从片段中获取传递的数据Java 如何多次使用同一片段?,java,android,xml,listview,android-fragments,Java,Android,Xml,Listview,Android Fragments,我正在创建一个应用程序,它从一个网站的XML文件中获取数据,并将这些数据传递给一个片段 我使用的是一个操作栏,我有3个选项卡,还有一个ViewPager。 片段包含一个ListView,我使用Bundle传递数据,我可以正确地从片段中获取传递的数据 public Fragment getItem(int i){ switch(i){ case 0: Bundle b1= new Bundle(); b1.putString("cat", "artufonews
public Fragment getItem(int i){
switch(i){
case 0:
Bundle b1= new Bundle();
b1.putString("cat", "artufonews");
Fragment f1 = new LoadFrag();
f1.setArguments(b1);
return f1;
case 1:
Bundle b2 = new Bundle();
b2.putString("cat", "artufo");
Fragment f2 = new LoadFrag();
f2.setArguments(b2);
return f2;
case 2:
Bundle b3 = new Bundle();
b3.putString("cat", "artmyst");
Fragment f3 = new LoadFrag();
f3.setArguments(b3);
return f3;
default :
return new LoadMee();
}
}
LoadFrag是我拥有的片段。我可以正确地传递数据,但是当我尝试使用mPager.getAdapter.notifyDataSetChanged更新listview时,无论我做什么,这3个选项卡都会显示相同的列表
下面的代码是片段代码:
public static class LoadFrag extends Fragment{
String cat;
boolean kl = false;
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
//new TestAsync().execute();
View rootView = inflater.inflate(R.layout.listfrage, container, false);
ListView viewer;
String[] hell = (String[])list.toArray(new String[list.size()]);
final String[] tots = (String[])links.toArray(new String[links.size()]);
cat = getArguments().getString("cat");
CustomLister lister = new CustomLister(getActivity(), hell, bmps);
viewer = (ListView)rootView.findViewById(R.id.lister);
viewer.setAdapter(lister);
viewer.setOnItemClickListener(new AdapterView.OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id){
Toast.makeText(getActivity(), "You clicked: item " + tots[position], Toast.LENGTH_SHORT).show();;
Intent i = new Intent(getActivity(), Starter.class);
i.putExtra("link", tots[position]);
startActivity(i);
}
});
return rootView;
}
@Override
public void setMenuVisibility(final boolean visible) {
super.setMenuVisibility(visible);
if (visible && kl == false) {
getActivity().setTitle(cat);
new TestAsync().execute();
kl = true;
}
}
class TestAsync extends AsyncTask<Void, Integer, String>
{
String TAG = getClass().getSimpleName();
ProgressDialog dialog;
protected void onPreExecute (){
Log.d(TAG + " PreExceute","On pre Exceute......");
dialog = new ProgressDialog(getActivity());
dialog.setMessage("Loading content..");
dialog.setIndeterminate(true);
dialog.setCancelable(false);
dialog.show();
}
protected String doInBackground(Void...arg0) {
Log.d(TAG + " DoINBackGround","On doInBackground...");
tasker(cat);
return "You are at PostExecute";
}
protected void onProgressUpdate(Integer...a){
Log.d(TAG + " onProgressUpdate", "You are in progress update ... " + a[0]);
}
protected void onPostExecute(String result) {
Log.d(TAG + " onPostExecute", "" + result);
dialog.dismiss();
mPager.getAdapter().notifyDataSetChanged();
}
public void tasker(String tag)
{
try{
URL url = new URL("http://www.skyovnis.com/test.xml");
DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
DocumentBuilder db = dbf.newDocumentBuilder();
Document doc = db.parse(new InputSource(url.openStream()));
doc.getDocumentElement().normalize();
NodeList nodeList = doc.getElementsByTagName(tag);
for (int i = 0; i < nodeList.getLength(); i++) {
Node node = nodeList.item(i);
Element fstElmnt = (Element) node;
NodeList nameList = fstElmnt.getElementsByTagName("title");
Element nameElement = (Element) nameList.item(0);
nameList = nameElement.getChildNodes();
list.add(((Node)nameList.item(0)).getNodeValue());
NodeList websiteList = fstElmnt.getElementsByTagName("link");
Element websiteElement = (Element) websiteList.item(0);
websiteList = websiteElement.getChildNodes();
links.add(((Node) websiteList.item(0)).getNodeValue());
NodeList imgLinks = fstElmnt.getElementsByTagName("linkp");
Element imgElement = (Element) imgLinks.item(0);
imgLinks = imgElement.getChildNodes();
linksp.add(((Node) imgLinks.item(0)).getNodeValue());
}
bmps = new Bitmap[linksp.size()];
String[] imgs = (String[])linksp.toArray(new String[linksp.size()]);
for(int i = 0; i < linksp.size(); i++){
URL urls = new URL(imgs[i]);
bmps[i] = BitmapFactory.decodeStream(urls.openConnection().getInputStream());
}
org.jsoup.nodes.Document docs = Jsoup.connect("http://www.skyovnis.com/arecibo-message/").get();
org.jsoup.select.Elements newsHeadlines = docs.select("div.entry-content p");
for(org.jsoup.nodes.Element ele : newsHeadlines){
hello = hello + ele.text();
}
}
catch(Exception e){
System.out.println(e);
}
}
}
}
我的CustomLister课程
package com.ovnis.skybeings;
import java.net.URL;
import java.util.List;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;
public class CustomLister extends ArrayAdapter<String>{
private final Activity context;
private final String[] web;
private final Bitmap[] bmps;
public CustomLister(Activity context, String[] web, Bitmap[] bmps){
super(context, R.layout.list_compon, web);
this.context = context;
this.web = web;
this.bmps = bmps;
}
@Override
public View getView(int pos, View view, ViewGroup parent){
LayoutInflater inflater = context.getLayoutInflater();
View rowView = inflater.inflate(R.layout.list_compon, null, true);
TextView txtTitle = (TextView)rowView.findViewById(R.id.txt);
ImageView imageView = (ImageView)rowView.findViewById(R.id.img);
txtTitle.setText(web[pos]);
imageView.setImageBitmap(bmps[pos]);
return rowView;
}
}
您需要捕获以前发送的包。执行以下操作可能可以解决您的问题:
@Override
public void onActivityCreated(@Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
Bundle bundle = this.getArguments();
if (bundle != null) {
yourStringData= bundle.getString("cat", "DEFAULT_VALUE");
setupYourUIWithTheData(yourStringData);
} else {
Log.d(TAG, "bundle null");
}
}
private void setupYourUIWithTheData(String yourData) {
// Process the received data here.
// Show all related with the data here.
}
--更新--
要向片段传递值,推荐的方法是向片段添加静态方法,如:
然后,您可以简单地称之为:
LoadFrag.newInstance("your_category");
出了什么问题:
在MyAdapter的getItemPosition方法中,返回位置\u NONE。这意味着无论何时调用MyAdapternotifyDataSetChanged,都将在ViewPager中重新创建所有片段。您可以通过在LoadFragonCreateView中添加日志消息来验证此行为
请注意,每次异步任务完成后都会调用onCreateView。在AsyncTask完成并显示ListView的初始状态后,您基本上是在重新创建LoadFrag
如何修复它
在CustomLister中添加方法以更新数据
public class CustomLister extends ArrayAdapter<String>{
...
public void updateData(String[] newWeb, Bitmap[] newBmps){
web = newWeb;
bmps = newBmps;
notifyDataSetChanged();
}
...
}
在AsyncTask中,获取CustomLister的引用并使用新的数据集调用lister.updateData,而不是调用mPager.getAdapter.notifyDataSetChanged,这是因为您没有捕获以前发送的包。@。你能看到我的setMenuVisibility代码吗?每当我选择选项卡时,它都会将我的应用程序标题设置为传递给片段的字符串。它也正常工作,它也改变了我的标题。唯一的问题是显示给我的所有标签都是相同的列表好吧,我错了。我没有看到您的cat=getArguments.getStringcat;先前可能是因为您没有设置CustomLister lister=new CustomListTargetActivity,hell,bmps;到您的类别?您好,可以显示您的ViewPager适配器的代码吗?您仍然没有显示您的ViewPager适配器代码。我需要看看你的MyAdapter类。您正在调用mPager.getAdapter.notifyDataSetChanged;通知MyAdapter数据集已更改。仅通知MyAdapter不会神奇地改变您的视图。我需要知道您是如何实现MyAdapter的。我现在就尝试一下。我不知道重构片段以使用newInstance如何帮助解决这个问题。@Egor:嗯,在我添加答案之前,我错过了阅读整个代码的机会。认为op还没有实现阅读包。我为此道歉。不,它也不起作用。我的listview在3个选项卡中仍然有相同的项@ישואבאותך我尝试了你编辑的答案,而不是works mate。这也没有解决我的问题,谢谢你的更正。
public static LoadFrag newInstance(String category) {
LoadFrag fragment = new LoadFrag ();
Bundle bundle = new Bundle();
bundle.putString("cat", category);
fragment.setArguments(bundle);
return fragment;
}
LoadFrag.newInstance("your_category");
public static class LoadFrag extends Fragment{
...
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
// Add a Log message here to verify
Log.d("LoadFrag", "In onCreateView");
...
}
...
}
public class CustomLister extends ArrayAdapter<String>{
...
public void updateData(String[] newWeb, Bitmap[] newBmps){
web = newWeb;
bmps = newBmps;
notifyDataSetChanged();
}
...
}