解析XML並填充自定義ListView； 哪里都應該做？
[英]Parsing XML and populating custom ListView; where should everything be done?
問題描述
我目前正在開發一個Android應用，該應用可解析一些XML並將其放入ListView。 我使用了將StringBuilder對象放入TextView的方法，但是對適配器進行編碼后，無法填充ListView。
我正在按照本教程進行操作： 將ArrayAdapter與ListView一起使用 ，此刻我的代碼緊隨其后，但輸出卻空白。
我在想，也許由於本教程中未提及它，所以應該在MainActivity之外的其他地方對適配器或其他東西進行編碼？
activity_main.xml中
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/mainList" />
</RelativeLayout>
list_view.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="?android:attr/listPreferredItemHeight"
android:padding="6dip" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:id="@+id/titleView"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceSmall"
android:id="@+id/summaryView"
android:layout_below="@+id/titleView"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceMedium"
android:id="@+id/priceView"
android:layout_centerVertical="true"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
Entry.java
public class Entry
{
public String title;
public String summary;
public String price;
public Entry (String title, String summary, String price)
{
this.title = title;
this.summary = summary;
this.price = price;
}
}
MainActivity.java
public class MainActivity extends AppCompatActivity
{
TextView xmlTV;
ListView listView;
ArrayList<Entry> entries = new ArrayList<Entry>();
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.mainList);
ArrayList<Entry> arrayOfEntries = new ArrayList<Entry>();
EntryAdapter adapter = new EntryAdapter(this, arrayOfEntries);
ListView listView = (ListView) findViewById(R.id.mainList);
listView.setAdapter(adapter);
new PerformAsyncTask().execute();
Log.d("PerformAsyncTask", "execute asynctask");
adapter.addAll(entries);
Log.d("PerformAsyncTask", "Add all entries to adapter");
}
private class PerformAsyncTask extends AsyncTask<Void, Void, Void>
{
@Override
protected void onPreExecute()
{
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params)
{
String newTitle = null;
String newSummary = null;
String newPrice = null;
try
{
URL input = new URL("https://itunes.apple.com/us/rss/toptvepisodes/limit=25/genre=4008/xml");
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
factory.setNamespaceAware(true);
XmlPullParser xpp = factory.newPullParser();
xpp.setInput(getInputStream(input), "UTF_8");
int eventType = xpp.getEventType();
while (eventType != XmlPullParser.END_DOCUMENT)
{
if (eventType == XmlPullParser.START_TAG)
{
if (xpp.getName().equalsIgnoreCase("title"))
{
newTitle = xpp.nextText();
Log.d("PerformAsyncTask", "Add title");
}
if (xpp.getName().equalsIgnoreCase("summary"))
{
newSummary = xpp.nextText();
Log.d("PerformAsyncTask", "Add summary");
}
if (xpp.getName().equalsIgnoreCase("price"))
{
newPrice = xpp.nextText();
Log.d("PerformAsyncTask", "Add price");
Entry newEntry = new Entry(newTitle, newSummary, newPrice);
entries.add(newEntry);
Log.d("PerformAsyncTask", "Entry added");
}
}
eventType = xpp.next();
Log.d("PerformAsyncTask", "Skip to next item");
}
}
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_SHORT);
}
return null;
}
}
public class EntryAdapter extends ArrayAdapter<Entry>
{
public EntryAdapter (Context context, ArrayList<Entry> entries)
{
super(context, 0, entries);
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
Entry entry = getItem(position);
if (convertView == null)
{
convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_view, parent, false);
}
TextView tvTitle = (TextView) convertView.findViewById(R.id.titleView);
TextView tvSummary = (TextView) convertView.findViewById(R.id.summaryView);
TextView tvPrice = (TextView) convertView.findViewById(R.id.priceView);
tvTitle.setText(entry.title);
tvSummary.setText(entry.summary);
tvPrice.setText(entry.price);
return convertView;
}
}
public InputStream getInputStream(URL url)
{
try
{
return url.openConnection().getInputStream();
}
catch (IOException e)
{
Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_SHORT);
return null;
}
}
}
2 個解決方案
解決方案1
0 2017-02-14 07:27:21
您忘記將列表添加到適配器。 在列表的AsyncTask doInBackground（）結尾：
private class PerformAsyncTask extends AsyncTask<Void, Void, Void> {
...
@Override
protected Void doInBackground(Void... params) {
...
adapter.addAll(entries);
}
}
或者您可以使用adapter.notifyDataSetChanged(); 也。
解決方案2
0 2017-02-14 07:45:23
您可以像這樣更改代碼
public class MainActivity extends AppCompatActivity
{
TextView xmlTV;
ListView listView;
ArrayList<Entry> entries = new ArrayList<Entry>();
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listView = (ListView) findViewById(R.id.mainList);
//ArrayList<Entry> arrayOfEntries = new ArrayList<Entry>();
EntryAdapter adapter = new EntryAdapter(this, entries );
ListView listView = (ListView) findViewById(R.id.mainList);
listView.setAdapter(adapter);
new PerformAsyncTask().execute();
Log.d("PerformAsyncTask", "execute asynctask");
//adapter.addAll(entries);
Log.d("PerformAsyncTask", "Add all entries to adapter");
}
private class PerformAsyncTask extends AsyncTask<Void, Void, Void>
{
@Override
protected void onPreExecute()
{
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... params)
{
String newTitle = null;
String newSummary = null;
String newPrice = null;
try
{
URL input = new URL("https://itunes.apple.com/us/rss/toptvepisodes/limit=25/genre=4008/xml");
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
factory.setNamespaceAware(true);
XmlPullParser xpp = factory.newPullParser();
xpp.setInput(getInputStream(input), "UTF_8");
int eventType = xpp.getEventType();
while (eventType != XmlPullParser.END_DOCUMENT)
{
if (eventType == XmlPullParser.START_TAG)
{
if (xpp.getName().equalsIgnoreCase("title"))
{
newTitle = xpp.nextText();
Log.d("PerformAsyncTask", "Add title");
}
if (xpp.getName().equalsIgnoreCase("summary"))
{
newSummary = xpp.nextText();
Log.d("PerformAsyncTask", "Add summary");
}
if (xpp.getName().equalsIgnoreCase("price"))
{
newPrice = xpp.nextText();
Log.d("PerformAsyncTask", "Add price");
Entry newEntry = new Entry(newTitle, newSummary, newPrice);
entries.add(newEntry);
Log.d("PerformAsyncTask", "Entry added");
}
}
eventType = xpp.next();
Log.d("PerformAsyncTask", "Skip to next item");
}
}
catch (Exception e)
{
e.printStackTrace();
Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_SHORT);
}
return null;
}
@Override
protected void onPostExecute()
{
super.onPostExecute();
adapter.notifyDataSetChanged();
}
}
public class EntryAdapter extends ArrayAdapter<Entry>
{
public EntryAdapter (Context context, ArrayList<Entry> entries)
{
super(context, 0, entries);
}
@Override
public View getView(int position, View convertView, ViewGroup parent)
{
Entry entry = getItem(position);
if (convertView == null)
{
convertView = LayoutInflater.from(getContext()).inflate(R.layout.list_view, parent, false);
}
TextView tvTitle = (TextView) convertView.findViewById(R.id.titleView);
TextView tvSummary = (TextView) convertView.findViewById(R.id.summaryView);
TextView tvPrice = (TextView) convertView.findViewById(R.id.priceView);
tvTitle.setText(entry.title);
tvSummary.setText(entry.summary);
tvPrice.setText(entry.price);
return convertView;
}
}
public InputStream getInputStream(URL url)
{
try
{
return url.openConnection().getInputStream();
}
catch (IOException e)
{
Toast.makeText(MainActivity.this, e.toString(), Toast.LENGTH_SHORT);
return null;
}
}
}
解析XML並填充到Map中
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