您好我必须在Android应用程序中使用xml解析来开发带有更多按钮的listview。
我遇到了一些问题。
我的xml Feed为空意味着如何隐藏最后一页上的加载更多按钮。
我在这里使用了以下代码。
public class CustomizedListView extends Activity {
// All static variables
private String URL = "http://dev.mmm.com/xctesting/xcart444pro/retrieve.php?page=1";
// XML node keys
static final String KEY_SONG = "Order";
static final String KEY_TITLE = "orderid";
static final String KEY_DATE = "date";
static final String KEY_ARTIST = "payment_method";
int current_page = 1;
ListView lv;
LazyAdapter adapter;
ProgressDialog pDialog;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
lv = (ListView) findViewById(R.id.list);
ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL); // getting XML from URL
Document doc = parser.getDomElement(xml); // getting DOM element
NodeList nl = doc.getElementsByTagName(KEY_SONG);
// looping through all song nodes <song>
for (int i = 0; i < nl.getLength(); i++) {
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
Element e = (Element) nl.item(i);
// adding each child node to HashMap key => value
map.put(KEY_ID, parser.getValue(e, KEY_ID));
map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST));
songsList.add(map);
}
Button btnLoadMore = new Button(this);
btnLoadMore.setText("Load More");
btnLoadMore.setBackgroundResource(R.drawable.lgnbttn);
// Adding Load More button to lisview at bottom
lv.addFooterView(btnLoadMore);
// Getting adapter
adapter = new LazyAdapter(this, songsList);
lv.setAdapter(adapter);
btnLoadMore.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Starting a new async task
new loadMoreListView().execute();
}
});
}
private class loadMoreListView extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
// Showing progress dialog before sending http request
pDialog = new ProgressDialog(
CustomizedListView.this);
pDialog.setMessage("Please wait..");
//pDialog.setIndeterminateDrawable(getResources().getDrawable(R.drawable.my_progress_indeterminate));
pDialog.setIndeterminate(true);
pDialog.setCancelable(false);
pDialog.show();
pDialog.setContentView(R.layout.custom_dialog);
}
protected Void doInBackground(Void... unused) {
current_page += 1;
// Next page request
URL = "http://dev.mmm.com/xctesting/xcart444pro/retrieve.php?page=" + current_page;
ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
XMLParser parser = new XMLParser();
String xml = parser.getXmlFromUrl(URL); // getting XML from URL
Document doc = parser.getDomElement(xml); // getting DOM element
NodeList nl = doc.getElementsByTagName(KEY_SONG);
NodeList nl = doc.getElementsByTagName(KEY_SONG);
if (nl.getLength() == 0)
{
btnLoadMore.setVisibility(View.GONE);
pDialog.dismiss();
}
else
// looping through all item nodes <item>
for (int i = 0; i < nl.getLength(); i++) {
// creating new HashMap
HashMap<String, String> map = new HashMap<String, String>();
Element e = (Element) nl.item(i);
// adding each child node to HashMap key => value
map.put(KEY_ID, parser.getValue(e, KEY_ID));
map.put(KEY_TITLE, parser.getValue(e, KEY_TITLE));
map.put(KEY_ARTIST, parser.getValue(e, KEY_ARTIST));
songsList.add(map);
}
// get listview current position - used to maintain scroll position
int currentPosition = lv.getFirstVisiblePosition();
// Appending new data to menuItems ArrayList
adapter = new LazyAdapter(
CustomizedListView.this,
songsList);
lv.setAdapter(adapter);
lv.setSelectionFromTop(currentPosition + 1, 0);
}
});
return (null);
}
protected void onPostExecute(Void unused) {
// closing progress dialog
pDialog.dismiss();
}
}
}
修改
这里我必须运行应用程序意味着列表视图显示在perpage 4 items.my最后一页有1项。请参阅此屏幕截图：lastpage 在最后一页我必须点击加载更多按钮意味着必须进入下一个活动并成功隐藏空白页面上的按钮 ..请参阅此屏幕截图：empty page-so hide the button
我必须检查空页的条件：
if (nl.getLength() == 0)
{
btnLoadMore.setVisibility(View.GONE);
pDialog.dismiss();
}
我如何在最后一页写下条件?????请帮助我
这里我希望o / p隐藏最后一页的按钮。
请帮助我。我可以检查一下条件。以编程方式给我一些代码。
答案 0 :(得分：1)
我使用这种方式实现了更多的负载我不使用页脚视图
public boolean mHasLoadMore = false;
class MyAdapter extends ArrayAdapter implements OnItemClickListener{
public MyAdapter(Context context, int textViewResourceId) {
super(context, textViewResourceId);
// TODO Auto-generated constructor stub
}
public int getTotal(){
return super.getCount();
}
@Override
public int getCount() {
if(super.getCount()>0)
return super.getCount()+1;
else
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
if( getTotal() == (position+1) && mHasLoadMore ){
TextView loadMoreView = new TextView(getContext());
loadMoreView.setText("Load More");
return loadMoreView;
}
else {
View theView = new View(getContext());
// inflate & add what you need for item view here you can modify it to reuse convertView also
return theView;
}
}
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int position,
long id) {
if( getTotal() == (position+1) && mHasLoadMore ){
// load more button clicked do handling for load more launch async
//task to do load more after that if found 0 result change mHasLoadMore to false
//& call notifydatadetchanged
}
else
{
// handle item click here
}
}
}
将此类适配器用于listview＆amp;在加载数据时首次设置mHasLoadMore的值叫notifydatasetchanged
答案 1 :(得分：1)
首先，你为什么在AsyncTaks中使用runOnUiThread？这不应该是必要的。必须在后台运行的代码，在doInBackground方法中就足够了。
此外，您可以使用AsyncTask的第三个参数类型将te doInBackground的结果返回到onPostExecute。然后根据结果，您可以更改按钮的可见性。
为此，对Button的引用（在您的情况下为btnLoadMore）应该是一个实例变量，因此应该在类中定义，而不是在onCreate方法中定义。否则，无法从此方法外部访问它。
我认为当Feed为空时，nodelist将为空？然后它看起来像这样：
public class CustomizedListView extends Activity {
private Button btnLoadMore;
public void onCreate(){
btnLoadMore = new Button(this);
<do stuff>
btnLoadMore.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View arg0) {
// Starting a new async task
new LoadMoreListView().execute();
}
});
new LoadMoreListView().execute();// execute the AsyncTask once in the onCreate, so you don't have to duplicate the code here to load the listview.
}
private class LoadMoreListView extends AsyncTask<Void, Void, Boolean> {
@Override
protected void onPreExecute() {
< Show dialog>;
}
@Override
protected Void doInBackground(Void... unused) {
Boolean listIsEmpty;
< Page request>;
< Retrieve element list>;
< If element list size == 0, listIsEmpty = true; return listIsEmpty>;
< Process elements, fill list etc.>;
< End of doInBackground, listIsEmpty = false; return listIsEmpty>;
}
@Override
protected void onPostExecute(Boolean listIsEmpty) {
< If listIsEmpty == true -> btnLoadMore.setVisibility(View.GONE);>
< Close dialog>
}
}
}
}