问题
I have customized the code of EndlessAdapter in my app but one mistake done by me as this Endless Adapter always download data in the background instead it should download the same after user scroll downs the list and I unable to find the same mistake in our project. Due to this mistake my app sometimes returns OutOfMemoryException which is not acceptable.
Please suggest me any solution regarding the same.
Code: *MyEndlessAdapter:*
class DemoAdapterCat extends EndlessAdapter {
private RotateAnimation rotate=null;
ArrayList<String> tempListNamesCat = new ArrayList<String>();
ArrayList<String> tempListImagesCat = new ArrayList<String>();
ArrayList<String> tempListYearCat1 = new ArrayList<String>();
ArrayList<String> tempListYearCat2 = new ArrayList<String>();
ArrayList<String> tempListmpgCat1 = new ArrayList<String>();
ArrayList<String> tempListmpgCat2 = new ArrayList<String>();
ArrayList<String> tempListpriceCat1 = new ArrayList<String>();
ArrayList<String> tempListpriceCat2 = new ArrayList<String>();
ArrayList<String> tempListRatingCat1 = new ArrayList<String>();
ArrayList<String> tempListRatingCat2 = new ArrayList<String>();
DemoAdapterCat() {
super(new CategoryListLazyAdapter(ResearchList.this, countriesSubCat, imagesSubCat, YearSubCat1,YearSubCat2, mpgSubCat1,mpgSubCat2, priceSubCat1,priceSubCat2, ratingSubCat1, ratingSubCat2));
Utility util = new Utility();
util.setListViewHeightBasedOnChildren(lvCategory);
rotate=new RotateAnimation(0f, 360f, Animation.RELATIVE_TO_SELF,
0.5f, Animation.RELATIVE_TO_SELF,
0.5f);
rotate.setDuration(600);
rotate.setRepeatMode(Animation.RESTART);
rotate.setRepeatCount(Animation.INFINITE);
}
/*
@Override
public int getCount()
{
//return brandList.getDisplayNames().size();
return countriesSubCat.size();
}*/
@Override
protected View getPendingView(ViewGroup parent) {
row=getLayoutInflater().inflate(R.layout.categorylist, null);
child=row.findViewById(R.id.tv_CategoryItem_Name);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_MPG1);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_MPG2);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_Price1);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_Price2);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_Rating1);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_Rating2);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_Year1);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.tv_CategoryItem_Year2);
child.setVisibility(View.GONE);
/*child = row.findViewById(R.id.img_CategoryItem);
child.setVisibility(View.GONE);
child = row.findViewById(R.id.img_CategoryItem_Arrow);
child.setVisibility(View.GONE);*/
/*child = row.findViewById(R.id.linear_main_MPG);
child.setVisibility(View.GONE);*/
child=row.findViewById(R.id.throbber);
child.setVisibility(View.VISIBLE);
child.startAnimation(rotate);
return(row);
}
@Override
protected boolean cacheInBackground() {
SystemClock.sleep(10000);
tempListNamesCat.clear();
tempListImagesCat.clear();
tempListmpgCat1.clear();
tempListmpgCat2.clear();
tempListpriceCat1.clear();
tempListpriceCat2.clear();
tempListYearCat1.clear();
tempListYearCat2.clear();
tempListRatingCat1.clear();
tempListRatingCat2.clear();
int lastOffset = getLastOffset();
if(lastOffset < LIST_SIZE){
int limit = lastOffset + BATCH_SIZE;
for(int i=(lastOffset+1); (i<=limit && i<LIST_SIZE); i++){
tempListNamesCat.add(coll.getDisplayNames().get(i));
tempListImagesCat.add(coll.getImages().get(i));
tempListmpgCat1.add(coll.getMpg().get(i));
tempListmpgCat2.add(coll.getMpg().get(i+1));
tempListpriceCat1.add(coll.getPrice().get(i));
tempListpriceCat2.add(coll.getPrice().get(i+1));
tempListRatingCat1.add(coll.getRating().get(i));
tempListRatingCat2.add(coll.getRating().get(i+1));
tempListYearCat1.add(coll.getYears().get(i));
tempListYearCat2.add(coll.getYears().get(i+1));
}
setLastOffset(limit);
if(limit<LIST_SIZE){
//return true;
return(getWrappedAdapter().getCount()<coll.getDisplayNames().size());
} else {
return false;
}
} else {
return false;
}
}
@Override
protected void appendCachedData() {
@SuppressWarnings("unchecked")
//Activity activity = this;
//ArrayAdapter<String> arrAdapterNew = (ArrayAdapter<String>)getWrappedAdapter();
CategoryListLazyAdapter arrAdapterNewCategory = (CategoryListLazyAdapter)getWrappedAdapter();
//int listLen = tempList.size();
// int listLen = tempListNames.size();
countriesSubCat.addAll(tempListNamesCat);
imagesSubCat.addAll(tempListImagesCat);
mpgSubCat1.addAll(tempListmpgCat1);
mpgSubCat2.addAll(tempListmpgCat2);
priceSubCat1.addAll(tempListpriceCat1);
priceSubCat2.addAll(tempListpriceCat2);
ratingSubCat1.addAll(tempListRatingCat1);
ratingSubCat2.addAll(tempListRatingCat2);
YearSubCat1.addAll(tempListYearCat1);
YearSubCat2.addAll(tempListYearCat2);
arrAdapterNewCategory.notifyDataSetChanged();
Utility util = new Utility();
util.setListViewHeightBasedOnChildren(lvCategory);
/* for(int i=0; i<listLen; i++){
// arrAdapterNew.add(tempList.get(i));
}*/
}
}
Set Demoadapter to the list:
public void setValuesInCategoryChildSortByAZ(String url,final String filter, final String from, final String to)
{
if(isOnline())
{
final ProgressDialog dialog = ProgressDialog.show(
ResearchList.this, "Research List ",
"Please wait... ", true);
final Handler handler = new Handler() {
public void handleMessage(Message msg) {
// System.out.println("The id after Save:"+id.get(0).toString());
// catagory.addAll(keyword_vector1);
linear_Category_Child.setVisibility(View.GONE);
linear_Category_Child_Child.setVisibility(View.VISIBLE);
//tv_Child_Header.setText("Volvo");
/*adapter = new CategoryListLazyAdapter(
ResearchList.this);
lvCategory.setAdapter(adapter);*/
demoAdapterCat.notifyDataSetChanged();
Utility util = new Utility();
util.setListViewHeightBasedOnChildren(lvCategory);
dialog.dismiss();
}
};
final Thread checkUpdate = new Thread() {
public void run() {
try {
String sortEncode = URLEncoder.encode("alpha");
String filterEncode = URLEncoder.encode(filter);
String clientEncode = URLEncoder.encode("10030812");
String fromEncode = URLEncoder.encode(from);
String toEncode = URLEncoder.encode(to);
String catUrl = "/v1/vehicles/get-make-models.json?sort="+sortEncode+"&filter="+filterEncode+"&client-id="+clientEncode+"&from="+fromEncode;
genSig = new GetSignature(catUrl, "acura");
try {
signature = genSig.getUrlFromString();
} catch (InvalidKeyException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (NoSuchAlgorithmException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
// jsonString =
// getJsonSring("http://api.highgearmedia.com/v1/vehicles/get-models.json?make=acura&client-id=10030812&signature=LWQbdAlJVxlXZ1VO2mfqAA==");
//String signatureEncode = URLEncoder.encode(signature);
String urlEncode = URLEncoder.encode(catUrl+"&signature="+signature);
jsonString = getJsonSring("http://apibeta.highgearmedia.com"+catUrl+"&signature="+signature);
System.out.println("The json category:===>"+jsonString);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (URISyntaxException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
JsonParse json = new JsonParse(jsonString);
json.parseCat();
handler.sendEmptyMessage(0);
}
};
checkUpdate.start();
}else
{
AlertDialog.Builder builder = new Builder(ResearchList.this);
builder.setTitle("Attention!");
builder.setMessage("Network Connection unavailable.");
builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
}
});
builder.create().show();
}
}
Thanks in advance.
回答1:
I unable to find the same mistake in our project
The EndlessAdapter sample app is here: https://github.com/commonsguy/cwac-endless/tree/master/demo.
If you look at that sample app, you will notice that it does not fork any threads.
If you read the EndlessAdapter documentation, you will see:
Your EndlessAdapter subclass also needs to implement cacheInBackground(). This method will be called from a background thread, and it needs to download more data that will eventually be added to the ListAdapter you used in the constructor. While the demo application simply sleeps for 10 seconds, a real application might make a Web service call or otherwise load in more data.
Since this method is called on a background thread, you do not need to fork your own thread. However, at the same time, do not try to update the UI directly.
So, change your project to not fork your own thread, but instead do your work in cacheInBackground() to retrieve and add the next batch of data.
If that approach does not fit the way your app needs to run, that is fine, but you may have difficulty in using EndlessAdapter.
来源：https://stackoverflow.com/questions/11022562/endless-adapter-always-running-to-download-data-in-background