我有一个扩展pageradapter的滑动图像。起初它正在运作。但是当我打开新活动然后按下后退按钮，应用程序崩溃了，我有这个错误：
java.lang.IllegalStateException: The application's PagerAdapter changed the adapter's contents without calling PagerAdapter#notifyDataSetChanged! Expected adapter item count: 10, found: 0 Pager id: malate.denise.chelsie.igphthesisbfinal:id/pager Pager class: class android.support.v4.view.ViewPager Problematic adapter: class malate.denise.chelsie.igphthesisbfinal.SlidingImage_Adapter
这是我的SlidingImage_Adapter.class
public class SlidingImage_Adapter extends PagerAdapter {
private ArrayList<Pictures> IMAGES;
private LayoutInflater inflater;
private Context context;
public SlidingImage_Adapter(Context context,ArrayList<Pictures> IMAGES) {
this.context = context;
this.IMAGES=IMAGES;
inflater = LayoutInflater.from(context);
}
@Override
public void destroyItem(ViewGroup container, int position, Object object) {
container.removeView((View) object);
}
@Override
public int getCount() {
return IMAGES.size();
}
@Override
public Object instantiateItem(ViewGroup view, int position) {
View imageLayout = inflater.inflate(R.layout.slidingimage_layout, view, false);
assert imageLayout != null;
final ImageView imageView = (ImageView) imageLayout
.findViewById(R.id.image);
new DownloadImageTask(imageView).execute(IMAGES.get(position).getPhotopath());
// imageView.setImageResource(IMAGES.get(position));
view.addView(imageLayout, 0);
return imageLayout;
}
@Override
public boolean isViewFromObject(View view, Object object) {
return view.equals(object);
}
@Override
public void restoreState(Parcelable state, ClassLoader loader) {
notifyDataSetChanged();
}
@Override
public Parcelable saveState() {
return null;
}
和我的AttractionInfo.class
public class AttractionInfo extends ActionBarActivity implements View.OnClickListener {
TextToSpeech tts;
TextView nameofplace,location,exact_address,operatinghours,info;
String nameofplace_s,location_s,exact_address_s,operatinghours_s,info_s,latlang_s,path_s,category_s;
ImageView play,rate,addtoplan,map;
ArrayList<Pictures> records;
private static ViewPager mPager;
private static int currentPage = 0;
String line=null;
private static int NUM_PAGES = 0;
Toolbar toolbar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_attraction_info);
map = (ImageView)findViewById(R.id.map);
map.setOnClickListener(this);
records=new ArrayList<Pictures>();
nameofplace = (TextView) findViewById(R.id.nameofplace);
info = (TextView) findViewById(R.id.info);
exact_address = (TextView) findViewById(R.id.exact_address);
location = (TextView)findViewById(R.id.location);
operatinghours=(TextView)findViewById(R.id.operatinghours);
play = (ImageView) findViewById(R.id.play);
rate = (ImageView) findViewById(R.id.rate);
addtoplan = (ImageView)findViewById(R.id.addtoplan);
addtoplan.setOnClickListener(this);
Bundle extras = getIntent().getExtras();
play.setOnClickListener(this);
rate.setOnClickListener(this);
toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
getSupportActionBar().setDisplayHomeAsUpEnabled(true);
getSupportActionBar().setHomeButtonEnabled(true);
getSupportActionBar().setDisplayShowHomeEnabled(true);
getSupportActionBar().setHomeAsUpIndicator(R.drawable.abc_ic_ab_back_mtrl_am_alpha);
toolbar.setNavigationIcon(R.drawable.abc_ic_ab_back_mtrl_am_alpha);
toolbar.setNavigationOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
onBackPressed();
}
});
getSupportActionBar().setDisplayShowTitleEnabled(false);
tts = new TextToSpeech(AttractionInfo.this, new TextToSpeech.OnInitListener() {
@Override
public void onInit(int status) {
if (status != TextToSpeech.ERROR){
tts.setLanguage(Locale.ENGLISH);
}
}
});
if (extras != null) {
nameofplace_s = extras.getString("name");
nameofplace.setText(nameofplace_s);
info_s = extras.getString("description");
info.setText(info_s);
exact_address_s = extras.getString("exactaddress");
exact_address.setText(exact_address_s);
location_s = extras.getString("location");
location.setText(location_s);
operatinghours_s=extras.getString("operatinghours");
operatinghours.setText(operatinghours_s);
latlang_s = extras.getString("latlang");
path_s=extras.getString("path");
category_s = extras.getString("category");
}
}
public void onStart() {
super.onStart();
fetchphoto bt = new fetchphoto();
bt.execute();
}
@Override
protected void onPause() {
if (tts != null){
tts.stop();
tts.shutdown();
}
super.onPause();
}
@Override
public void onClick(View v) {
if (v == play) {
String speech1 = nameofplace.getText().toString();
String speech2 = info.getText().toString();
String speech = speech1 + "." + speech2;
tts.speak(speech, TextToSpeech.QUEUE_FLUSH, null);
} else if (v==rate){
Intent myIntent = new Intent(this, ListOfReviews.class);
myIntent.putExtra("placename", nameofplace_s);
myIntent.putExtra("category",category_s);
startActivity(myIntent);
}else if(v==addtoplan){
Intent myIntent = new Intent(this, AddPlan.class);
myIntent.putExtra("placename", nameofplace_s);
myIntent.putExtra("category",category_s);
startActivity(myIntent);
}else if (v == map){
Intent myIntent = new Intent(this, Map.class);
myIntent.putExtra("placename", nameofplace_s);
myIntent.putExtra("category",category_s);
myIntent.putExtra("latlang",latlang_s);
myIntent.putExtra("address",exact_address_s);
myIntent.putExtra("path",path_s);
startActivity(myIntent);
}
}
private void init() {
SlidingImage_Adapter adapter = new SlidingImage_Adapter(this,records);
for(int i=0;i<records.size();i++){
Pictures pics = records.get(i);
String pic = pics.getPhotopath();
adapter.notifyDataSetChanged();
}
mPager = (ViewPager) findViewById(R.id.pager);
mPager.setAdapter(adapter);
CirclePageIndicator indicator = (CirclePageIndicator)
findViewById(R.id.indicator);
indicator.setViewPager(mPager);
final float density = getResources().getDisplayMetrics().density;
indicator.setRadius(5 * density);
NUM_PAGES =records.size();
// Auto start of viewpager
final Handler handler = new Handler();
final Runnable Update = new Runnable() {
public void run() {
if (currentPage == NUM_PAGES) {
currentPage = 0;
}
mPager.setCurrentItem(currentPage++, true);
}
};
Timer swipeTimer = new Timer();
swipeTimer.schedule(new TimerTask() {
@Override
public void run() {
handler.post(Update);
}
},5000, 5000);
// Pager listener over indicator
indicator.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
@Override
public void onPageSelected(int position) {
currentPage = position;
}
@Override
public void onPageScrolled(int pos, float arg1, int arg2) {
}
@Override
public void onPageScrollStateChanged(int pos) {
}
});
}
private class fetchphoto extends AsyncTask<Void, Void, Void> {
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
protected void onPreExecute() {
super.onPreExecute();
}
protected Void doInBackground(Void... params) {
InputStream is = null;
String result = "";
nameValuePairs.add(new BasicNameValuePair("cityname", nameofplace_s));
try
{
records.clear();
HttpParams httpParams = new BasicHttpParams();
HttpClient httpclient = new DefaultHttpClient();
HttpPost httppost = new HttpPost("http://igph.esy.es/getphoto.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
Log.e("pass 1", "connection success ");
}
catch(Exception e)
{
Log.e("Fail 1", e.toString());
}
try
{
BufferedReader reader = new BufferedReader
(new InputStreamReader(is,"utf-8"),8);
StringBuilder sb = new StringBuilder();
while ((line = reader.readLine()) != null)
{
sb.append(line + "\n");
}
is.close();
result = sb.toString();
Log.e("pass 2", "connection success ");
}
catch(Exception e)
{
Log.e("Fail 2", e.toString());
}
//parse json data
try {
Log.i("tagconvertstr", "["+result+"]");
// Remove unexpected characters that might be added to beginning of the string
result = result.substring(result.indexOf(""));
JSONArray jArray = new JSONArray(result);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
Pictures p = new Pictures();
p.setPhotoname(json_data.getString("photo_name"));
p.setPlacename(json_data.getString("place_name"));
p.setCategory(json_data.getString("category"));
p.setPhotopath(json_data.getString("path"));
records.add(p);
}
} catch (Exception e) {
Log.e("ERROR", "Error pasting data " + e.toString());
}
return null;
}
protected void onPostExecute(Void result) {
// if (pd != null) pd.dismiss(); //close dialog
Log.e("size", records.size() + "");
init();
}
}
}
我已经解决了一些类似的问题，并了解到添加notifychanged可能会解决问题，但我不知道放在哪里。希望你能帮助我。谢谢