问题
While developing a Gems app with the help of Fragments,logcat error occurred at runtime.
LogCat:
E/AndroidRuntime(667): FATAL EXCEPTION: main
E/AndroidRuntime(667): java.lang.NullPointerException
E/AndroidRuntime(667): at com.sit.gems.frgment.HomeBaseFragment.onMoreFragmentOptionSelected(HomeBaseFragment.java:345)
E/AndroidRuntime(667): at com.sit.gems.activity.HomeActivity.onMoreFragmentOptionSelected(HomeActivity.java:80)
E/AndroidRuntime(667): at com.sit.gems.frgment.MoreFragment$1.onItemClick(MoreFragment.java:44)
E/AndroidRuntime(667): at android.widget.AdapterView.performItemClick(AdapterView.java:292)
E/AndroidRuntime(667): at android.widget.AbsListView.performItemClick(AbsListView.java:1058)
E/AndroidRuntime(667): at android.widget.AbsListView$PerformClick.run(AbsListView.java:2514)
E/AndroidRuntime(667): at android.widget.AbsListView$1.run(AbsListView.java:3168)
E/AndroidRuntime(667): at android.os.Handler.handleCallback(Handler.java:605)
E/AndroidRuntime(667): at android.os.Handler.dispatchMessage(Handler.java:92)
E/AndroidRuntime(667): at android.os.Looper.loop(Looper.java:137)
E/AndroidRuntime(667): at android.app.ActivityThread.main(ActivityThread.java:4340)
E/AndroidRuntime(667): at java.lang.reflect.Method.invokeNative(Native Method)
E/AndroidRuntime(667): at java.lang.reflect.Method.invoke(Method.java:511)
E/AndroidRuntime(667): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
E/AndroidRuntime(667): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
E/AndroidRuntime(667): at dalvik.system.NativeStart.main(Native Method)
HomeBaseFragment.java:
package com.sit.gems.frgment;
public class HomeBaseFragment extends BaseFragment implements OnTabChangeListener {
private View mRoot;
private TabHost mTabHost;
private int mCurrentTab;
private AudioFragment mAudioFragment;
private LiveStreamFragment liveStreamFragment;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
new GetLiveStreamVideoTask(getActivity()).execute();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
mRoot = inflater.inflate(R.layout.layout_home, null);
mTabHost = (TabHost) mRoot.findViewById(android.R.id.tabhost);
mAudioFragment = new AudioFragment();
liveStreamFragment = new LiveStreamFragment();
setupTabs();
return mRoot;
}
@Override
public void onActivityCreated(Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
updateTab("Home", R.id.tab_home);
}
public class GetLiveStreamVideoTask extends CustomAsyncTask {
private String responseString;
public GetLiveStreamVideoTask(Activity activity) {
super(activity);
enableLoadingDialog(false);
}
@Override
public void doTask() throws Exception {
responseString = APIServiceHandler
.getData("http://splendor.pro/gemapp/api/livestream.php");
}
@Override
public void doFinish() {
if (responseString != null) {
try {
JSONObject resposeJsonObject = new JSONObject(
responseString);
int statusCode = resposeJsonObject.optInt("statusCode", 0);
if (statusCode == 200) {
JSONArray jsonArray = resposeJsonObject
.getJSONArray("videos");
List<Video> videos = new ArrayList<Video>();
for (int i = 0; i < jsonArray.length(); i++) {
Video video = new Video(jsonArray.getJSONObject(i));
videos.add(video);
}
if(videos.size()>0){
Video video=videos.get(0);
appData.setLiveStreamVideo(video);
}
}
} catch (Exception e) {
}
}
}
}
private void setupTabs() {
mTabHost.setup();
mTabHost.addTab(newTab(getString(R.string.str_home), R.string.str_home,
R.drawable.home_selector, R.id.tab_home));
mTabHost.addTab(newTab(getString(R.string.str_video),
R.string.str_video, R.drawable.video_icon_selector,
R.id.tab_video));
mTabHost.addTab(newTab(getString(R.string.str_audio),
R.string.str_audio, R.drawable.audio_icon_selector,
R.id.tab_audio));
mTabHost.addTab(newTab(getString(R.string.str_blog), R.string.str_blog,
R.drawable.blog_icon_selector, R.id.tab_blog));
mTabHost.addTab(newTab(getString(R.string.str_gal), R.string.str_gal,
R.drawable.gal_icon_selector, R.id.tab_gal));
mTabHost.addTab(newTab(getString(R.string.str_more), R.string.str_more,
R.drawable.more_icon_selector, R.id.tab_more));
mTabHost.setOnTabChangedListener(this);
}
private TabSpec newTab(String tag, int labelId, int tabImg, int tabContentId) {
View indicator = LayoutInflater.from(getActivity()).inflate(
R.layout.tab,
(ViewGroup) mRoot.findViewById(android.R.id.tabs), false);
TextView textView = ((TextView) indicator.findViewById(R.id.tab_text));
textView.setText(labelId);
textView.setTypeface(AppData.getTitleFont());
((ImageView) indicator.findViewById(R.id.tab_img))
.setImageResource(tabImg);
TabSpec tabSpec = mTabHost.newTabSpec(tag);
tabSpec.setIndicator(indicator);
tabSpec.setContent(tabContentId);
return tabSpec;
}
@Override
public void onTabChanged(String arg0) {
if (getString(R.string.str_home).equals(arg0)) {
updateTab(arg0, R.id.tab_home);
mCurrentTab = 0;
return;
} else if (getString(R.string.str_video).equals(arg0)) {
updateTab(arg0, R.id.tab_video);
mCurrentTab = 1;
return;
} else if (getString(R.string.str_audio).equals(arg0)) {
updateTab(arg0, R.id.tab_audio);
mCurrentTab = 2;
return;
} else if (getString(R.string.str_blog).equals(arg0)) {
updateTab(arg0, R.id.tab_blog);
mCurrentTab = 3;
return;
} else if (getString(R.string.str_gal).equals(arg0)) {
updateTab(arg0, R.id.tab_gal);
mCurrentTab = 4;
return;
} else if (getString(R.string.str_more).equals(arg0)) {
updateTab(arg0, R.id.tab_more);
mCurrentTab = mTabHost.getCurrentTab();
return;
}
}
private void updateTab(String tabId, int placeholder) {
FragmentManager fm = getFragmentManager();
mAudioFragment.stopPlay(tabId);
if (fm.findFragmentByTag(tabId) == null) {
if(AppData.isVideoPlaying && fm.findFragmentById(R.id.tab_video) != null){
fm.popBackStack();
}
switch (placeholder) {
case R.id.tab_home:
fm.beginTransaction()
.replace(placeholder, new HomeFragment(), tabId)
.commit();
break;
case R.id.tab_video:
fm.beginTransaction()
.replace(placeholder, new VideoFragment(), tabId)
.commit();
break;
case R.id.tab_audio:
fm.beginTransaction()
.replace(placeholder, mAudioFragment, tabId).commit();
break;
case R.id.tab_blog:
fm.beginTransaction()
.replace(placeholder, new BlogFragment(), tabId)
.commit();
break;
case R.id.tab_gal:
fm.beginTransaction()
.replace(placeholder, new GalleryFragment(), tabId)
.commit();
break;
case R.id.tab_more:
fm.beginTransaction()
.replace(placeholder, new MoreFragment(), tabId)
.commit();
break;
default:
fm.beginTransaction()
.replace(placeholder, new HomeFragment(), tabId)
.commit();
break;
}
} else if (fm.findFragmentByTag(tabId) != null) {
if (tabId.equalsIgnoreCase(getString(R.string.str_more))) {
fm.popBackStack();
}
if(AppData.isVideoPlaying && fm.findFragmentById(R.id.tab_video) != null){
fm.popBackStack();
}
}
}
public void OnAudioSelected(Audio audio) {
LiveStreamFragment audioDetailFragment = new LiveStreamFragment();
FragmentTransaction transaction = getActivity()
.getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.tab_audio, audioDetailFragment);
transaction.addToBackStack(null);
transaction.commit();
}
public void OnBlogSelected(Blog blog,String lang) {
BlogDetailFragment blogDetailFragment = new BlogDetailFragment();
Bundle bundle = new Bundle();
bundle.putParcelable("blog", blog);
bundle.putString("lang", lang);
blogDetailFragment.setArguments(bundle);
FragmentTransaction transaction = getActivity()
.getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.tab_blog, blogDetailFragment);
transaction.addToBackStack(null);
transaction.commit();
}
public void OnVideoSelected(Video video) {
FragmentTransaction transaction = getActivity()
.getSupportFragmentManager().beginTransaction();
if(video.getVideoType().equalsIgnoreCase("Youtube")){
Intent intent=new Intent(getActivity(),YoutubePlayActivity.class);
intent.putExtra("videoid", video.getVideoUrl());
intent.putExtra("title", video.getVideoTitle());
startActivity(intent);
}else{
LiveStreamFragment tubePlayFragment=new LiveStreamFragment();
Bundle bundle=new Bundle();
bundle.putString("live","VIDEO");
if(AppData.isAudioAvalableinSD(video.getVideoTitle().trim())){
try {
bundle.putString("url", AppData.getPath(video.getVideoTitle().trim()));
} catch (Exception e) {
bundle.putString("url", video.getVideoUrl());
}
}else{
bundle.putString("url", video.getVideoUrl());
}
tubePlayFragment.setArguments(bundle);
transaction.replace(R.id.tab_video, tubePlayFragment);
}
transaction.addToBackStack(null);
transaction.commit();
}
public void onMoreFragmentOptionSelected(final int option) {
switch (option) {
case 1:
AnnouncenentFragment fragment = new AnnouncenentFragment();
FragmentTransaction transaction = getActivity()
.getSupportFragmentManager().beginTransaction();
transaction.replace(R.id.tab_more, fragment);
transaction.addToBackStack(null);
transaction.commit();
break;
case 2:
MagzineFragment magzineFragment = new MagzineFragment();
transaction = getActivity().getSupportFragmentManager()
.beginTransaction();
transaction.replace(R.id.tab_more, magzineFragment);
transaction.addToBackStack(null);
transaction.commit();
break;
case 3:
CategoryFragment categoryFragment = new CategoryFragment();
transaction = getActivity().getSupportFragmentManager()
.beginTransaction();
transaction.replace(R.id.tab_more, categoryFragment);
transaction.addToBackStack(null);
transaction.commit();
break;
case 4:
LiveStreamFragment liveStreamFragment=new LiveStreamFragment();
transaction = getActivity().getSupportFragmentManager()
.beginTransaction();
Bundle bundle=new Bundle();
bundle.putString("live","LIVE STREAMING");
bundle.putString("url", appData.getLiveStreamVideo().getVideoUrl()); //345th Line
liveStreamFragment.setArguments(bundle);
transaction.replace(R.id.tab_more, liveStreamFragment);
transaction.addToBackStack(null);
transaction.commit();
break;
case 5:
PrayerRequestFragment prayerRequest = new PrayerRequestFragment();
transaction = getActivity().getSupportFragmentManager()
.beginTransaction();
transaction.replace(R.id.tab_more, prayerRequest);
transaction.addToBackStack(null);
transaction.commit();
break;
case 6:
SettingsFragment settingsFragment = new SettingsFragment();
transaction = getActivity().getSupportFragmentManager()
.beginTransaction();
transaction.replace(R.id.tab_more, settingsFragment);
transaction.addToBackStack(null);
transaction.commit();
break;
default:
break;
}
}
}
AppData.java:
package com.sit.gems.app;
public class AppData {
private static Context mContext;
private static Typeface typefaceTamil;
private static Typeface typefaceEnglish;
private static Typeface typefaceHindi;
private static Typeface typefaceTitle;
private List<Gallery> galleries;
private List<String> languages;
private String language;
private Map<String, List<Blog>> mapBlog;
private Map<String, List<Audio>> mapAudio;
private Map<String, List<Video>> mapVideo;
private List<Announcement> announcements;
private Map<String,List<Product>> products;
private List<Category> categories;
private boolean isPlaying;
private static int screenWidth;
public static boolean isVideoPlaying=false;
private int screenHeight;
private String magzfiles;
private List<Magzine> magzines;
private Video liveStreamVideo;
private String blogLang;
private String videoLang;
public AppData(Context context) {
mContext = context;
languages = new ArrayList<String>();
addLanguages();
WindowManager windowManager = (WindowManager) mContext
.getSystemService(Context.WINDOW_SERVICE);
Display display = windowManager.getDefaultDisplay();
screenWidth = display.getWidth();
screenHeight = display.getHeight();
mapAudio = new HashMap<String, List<Audio>>();
mapBlog = new HashMap<String, List<Blog>>();
mapVideo = new HashMap<String, List<Video>>();
this.products=new HashMap<String, List<Product>>();
}
private void addLanguages() {
languages.add("English");
languages.add("Tamil");
languages.add("Hindi");
}
private static void initFontStyles() {
typefaceTamil = Typeface.createFromAsset(mContext.getAssets(),
"fonts/tamil_nambi.ttf");
typefaceEnglish = Typeface.DEFAULT;
typefaceHindi = Typeface.createFromAsset(mContext.getAssets(),
"fonts/vigyapti.ttf");
typefaceTitle=Typeface.DEFAULT_BOLD;
}
public static Typeface getTamilFont() {
if (typefaceTamil == null) {
initFontStyles();
}
return typefaceTamil;
}
public static Typeface getTitleFont() {
if (typefaceTitle == null) {
initFontStyles();
}
return typefaceTitle;
}
public static Typeface getEnglishFont() {
if (typefaceEnglish == null) {
initFontStyles();
}
return typefaceEnglish;
}
public static Typeface getHindiFont() {
if (typefaceHindi == null) {
initFontStyles();
}
return typefaceHindi;
}
public List<String> getlanguages() {
return languages;
}
public void setBlogs(String lnag, List<Blog> blogs) {
if (mapBlog == null) {
mapBlog = new HashMap<String, List<Blog>>();
}
mapBlog.put(lnag, blogs);
}
public List<Gallery> getGalleries() {
return galleries;
}
public void setGalleries(List<Gallery> galleries) {
this.galleries = galleries;
}
public String getLanguage() {
return language;
}
public void setLanguage(String language) {
this.language = language;
}
public List<Blog> getBlogs(String lang) {
return mapBlog.get(lang);
}
public List<Audio> getAudios(String lang) {
return mapAudio.get(lang);
}
public void setAudios(String lang, List<Audio> audios) {
if (mapAudio == null) {
mapAudio = new HashMap<String, List<Audio>>();
}
mapAudio.put(lang, audios);
}
public void setVideos(String lang, List<Video> videos) {
if (mapVideo == null) {
mapVideo = new HashMap<String, List<Video>>();
}
mapVideo.put(lang, videos);
}
public List<Video> getVideos(String lang) {
return mapVideo.get(lang);
}
public static Typeface getTypeFace(String language) {
if (language.equalsIgnoreCase("English")) {
return getEnglishFont();
} else if (language.equalsIgnoreCase("Hindi")) {
return getHindiFont();
} else if (language.equalsIgnoreCase("Tamil")) {
return getTamilFont();
}
return getEnglishFont();
}
public void clearData() {
if (mapAudio != null)
mapAudio.clear();
if (mapBlog != null)
mapBlog.clear();
if (mapVideo != null)
mapVideo.clear();
if(galleries!=null)
galleries.clear();
if(announcements!=null)
announcements.clear();
if(products!=null)
products.clear();
if(magzines!=null)
magzines.clear();
setBlogLang(null);
setVideoLang(null);
}
public boolean isPlaying() {
return isPlaying;
}
public void setPlaying(boolean isPlaying) {
this.isPlaying = isPlaying;
}
public List<Announcement> getAnnouncements() {
return announcements;
}
public void setAnnouncements(List<Announcement> announcements) {
this.announcements = announcements;
}
public List<Product> getProducts(String cat) {
return products.get(cat);
}
public void setProducts(String cat,List<Product> products) {
if(this.products==null)
this.products=new HashMap<String, List<Product>>();
this.products.put(cat, products);
}
public List<Category> getCategories() {
return categories;
}
public void setCategories(List<Category> categories) {
this.categories = categories;
}
public static int getScreenWidth() {
return screenWidth;
}
public List<Magzine> getMagzines() {
return magzines;
}
public void setMagzines(List<Magzine> magzines) {
this.magzines = magzines;
}
public void setLiveStreamVideo(Video video) {
liveStreamVideo=video;
}
public Video getLiveStreamVideo() {
return liveStreamVideo;
}
public void setBlogLang(String lang) {
blogLang=lang;
}
public String getBlogLang() {
return blogLang;
}
public static boolean isAudioAvalableinSD(String title) {
String path ="";
try {
path = getPath(title);
if(path==null)
return false;
} catch (Exception e) {
return false;
}
try {
File f = new File(path);
if (!f.exists()) {
return false;
}
} catch (Exception e) {
return false;
}
return true;
}
public static String getPath(String title) throws Exception{
final String cachePath =
Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState()) ||
!isExternalStorageRemovable() ? getExternalCacheDir(mContext).getPath() :
mContext.getCacheDir().getPath();
return cachePath+ File.separator +title.trim() + ".mp3";
}
public static File getExternalCacheDir(Context context) {
if (Utils.hasFroyo()) {
return context.getExternalCacheDir();
}
final String cacheDir = "/Android/data/" + context.getPackageName() + "/cache/";
return new File(Environment.getExternalStorageDirectory().getPath() + cacheDir);
}
public static boolean isExternalStorageRemovable() {
if (Utils.hasGingerbread()) {
return Environment.isExternalStorageRemovable();
}
return true;
}
public String getVideoLang() {
return videoLang;
}
public void setVideoLang(String videoLang) {
this.videoLang = videoLang;
}
}
BaseFragment.java:
package com.sit.gems.app;
public class BaseFragment extends Fragment {
private Activity activity;
protected AppData appData;
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
this.activity = activity;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
appData = ((GemsApplication) activity.getApplication()).getAppData();
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return super.onCreateView(inflater, container, savedInstanceState);
}
}
HomeActivity.java:
package com.sit.gems.activity;
public class HomeActivity extends BaseActivity implements
VideoFragment.OnVideoSelectedListener,
AudioFragment.OnAudioSelectedListener,
BlogFragment.OnBlogSelectedListener,
MoreFragment.OnMoreFragmentOptionSelectedListener,
AnnouncenentFragment.OnAnnouncementSelectedListener,
ProductFragment.OnProductSelectedListener,
GalleryFragment.OnGalItemSelectedListener,
ProductDetailFragment.OnInquiryListener,
CategoryFragment.OnCategorySelectedListener,
MagzineFragment.OnMagzineSelectedListener{
private HomeBaseFragment fragment;
@Override
protected void onCreate(Bundle arg0) {
super.onCreate(arg0);
setContentView(R.layout.base_fragment);
AppPreferences.setAppPreferences(getApplicationContext());
getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
fragment = new HomeBaseFragment();
getSupportFragmentManager().beginTransaction()
.add(R.id.fragment_container, fragment).commit();
}
@Override
public void OnAudioSelected(Audio audio) {
fragment.OnAudioSelected(audio);
}
@Override
public void OnBlogSelected(Blog blog,String lang) {
fragment.OnBlogSelected(blog,lang);
}
@Override
protected void onDestroy() {
super.onDestroy();
appData.clearData();
}
@Override
public void OnVideoSelected(Video video) {
fragment.OnVideoSelected(video);
}
@Override
public void onMoreFragmentOptionSelected(int option) {
fragment.onMoreFragmentOptionSelected(option); //80th Line
}
@Override
public void OnAnnouncementSelected(Announcement announcement) {
fragment.onAnnouncementSelected(announcement);
}
@Override
public void OnProductSelected(Product product) {
fragment.onProductSelected(product);
}
@Override
public void OnGalItemSelected(String pos,String name) {
fragment.onGalItemSelected(pos,name);
}
@Override
public void OnInquirytSelected(Product product) {
fragment.onInquirytSelected(product);
}
@Override
public void OncategorySelected(String id,String name) {
fragment.oncategorySelected(id,name);
}
@Override
public void OnMagzineSelected(Magzine magzine) {
fragment.onMagzineSelected(magzine);
}
}
BaseActivity.java:
package com.sit.gems.app;
public class BaseActivity extends FragmentActivity {
protected AppData appData;
@Override
protected void onCreate(Bundle arg0) {
super.onCreate(arg0);
appData=((GemsApplication) getApplication()).getAppData();
}
public void onDestroyView() {
}
}
MoreFragment.java:
package com.sit.gems.frgment;
public class MoreFragment extends BaseFragment {
OnMoreFragmentOptionSelectedListener mCallBack;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.quickaction, null);
List<String> options=new ArrayList<String>();
options.add("Announcements");
options.add("Magazines");
options.add("Products");
options.add("Live Streaming");
options.add("Prayer Request");
options.add("Settings");
ListView listView =(ListView) view.findViewById(R.id.tracks);
listView.setAdapter(new MoreAdapter(getActivity(), 0, options));
listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
mCallBack.onMoreFragmentOptionSelected(arg2+1); //44th Line
}
});
return view;
}
@Override
public void onAttach(Activity activity) {
super.onAttach(activity);
try {
mCallBack = (OnMoreFragmentOptionSelectedListener) activity;
} catch (ClassCastException e) {
throw new ClassCastException(activity.toString()
+ " must implement OnHeadlineSelectedListener");
}
}
public interface OnMoreFragmentOptionSelectedListener{
public void onMoreFragmentOptionSelected(int option);
}
}
Output:
- If I click the Live Streaming Option,the Log Cat error will be occurred.
- If anybody know how to solve these type of errors.Your answer will be most welcome here.Thank You!
回答1:
Check your appData object and ensure it has been initialized. This looks like it is either null or is returning a null URL string.
回答2:
Looking at the line of code causing the problem, it doesn't look like you've initialized the appData instance anywhere, could this be why?
If this is not the problem, you could narrow the problem down or temporarily patch the problem by replacing this:
bundle.putString("url", appData.getLiveStreamVideo().getVideoUrl());
With this:
try {
Log.d("LiveStreamVideo", "Screen Width: " + appData.getScreenWidth());
Log.d("LiveStreamVideo", "Video URL: " + getLiveStreamVideo().getVideoUrl());
bundle.putString("url", appData.getLiveStreamVideo().getVideoUrl());
} catch (Exception e) {
e.printStackTrace();
}
If outputs the stack trace before you expect to see the first Log output, you know that appData is null. If it fails on the second log request, then getVideoUrl() is the problem.
It could be that getVideoUrl() is returning null as I can't see that it exists with any certainty. Maybe set a default value for this variable just to be sure:
private videoUrl = "";
来源：https://stackoverflow.com/questions/22039752/gems-app-live-stream-fragment