Question

我有ViewPager和带片段的适配器。

它工作得非常好，但是当我点击“主页按钮”并且20分钟后回到我的应用程序时，应用程序崩溃了“nullpointexception”。

这是我的代码：

主：

pager = (ViewPager)findViewById(R.id.pager);
pager.setOffscreenPageLimit(1); getFragments();
pageAdapter = new AdapterArticles(getSupportFragmentManager(), fragments);
pager.setAdapter(pageAdapter);
pager.setCurrentItem(extras.getInt("position"); 
pager.setOnPageChangeListener(this);

片段：

public static final FragmentArticle newInstance(RssItem item){

    FragmentArticle f = new FragmentArticle();
       Bundle bdl = new Bundle(1);
       bdl.putParcelable("item", item);
       f.setArguments(bdl);

       return f;
     }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
       Bundle savedInstanceState){
       View convert = inflater.inflate(R.layout.view_event, container, false);

       TextView title = (TextView)convert.findViewById(R.id.title);
       TextView info = (TextView)convert.findViewById(R.id.info);


       Item item = getArguments().getParcelable("item");

       info.setText(item.getItemDate());
       title.setText(item.getTitle());


       return convert;
     }

堆栈：

02-04 10:05:53.545: E/AndroidRuntime(19517): FATAL EXCEPTION: main
02-04 10:05:53.545: E/AndroidRuntime(19517): java.lang.RuntimeException: Unable to start activity ComponentInfo{pl.wm.ga/pl.wm.scroll.ActivityArticlesScroll}: java.lang.NullPointerException
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2194)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2229)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.ActivityThread.access$600(ActivityThread.java:139)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1261)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.os.Handler.dispatchMessage(Handler.java:99)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.os.Looper.loop(Looper.java:154)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.ActivityThread.main(ActivityThread.java:4945)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at java.lang.reflect.Method.invokeNative(Native Method)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at java.lang.reflect.Method.invoke(Method.java:511)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at dalvik.system.NativeStart.main(Native Method)
02-04 10:05:53.545: E/AndroidRuntime(19517): Caused by: java.lang.NullPointerException
02-04 10:05:53.545: E/AndroidRuntime(19517):    at pl.wm.scroll.ActivityArticlesScroll.getFragments(ActivityArticlesScroll.java:132)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at pl.wm.scroll.ActivityArticlesScroll.onCreate(ActivityArticlesScroll.java:69)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.Activity.performCreate(Activity.java:4531)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1071)
02-04 10:05:53.545: E/AndroidRuntime(19517):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2150)
02-04 10:05:53.545: E/AndroidRuntime(19517):    ... 11 more

我在这段代码中检查是否有问题：我有数据的类，但是当活动恢复并且我使用getFeed时，它是null。

public class ArticlesManager {

     private static ArticlesManager instance = null;
     private HashMap<String, RssFeed> feedMap = new HashMap<String, RssFeed>(); 

        private ArticlesManager() {

        }

        public static ArticlesManager getInstance() {
            if(instance == null) {
                instance = new ArticlesManager();
             }
             return instance;
        }

        public RssFeed getFeed(String name) {
            RssFeed rssFeed = feedMap.get(name);
            return rssFeed;
        }

        public void addFeed(String name, RssFeed rssFeed){
            feedMap.put(name, rssFeed);
        }

        public void clear(){
            feedMap.clear();
        }

        public void clearArticle(String name){
            feedMap.remove(name);
        }
}

Answer 1

我认为您的额外内容可能为null或者getInt（“position”）可能为null。发布完整的堆栈跟踪，以便我们了解正在发生的事情。此外，您应该提供您的活动或片段的完整代码，您将获得这些额外内容。

恢复时的ViewPager异常

1 个答案: