android - 奇怪的“无法发送事件”和“没有订阅者注册事件”问题

Question

我已经尝试调试这个东西几个小时了，我真的看不到这里的问题。

这是我的主要活动。这里要查找的主要内容是ArrayList<Servico>, 作为Servico自定义对象。我创建了一个简单的“事件”类——ServicoActual它只有一个Servico对象引用（和一个构造函数/getter）：

import android.app.Activity;
import android.app.Fragment;
import android.app.FragmentManager;
import android.app.SearchManager;
import android.content.Intent;
import android.content.res.Configuration;
import android.os.Bundle;
import android.support.v4.app.ActionBarDrawerToggle;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import net.pedromoreira.billper.events.ServicoActual;

import java.util.ArrayList;
import java.util.Locale;

import de.greenrobot.event.EventBus;


public class MainActivity extends Activity {
    private DrawerLayout mDrawerLayout;
    private ListView mDrawerList;
    private ActionBarDrawerToggle mDrawerToggle;

    private CharSequence mDrawerTitle;
    private CharSequence mTitle;
    private ArrayList<Servico> servicos;
    //private String[] mPlanetTitles;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        servicos = new ArrayList<Servico>();
        servicos.add(new Servico("Luz"));
        servicos.add(new Servico("Água"));
        servicos.add(new Servico("Gás"));

        //Log.i("onCreate", "Servicos: " + servicos.size());

        setContentView(R.layout.activity_main);

        mTitle = mDrawerTitle = getTitle();
        //mPlanetTitles = getResources().getStringArray(R.array.planets_array);

        mDrawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
        mDrawerList = (ListView) findViewById(R.id.left_drawer);

        // set a custom shadow that overlays the main content when the drawer opens
        mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.START);
        // set up the drawer's list view with items and click listener
        mDrawerList.setAdapter(new ArrayAdapter<Servico>(this,
                R.layout.drawer_list_item, servicos));
        mDrawerList.setOnItemClickListener(new DrawerItemClickListener());

        // enable ActionBar app icon to behave as action to toggle nav drawer
        getActionBar().setDisplayHomeAsUpEnabled(true);
        getActionBar().setHomeButtonEnabled(true);

        // ActionBarDrawerToggle ties together the the proper interactions
        // between the sliding drawer and the action bar app icon
        mDrawerToggle = new ActionBarDrawerToggle(
                this,                  /* host Activity */
                mDrawerLayout,         /* DrawerLayout object */
                R.drawable.ic_drawer,  /* nav drawer image to replace 'Up' caret */
                R.string.drawer_open,  /* "open drawer" description for accessibility */
                R.string.drawer_close  /* "close drawer" description for accessibility */
        ) {
            public void onDrawerClosed(View view) {
                getActionBar().setTitle(mTitle);
                invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }

            public void onDrawerOpened(View drawerView) {
                getActionBar().setTitle(mDrawerTitle);
                invalidateOptionsMenu(); // creates call to onPrepareOptionsMenu()
            }
        };
        mDrawerLayout.setDrawerListener(mDrawerToggle);

        if (savedInstanceState == null) {
            selectItem(0);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.main, menu);
        return super.onCreateOptionsMenu(menu);
    }

    /* Called whenever we call invalidateOptionsMenu() */
    @Override
    public boolean onPrepareOptionsMenu(Menu menu) {
        // If the nav drawer is open, hide action items related to the content view
        boolean drawerOpen = mDrawerLayout.isDrawerOpen(mDrawerList);
        menu.findItem(R.id.action_websearch).setVisible(!drawerOpen);
        return super.onPrepareOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // The action bar home/up action should open or close the drawer.
        // ActionBarDrawerToggle will take care of this.
        if (mDrawerToggle.onOptionsItemSelected(item)) {
            return true;
        }
        // Handle action buttons
        switch(item.getItemId()) {
            case R.id.action_websearch:
                // create intent to perform web search for this planet
                Intent intent = new Intent(Intent.ACTION_WEB_SEARCH);
                intent.putExtra(SearchManager.QUERY, getActionBar().getTitle());
                // catch event that there's no activity to handle intent
                if (intent.resolveActivity(getPackageManager()) != null) {
                    startActivity(intent);
                } else {
                    Toast.makeText(this, R.string.app_not_available, Toast.LENGTH_LONG).show();
                }
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

    /* The click listener for ListView in the navigation drawer */
    private class DrawerItemClickListener implements ListView.OnItemClickListener {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            selectItem(position);
            Log.i("DrawerItemClickListener", "Position: " + position);
        }
    }

    private void selectItem(int position) {
        // update the main content by replacing fragments
        Fragment fragment = new ServicoFragment();
        //Bundle args = new Bundle();
        //args.putInt(ServicoFragment.ARG_PLANET_NUMBER, position);
        //fragment.setArguments(args);

        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction().replace(R.id.content_frame, fragment).commit();
        Log.i("selectItem", "Servico: " + servicos.get(position).getNome());
        EventBus.getDefault().postSticky(new ServicoActual(servicos.get(position)));

        // update selected item and title, then close the drawer
        mDrawerList.setItemChecked(position, true);
        setTitle(servicos.get(position).getNome());
        mDrawerLayout.closeDrawer(mDrawerList);
    }

    @Override
    public void setTitle(CharSequence title) {
        mTitle = title;
        getActionBar().setTitle(mTitle);
    }

    /**
     * When using the ActionBarDrawerToggle, you must call it during
     * onPostCreate() and onConfigurationChanged()...
     */

    @Override
    protected void onPostCreate(Bundle savedInstanceState) {
        super.onPostCreate(savedInstanceState);
        // Sync the toggle state after onRestoreInstanceState has occurred.
        mDrawerToggle.syncState();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        // Pass any configuration change to the drawer toggls
        mDrawerToggle.onConfigurationChanged(newConfig);
    }

    /**
     * Fragment that appears in the "content_frame"
     */
    public static class ServicoFragment extends Fragment {
        //public static final String ARG_PLANET_NUMBER = "planet_number";

        private TextView mTestText;

        public ServicoFragment() {
            // Empty constructor required for fragment subclasses
        }

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            EventBus.getDefault().registerSticky(this);
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_servico, container, false);
            //int i = getArguments().getInt(ARG_PLANET_NUMBER);
            //String planet = getResources().getStringArray(R.array.planets_array)[i];

            //int imageId = getResources().getIdentifier(planet.toLowerCase(Locale.getDefault()),
            //        "drawable", getActivity().getPackageName());
            //((ImageView) rootView.findViewById(R.id.image)).setImageResource(imageId);

            //getActivity().setTitle(planet);

            mTestText = ((TextView) rootView.findViewById(R.id.test_text));
            Log.i("onCreateView", "mTestText: " + mTestText.toString());
            mTestText.setText("xpto");

            return rootView;
        }

        public void onEvent(ServicoActual e){
            Servico servico = e.getServico();
            Log.i("onEvent", "Servico: " + servico.getNome());
            getActivity().setTitle(servico.getNome());
            mTestText.setText(servico.getNome());
        }
    }
}

因此，当单击抽屉列表项时，我试图将相应的Servico（在ServicoActual“事件”内）传递给ServicoFragment，它应该将Servico' 的名称写入其TextView.

这是单击第一项 (0) 时发生的情况：

07-13 00:50:35.388  26244-26244/net.pedromoreira.billper I/ViewRootImpl﹕ ViewRoot's Touch Event : Touch Down
07-13 00:50:35.628  26244-26244/net.pedromoreira.billper I/ViewRootImpl﹕ ViewRoot's Touch Event : Touch UP
07-13 00:50:36.308  26244-26244/net.pedromoreira.billper I/ViewRootImpl﹕ ViewRoot's Touch Event : Touch Down
07-13 00:50:36.358  26244-26244/net.pedromoreira.billper I/ViewRootImpl﹕ ViewRoot's Touch Event : Touch UP
07-13 00:50:36.428  26244-26244/net.pedromoreira.billper I/selectItem﹕ Servico: Luz
07-13 00:50:36.428  26244-26244/net.pedromoreira.billper I/onEvent﹕ Servico: Luz
07-13 00:50:36.458  26244-26244/net.pedromoreira.billper E/Event﹕ Could not dispatch event: class net.pedromoreira.billper.events.ServicoActual to subscribing class class net.pedromoreira.billper.MainActivity$ServicoFragment
    java.lang.NullPointerException
            at net.pedromoreira.billper.MainActivity$ServicoFragment.onEvent(MainActivity.java:235)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at de.greenrobot.event.EventBus.invokeSubscriber(EventBus.java:569)
            at de.greenrobot.event.EventBus.postToSubscription(EventBus.java:500)
            at de.greenrobot.event.EventBus.postSingleEvent(EventBus.java:475)
            at de.greenrobot.event.EventBus.post(EventBus.java:365)
            at de.greenrobot.event.EventBus.postSticky(EventBus.java:406)
            at net.pedromoreira.billper.MainActivity.selectItem(MainActivity.java:161)
            at net.pedromoreira.billper.MainActivity.access$300(MainActivity.java:35)
            at net.pedromoreira.billper.MainActivity$DrawerItemClickListener.onItemClick(MainActivity.java:146)
            at android.widget.AdapterView.performItemClick(AdapterView.java:299)
            at android.widget.AbsListView.performItemClick(AbsListView.java:1158)
            at android.widget.AbsListView$PerformClick.run(AbsListView.java:2957)
            at android.widget.AbsListView$3.run(AbsListView.java:3849)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5105)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
            at dalvik.system.NativeStart.main(Native Method)
07-13 00:50:36.458  26244-26244/net.pedromoreira.billper I/onEvent﹕ Servico: Luz
07-13 00:50:36.468  26244-26244/net.pedromoreira.billper D/Event﹕ No subscribers registered for event class de.greenrobot.event.SubscriberExceptionEvent
07-13 00:50:36.468  26244-26244/net.pedromoreira.billper I/DrawerItemClickListener﹕ Position: 0
07-13 00:50:36.498  26244-26244/net.pedromoreira.billper I/onEvent﹕ Servico: Luz
07-13 00:50:36.508  26244-26244/net.pedromoreira.billper E/Event﹕ Could not dispatch event: class net.pedromoreira.billper.events.ServicoActual to subscribing class class net.pedromoreira.billper.MainActivity$ServicoFragment
    java.lang.NullPointerException
            at net.pedromoreira.billper.MainActivity$ServicoFragment.onEvent(MainActivity.java:236)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at de.greenrobot.event.EventBus.invokeSubscriber(EventBus.java:569)
            at de.greenrobot.event.EventBus.postToSubscription(EventBus.java:500)
            at de.greenrobot.event.EventBus.subscribe(EventBus.java:288)
            at de.greenrobot.event.EventBus.register(EventBus.java:189)
            at de.greenrobot.event.EventBus.registerSticky(EventBus.java:166)
            at net.pedromoreira.billper.MainActivity$ServicoFragment.onCreate(MainActivity.java:209)
            at android.app.Fragment.performCreate(Fragment.java:1688)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:860)
            at android.app.FragmentManagerImpl.moveToState(FragmentManager.java:1063)
            at android.app.BackStackRecord.run(BackStackRecord.java:684)
            at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1450)
            at android.app.FragmentManagerImpl$1.run(FragmentManager.java:444)
            at android.os.Handler.handleCallback(Handler.java:733)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5105)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:792)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:608)
            at dalvik.system.NativeStart.main(Native Method)
07-13 00:50:36.508  26244-26244/net.pedromoreira.billper D/Event﹕ No subscribers registered for event class de.greenrobot.event.SubscriberExceptionEvent
07-13 00:50:36.508  26244-26244/net.pedromoreira.billper I/onCreateView﹕ mTestText: android.widget.TextView{429216d0 V.ED.... ......ID 0,0-0,0 #7f090003 app:id/test_text}

我做错了什么？

score 7 · Accepted Answer

我错了。警告是关于在发布时没有人注册的。实际的异常可能与事件运行时未附加活动有关。你可能想要onAttach().

http://developer.android.com/reference/android/app/Fragment.html#onAttach(android.app.Activity)

仍然感觉像是一种奇怪的架构，但说我的应用程序都没有奇怪的架构是错误的。

更新：

让我重新开始。我最初的回答说EventBus崩溃了，因为没有人为您的活动注册。但是，该日志语句不是崩溃。这只是一个调试。我发现EventBus在这种事情上有点激进，但总的来说它可能会有所帮助。

NullPointerException 是不同的。当onCreate()在您的片段上调用时，它会注册到您的粘性事件。这立即调用您的事件。它就在堆栈中。此时，您的片段可能onCreateView()已附加到您的活动，但（可能）没有被调用，因此您的 TextView 不存在。我看不到哪一行确切地抛出了异常。查看生命周期：

如果要使用粘性事件，则需要在 Fragment 生命周期的后期进行注册。我猜你想要onCreateView()/ onDestroyView()。我从未见过这种注册/注销配对，但它应该可以工作。

一般来说，我认为我们会使用片段的参数来执行此操作，或者可能直接从活动中获取数据，但是所有方法都相当笨拙和/或冗长，这就是为什么我仍然是“仅在需要时”的那种碎片的人。

另一种方法是在 UI 线程中创建一个处理程序并发布一个执行注册的 Runnable，它应该在挂起的生命周期事件之后安排它，但如果您不需要，请不要这样做。

此外，您可能只发布/注册 theServico而不是ServicoActual，但这对您的问题没有任何影响。

android - 奇怪的“无法发送事件”和“没有订阅者注册事件”问题

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