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android - 无法在恢复时启动 Activity ComponentInfo

转载 作者：行者123 更新时间：2023-11-30 04:12:56 29 4
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我的应用程序运行正常，但当应用程序进入后台时，它在应该恢复时崩溃了。正如您在源代码中看到的那样，我记录了 onStart、onStop 等事件。

在我的日志中，当我启动应用程序时，我可以看到 onStart、onResume。当我按下后退键时，我看到:onStop、STOP、onPause 和 onDestroy。

当我尝试重新启动应用程序时，它立即崩溃，除了“无法启动 Activity ComponentInfo java lang.NullPointerException”之外，日志中没有其他消息。

我怎样才能避免这种情况？

public class Start extends Activity {

private Handler handler = new Handler();
private ArrayList<String> discussionThread;
private EditText textMessage;

private ListView listview;

private ConnectionConfiguration config;
private Presence presence;
private MultiUserChat muc;
private DiscussionHistory history;
private PacketFilter filter;
private MyCustomAdapter discussionThreadAdapter;
private XMPPConnection connection;


/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    try {
        initConnection();
    } catch (XMPPException e) {
        e.printStackTrace();
    }

    final EditText textMessage = (EditText) this.findViewById(R.id.message);        
    listview = (ListView) this.findViewById(R.id.list);

    discussionThread = new ArrayList<String>();
    discussionThreadAdapter = new MyCustomAdapter();
    listview.setAdapter(discussionThreadAdapter);

    Button send = (Button) this.findViewById(R.id.send);
    send.setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {
            String text = textMessage.getText().toString();

            Message msg = new Message(ROOM, Message.Type.groupchat);
            msg.setBody(text);
            connection.sendPacket(msg);
            discussionThreadAdapter.notifyDataSetChanged();
            textMessage.setText("");
        }
    });


    textMessage.setOnKeyListener(new OnKeyListener()
    {
        public boolean onKey(View v, int keyCode, KeyEvent event)
        {
            if (event.getAction() == KeyEvent.ACTION_DOWN)
            {
                switch (keyCode)
                {
                    case KeyEvent.KEYCODE_DPAD_CENTER:
                    case KeyEvent.KEYCODE_ENTER:
                        SendText();
                        return true;
                    default:
                        break;
                }
            }
            return false;
        }
    });
}


private void initConnection() throws XMPPException {
    config = new ConnectionConfiguration(SERVER_HOST, SERVER_PORT, SERVICE_NAME);
    connection = new XMPPConnection(config);
    connection.connect();
    connection.login(LOGIN, PASSWORD);
    presence = new Presence(Presence.Type.available);

    connection.sendPacket(presence);

    muc = new MultiUserChat(connection, ROOM);
    history = new DiscussionHistory();

    history.setMaxStanzas(25);

    muc.join(LOGIN, PASSWORD, history, SmackConfiguration.getPacketReplyTimeout());

    filter = new MessageTypeFilter(Message.Type.groupchat);

    connection.addPacketListener(new PacketListener() {

        public void processPacket(Packet packet) {
            Message message = (Message) packet;
            if (message.getBody() != null) {
                String fromName = message.getFrom().substring(48);
                String nieuweRegel = fromName + ": " + message.getBody();

                fromName = fromName.toUpperCase();

                if (fromName.equals(LOGIN.toUpperCase())) {
                    discussionThreadAdapter.addVanMijItem(nieuweRegel);
                } else {
                    discussionThreadAdapter.addVanAnderItem(nieuweRegel);
                }

            }
        }
    }, filter);

}

private void Notify() {
    discussionThreadAdapter.notifyDataSetChanged();
    listview.setSelection(discussionThreadAdapter.getCount());
}

private class MyCustomAdapter extends BaseAdapter {

    private static final int BERICHT_VAN_ANDER = 0;
    private static final int BERICHT_VAN_MIJ = 1;
    private static final int TYPE_MAX_COUNT = BERICHT_VAN_MIJ + 1;

    private LayoutInflater mInflater;

    private TreeSet<Integer> mySet = new TreeSet<Integer>();

    public MyCustomAdapter() {
        mInflater = (LayoutInflater)getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public void addVanAnderItem(final String item) {
        discussionThread.add(item);
        handler.post(new Runnable() {
            public void run() {
                Notify();
            }
        });

    }

    public void addVanMijItem(final String item) {
        discussionThread.add(item);
        mySet.add(discussionThread.size() - 1);
        handler.post(new Runnable() {
            public void run() {
                Notify();
            }
        });
    }

    @Override
    public int getItemViewType(int position) {
        return mySet.contains(position) ? BERICHT_VAN_MIJ : BERICHT_VAN_ANDER;
    }

    @Override
    public int getViewTypeCount() {
        return TYPE_MAX_COUNT;
    }

    @Override
    public int getCount() {
        return discussionThread.size();
    }

    @Override
    public String getItem(int position) {
        return discussionThread.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder holder = null;
        int type = getItemViewType(position);
        if (convertView == null) {
            holder = new ViewHolder();
            switch (type) {
                case BERICHT_VAN_ANDER:
                    convertView = mInflater.inflate(R.layout.bericht_van_ander_item, null);
                    holder.textView = (TextView)convertView.findViewById(R.id.textline);
                    break;
                case BERICHT_VAN_MIJ:
                    convertView = mInflater.inflate(R.layout.bericht_van_mij_item, null);
                    holder.textView = (TextView)convertView.findViewById(R.id.textline);
                    break;
            }
            convertView.setTag(holder);
        } else {
            holder = (ViewHolder)convertView.getTag();
        }
        holder.textView.setText(discussionThread.get(position));
        return convertView;
    }

}

public static class ViewHolder {
    public TextView textView;
}

private void SendText() {

    InputMethodManager imm = (InputMethodManager)getSystemService(Context.INPUT_METHOD_SERVICE);
    imm.hideSoftInputFromWindow(textMessage.getWindowToken(), 0);

    String text = textMessage.getText().toString();

    Message msg = new Message(ROOM, Message.Type.groupchat);
    msg.setBody(text);
    connection.sendPacket(msg);
    textMessage.setText("");
}

public void onStart() {
    super.onStart();
    Log.i("CONN", "onStart");
    startConnection();
}

public void onRestart() {
    super.onRestart();
    Log.i("CONN", "onReStart");
    startConnection();
}

public void onResume() {
    super.onResume();
    Log.i("CONN", "onResume");
    startConnection();
}

public void onPause() {
    super.onPause();
    Log.i("CONN", "onPause");
    stopConnection();

}

public void onStop() {
    super.onStop();
    Log.i("CONN", "onStop");
    stopConnection();
}

public void onDestroy() {
    super.onDestroy();
    Log.i("CONN", "onDestroy");
    stopConnection();
}

private void stopConnection() {

    if (connection != null) {

        Log.i("CONN", "STOP");

        connection.disconnect(presence);

        connection = null;
        filter = null;
        history = null;
        muc = null;
        presence = null;
        config = null;
        discussionThreadAdapter = null;


    }

}

private void startConnection() {

    if (connection.isConnected() ) {

    } else {

        Log.i("CONN", "START");

        try {
            initConnection();
        } catch (XMPPException e) {
            e.printStackTrace();
        }
    }
}

好的，我更改了以下内容:

   private void startConnection() {

    if (connection != null ) {

        Log.i("CONN", "RUNNING");

    } else {

        Log.i("CONN", "START");

        try {
            initConnection();
        } catch (XMPPException e) {
            e.printStackTrace();
        }
    }
}

我启动应用程序，一切正常。日志:

05-12 08:40:21.743: D/AndroidRuntime(491): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<< 05-12 08:40:21.743: D/AndroidRuntime(491): CheckJNI is ON

05-12 08:40:22.065: D/AndroidRuntime(491): --- registering native functions ---

05-12 08:40:23.353: D/AndroidRuntime(491): Shutting down VM

05-12 08:40:23.363: D/dalvikvm(491): Debugger has detached; object registry had 1 entries

05-12 08:40:23.393: I/AndroidRuntime(491): NOTE: attach of thread 'Binder Thread #3' failed

05-12 08:40:24.184: D/AndroidRuntime(499): >>>>>>>>>>>>>> AndroidRuntime START <<<<<<<<<<<<<<

05-12 08:40:24.184: D/AndroidRuntime(499): CheckJNI is ON

05-12 08:40:24.523: D/AndroidRuntime(499): --- registering native functions ---

05-12 08:40:25.873: I/ActivityManager(70): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=nl.yeswecanclinics.chat/.Start }

05-12 08:40:25.965: D/AndroidRuntime(499): Shutting down VM

05-12 08:40:25.973: D/dalvikvm(499): Debugger has detached; object registry had 1 entries

05-12 08:40:26.034: I/AndroidRuntime(499): NOTE: attach of thread 'Binder Thread #3' failed

05-12 08:40:26.105: I/ActivityManager(70): Start proc nl.yeswecanclinics.chat for activity nl.yeswecanclinics.chat/.Start: pid=506 uid=10032 gids={3003, 1015}

05-12 08:40:27.843: I/global(506): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:40:27.843: I/global(506): Default buffer size used in BufferedWriter constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:40:28.294: W/System.err(506): java.security.KeyStoreException: KeyStore jks implementation not found

05-12 08:40:28.294: W/System.err(506): at java.security.KeyStore.getInstance(KeyStore.java:134)

05-12 08:40:28.294: W/System.err(506): at org.jivesoftware.smack.ServerTrustManager.(ServerTrustManager.java:61)

05-12 08:40:28.294: W/System.err(506): at org.jivesoftware.smack.XMPPConnection.proceedTLSReceived(XMPPConnection.java:832)

05-12 08:40:28.304: W/System.err(506): at org.jivesoftware.smack.PacketReader.parsePackets(PacketReader.java:268)

05-12 08:40:28.304: W/System.err(506): at org.jivesoftware.smack.PacketReader.access$000(PacketReader.java:44)

05-12 08:40:28.313: W/System.err(506): at org.jivesoftware.smack.PacketReader$1.run(PacketReader.java:71)

05-12 08:40:29.004: I/global(506): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:40:29.014: I/global(506): Default buffer size used in BufferedWriter constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:40:29.483: D/dalvikvm(506): GC_FOR_MALLOC freed 3668 objects / 280752 bytes in 153ms

05-12 08:40:29.663: I/CONN(506): onStart

05-12 08:40:29.685: I/CONN(506): RUNNING

05-12 08:40:29.685: I/CONN(506): onResume

05-12 08:40:29.693: I/CONN(506): RUNNING

05-12 08:40:30.633: I/ActivityManager(70): Displayed activity nl.yeswecanclinics.chat/.Start: 4712 ms (total 384269 ms)

05-12 08:40:37.114: D/dalvikvm(175): GC_EXPLICIT freed 444 objects / 22064 bytes in 122ms

I PRESS THE BACK BUTTON

05-12 08:41:07.253: W/KeyCharacterMap(506): No keyboard for id 0

05-12 08:41:07.253: W/KeyCharacterMap(506): Using default keymap: /system/usr/keychars/qwerty.kcm.bin

05-12 08:41:07.403: I/CONN(506): onPause

05-12 08:41:07.403: I/CONN(506): STOP

05-12 08:41:07.784: W/InputManagerService(70): Starting input on non-focused client com.android.internal.view.IInputMethodClient$Stub$Proxy@45066cf8 (uid=10032 pid=506)

05-12 08:41:07.804: W/IInputConnectionWrapper(506): showStatusIcon on inactive InputConnection

05-12 08:41:08.173: I/CONN(506): onStop

05-12 08:41:08.173: I/CONN(506): onDestroy

I RESTART THE APP BY CLICKING THE ICON

05-12 08:41:30.583: I/global(506): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:41:30.623: I/global(506): Default buffer size used in BufferedWriter constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:41:31.663: W/System.err(506): java.security.KeyStoreException: KeyStore jks implementation not found

05-12 08:41:31.663: W/System.err(506): at java.security.KeyStore.getInstance(KeyStore.java:134)

05-12 08:41:31.663: W/System.err(506): at org.jivesoftware.smack.ServerTrustManager.(ServerTrustManager.java:61)

05-12 08:41:31.674: W/System.err(506): at org.jivesoftware.smack.XMPPConnection.proceedTLSReceived(XMPPConnection.java:832)

05-12 08:41:31.674: W/System.err(506): at org.jivesoftware.smack.PacketReader.parsePackets(PacketReader.java:268)

05-12 08:41:31.683: W/System.err(506): at org.jivesoftware.smack.PacketReader.access$000(PacketReader.java:44)

05-12 08:41:31.683: W/System.err(506): at org.jivesoftware.smack.PacketReader$1.run(PacketReader.java:71)

05-12 08:41:31.984: I/global(506): Default buffer size used in BufferedReader constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:41:31.994: I/global(506): Default buffer size used in BufferedWriter constructor. It would be better to be explicit if an 8k-char buffer is required.

05-12 08:41:32.043: D/AndroidRuntime(506): Shutting down VM

05-12 08:41:32.043: W/dalvikvm(506): threadid=1: thread exiting with uncaught exception (group=0x4001d800)

05-12 08:41:32.214: D/dalvikvm(506): GC_FOR_MALLOC freed 5507 objects / 388504 bytes in 147ms

05-12 08:41:32.226: D/NativeCrypto(506): Freeing OpenSSL session

05-12 08:41:32.234: E/AndroidRuntime(506): FATAL EXCEPTION: main

05-12 08:41:32.234: E/AndroidRuntime(506): java.lang.RuntimeException: Unable to start activity ComponentInfo{nl.yeswecanclinics.chat/nl.yeswecanclinics.chat.Start}: java.lang.NullPointerException

05-12 08:41:32.234: E/AndroidRuntime(506): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.app.ActivityThread.access$2300(ActivityThread.java:125)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.os.Handler.dispatchMessage(Handler.java:99)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.os.Looper.loop(Looper.java:123)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.app.ActivityThread.main(ActivityThread.java:4627)

05-12 08:41:32.234: E/AndroidRuntime(506): at java.lang.reflect.Method.invokeNative(Native Method)

05-12 08:41:32.234: E/AndroidRuntime(506): at java.lang.reflect.Method.invoke(Method.java:521)

05-12 08:41:32.234: E/AndroidRuntime(506): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868) 05-12 08:41:32.234: E/AndroidRuntime(506): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)

05-12 08:41:32.234: E/AndroidRuntime(506): at dalvik.system.NativeStart.main(Native Method)

05-12 08:41:32.234: E/AndroidRuntime(506): Caused by: java.lang.NullPointerException

05-12 08:41:32.234: E/AndroidRuntime(506): at org.jivesoftware.smackx.muc.MultiUserChat$1.connectionCreated(MultiUserChat.java:114)

05-12 08:41:32.234: E/AndroidRuntime(506): at org.jivesoftware.smack.XMPPConnection.initConnection(XMPPConnection.java:618)

05-12 08:41:32.234: E/AndroidRuntime(506): at org.jivesoftware.smack.XMPPConnection.connectUsingConfiguration(XMPPConnection.java:565)

05-12 08:41:32.234: E/AndroidRuntime(506): at org.jivesoftware.smack.XMPPConnection.connect(XMPPConnection.java:991)

05-12 08:41:32.234: E/AndroidRuntime(506): at nl.yeswecanclinics.chat.Start.initConnection(Start.java:131)

05-12 08:41:32.234: E/AndroidRuntime(506): at nl.yeswecanclinics.chat.Start.onCreate(Start.java:71)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)

05-12 08:41:32.234: E/AndroidRuntime(506): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)

05-12 08:41:32.234: E/AndroidRuntime(506): ... 11 more

最佳答案

虽然 Marek 的回答肯定没有错(这实际上可能是您得到 NullPointerException 的原因)，但我知道的一件事是您不应该尝试在 UI 线程上建立连接.如果建立连接需要超过几秒钟的时间，这将不可避免地导致您的应用程序崩溃。您应该创建一个 AsnycTask 并在那里更改您的连接和状态。

关于android - 无法在恢复时启动 Activity ComponentInfo，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10529769/

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