Android 系统服务错误，在 onCreate() 之前服务不可用

Question

我正在尝试在 android(目标 4.3)中使用带有操作栏的 fragment 概念。为此，我使用了有效的导航应用程序(作为我的基础和构建)。我喜欢滑动 View 的想法，并希望保留此功能。

Link to swipe view android page

我在实现应用程序和使用 fragment 的基本功能方面没有遇到任何问题，但事情变得棘手了。我之前开发了一个可以工作的蓝牙应用程序(它本身可以工作)，现在我正试图将它作为我的新应用程序中的一个 fragment 来实现。目前，我的应用程序中的操作栏具有三个选项卡:欢迎页面、传感器和 GPS。对于这个问题，我只关心传感器选项卡。

安卓代码

我的代码超过 700 行，所以我只会在这里发布相关的 spinets。如果您需要其他任何东西，请发表评论，我会提供。

    /* Relevant imports here 
    *  including: android.support.v7.app.ActionBar;
    *  android.support.v7.app.ActionBarActivity;
    *  android.support.v4.app.FragmentTransaction;
    */ 

主 Activity 类

 AppSectionsPagerAdapter mAppSectionsPagerAdapter;

    /**
     * The {@link ViewPager} that will display the three primary sections of the app, one at a
     * time.
     */
    ViewPager mViewPager;

    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        // Create the adapter that will return a fragment for each of the three primary sections
        // of the app.
        mAppSectionsPagerAdapter = new AppSectionsPagerAdapter(getSupportFragmentManager());

        // Set up the action bar.
        final ActionBar actionBar = getSupportActionBar();

        // Specify that the Home/Up button should not be enabled, since there is no hierarchical
        // parent.
        actionBar.setHomeButtonEnabled(false);

        // Specify that we will be displaying tabs in the action bar.
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        // Set up the ViewPager, attaching the adapter and setting up a listener for when the
        // user swipes between sections.
        mViewPager = (ViewPager) findViewById(R.id.pager);
        mViewPager.setAdapter(mAppSectionsPagerAdapter);
        mViewPager.setOnPageChangeListener(new ViewPager.SimpleOnPageChangeListener() {
            @Override
            public void onPageSelected(int position) {
                // When swiping between different app sections, select the corresponding tab.
                // We can also use ActionBar.Tab#select() to do this if we have a reference to the
                // Tab.
                actionBar.setSelectedNavigationItem(position);
            }
        });


        // For each of the sections in the app, add a tab to the action bar.
        for (int i = 0; i < mAppSectionsPagerAdapter.getCount(); i++) {
            // Create a tab with text corresponding to the page title defined by the adapter.
            // Also specify this Activity object, which implements the TabListener interface, as the
            // listener for when this tab is selected.
            actionBar.addTab(
                    actionBar.newTab()
                            .setText(mAppSectionsPagerAdapter.getPageTitle(i))
                            .setTabListener(this));
        }
    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
        // When the given tab is selected, switch to the corresponding page in the ViewPager.
        mViewPager.setCurrentItem(tab.getPosition());
    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction fragmentTransaction) {
    }

    /**
     * A {@link FragmentPagerAdapter} that returns a fragment corresponding to one of the primary
     * sections of the app.
     */
    public static class AppSectionsPagerAdapter extends FragmentPagerAdapter {

        public AppSectionsPagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int i){
            switch (i) {
                case 0:
                    // The first section of the app is the most interesting -- it offers
                    // a launchpad into the other demonstrations in this example application.
                    return new LaunchpadSectionFragment();

                case 1:
                    return new BluetoothClass();

                default:
                    // The GPS section of the app .
                    Fragment fragment = new DummySectionFragment();
                    Bundle args = new Bundle();
                    args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, i + 1);
                    fragment.setArguments(args);
                    return fragment;
                }
        }

        @Override
        public int getCount() {
            return 3;
        }

        @Override
        public String getPageTitle(int position) {
            if (position == 0 ){
                return "Welcome Page";
            }
            if (position == 1 ){
                return "Sensors";
            }

            return "GPS";
        }
    }

除此之外

蓝牙类

在 MainActivity 中找到

public static class BluetoothClass extends Fragment{
        public static final String ARG_SECTION_NUMBER = "section_number";
        /*
         * Bluetooth Class Variable definitions
         */
        Button button;
        ToggleButton toggle_discovery;
        ListView listView;
        BluetoothAdapter mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
        ArrayAdapter<String> mArrayAdapter;
        ArrayAdapter<String> adapter;
        ArrayList<String> pairedDevicesList;
        ArrayList<String> unpairedDevicesList;
        ArrayList<String> combinedDevicesList;
        Set<BluetoothDevice> pairedDevices;
        Set<String> unpairedDevices;
        BroadcastReceiver mReceiver;
        String selectedFromList;
        String selectedFromListName;
        String selectedFromListAddress;
        BluetoothDevice selectedDevice;
        ActionBarActivity aba = new ActionBarActivity();

        /* 
         * Important Bluetooth specific variables 
         * and other important data variables
         * 
         */
        protected static final int SUCCESS_CONNECT = 0;
        protected static final int MESSAGE_READ = 1;
        final int STATE_CONNECTED = 2;
        final int STATE_CONNECTING = 1;
        final int STATE_DISCONNECTED = 0;
        private final UUID MY_UUID = UUID.fromString("0001101-0000-1000-8000-00805F9B34FB");
        private static final int REQUEST_ENABLE_BT = 1;
        public byte[] completeData;


        /*
         * Bluetooth Handler Method
         */
        Handler mHandler = new Handler(){           
            public void handleMessage(Message msg){
                super.handleMessage(msg);
                switch(msg.what){
                    case SUCCESS_CONNECT:
                        // Do Something;
                        ConnectedThread connectedThread = new ConnectedThread((BluetoothSocket)msg.obj);
                        Toast.makeText(getActivity(),"CONNECTED",Toast.LENGTH_LONG).show();
                        //String s = "This string proves a socket connection has been established!!";
                        String s = "test";
                        connectedThread.write(s.getBytes());
                        connectedThread.start();
                        break;
                    case MESSAGE_READ:
                        byte[] readBuf = (byte[])msg.obj;
                        String string = new String(readBuf);
                        if (string.contains("!")){
                            //Do nothing!!
                        }else{
                            Toast.makeText(getActivity(),string,Toast.LENGTH_SHORT).show(); 
                        }


                break;
                }       
            }
        };

        public void onCreate(Bundle savedInstance){
            super.onCreate(savedInstance);
            enableBT(); 
            pairedDevicesList = new ArrayList<String>();
            unpairedDevicesList = new ArrayList<String>();
            unpairedDevices = new HashSet<String>();
        }

        public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
            View rootview = inflater.inflate(R.layout.bluetooth, container,false);
            Toast.makeText(getActivity(), "Fragment Created",Toast.LENGTH_SHORT).show();            
            rootview.findViewById(R.id.findDevices).setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    enableBT();
                    mArrayAdapter = new ArrayAdapter<String>(aba,android.R.layout.simple_list_item_1,removeDuplicates(unpairedDevicesList,pairedDevicesList));
                    pairedDevices = mBluetoothAdapter.getBondedDevices();
                    displayCominedDevices(mArrayAdapter);
                }
            });

            return rootview;
        }   

        public void onActivityCreared(Bundle savedInstanceState){
            super.onActivityCreated(savedInstanceState);
        }



        public void onStart(){
            super.onStart();
            Toast.makeText(getActivity(), "Fragment started",Toast.LENGTH_SHORT).show();
        }       

        public void onResume(){
            super.onStart();
            Toast.makeText(getActivity(), "Fragment Resumed",Toast.LENGTH_SHORT).show();

        }

        public void onStop(){
            super.onStart();
            Toast.makeText(getActivity(), "Fragment Stoped",Toast.LENGTH_SHORT).show();
            disableBT();
        }


        public void enableBT(){
            if (mBluetoothAdapter == null) {
                // Device does not support Bluetooth
                Toast.makeText(getActivity(), "Bluetooth is not suppourted on Device",Toast.LENGTH_SHORT).show();
            }

            if (!mBluetoothAdapter.isEnabled()) {
               Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
               startActivityForResult(enableBtIntent, REQUEST_ENABLE_BT);
               int resultCode = Activity.RESULT_OK;
                if(resultCode < 1){
                    Toast.makeText(getActivity(), "Please Accept Enabling Bluetooth Request!", Toast.LENGTH_LONG).show();
                }
                else{
                    Toast.makeText(getActivity(), "Enabling Bluetooth FAILED!", Toast.LENGTH_SHORT).show();
                }
            }
        }

        public void disableBT(){
            if (mBluetoothAdapter.isEnabled()){
                mBluetoothAdapter.disable();
            }
        }

        /*
         * Display Helper Methods
         */
        public void displayCominedDevices(ArrayAdapter<String> mArrayAdapter){
            displayPairedDevices();
            displayDetectedDevices();
            ActionBarActivity aba = new ActionBarActivity();
            listView = (ListView) getView().findViewById(R.id.listView); 
            //mArrayAdapter = new ArrayAdapter<String>(aba,android.R.layout.simple_list_item_1,removeDuplicates(unpairedDevicesList,pairedDevicesList));
            listView.setAdapter(mArrayAdapter);
        }


        public void displayPairedDevices(){
            // If there are paired devices
            enableBT();
            if (pairedDevices.size() > 0) {
                // Loop through paired devices
                for (BluetoothDevice device : pairedDevices) {
                    // Add the name and address to an array adapter to show in a ListView
                    String s = " ";
                    String deviceName = device.getName();
                    String deviceAddress = device.getAddress();
                    pairedDevicesList.add(deviceName + s + deviceAddress +" \n");
                }
            }
        }

        public void displayDetectedDevices(){
            mBluetoothAdapter.startDiscovery();

            // Create a BroadcastReceiver for ACTION_FOUND
            mReceiver = new BroadcastReceiver() {
                public void onReceive(Context context, Intent intent) {
                    String action = intent.getAction();
                    // When discovery finds a device
                    if(BluetoothDevice.ACTION_FOUND.equals(action)){
                        BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
                        String deviceName = device.getName();
                        String deviceAddress = device.getAddress();
                        String s = " ";
                        unpairedDevices.add(deviceName + s + deviceAddress +" \n");
                        unpairedDevicesList = new ArrayList<String>(unpairedDevices);
                    }
                }
            };
        }

        public ArrayList<String> removeDuplicates(ArrayList<String> s1, ArrayList<String> s2){
            combinedDevicesList =  new ArrayList<String>();
            combinedDevicesList.addAll(s1);
            combinedDevicesList.addAll(s2);
            Set Unique_set = new HashSet(combinedDevicesList);
            combinedDevicesList = new ArrayList<String>(Unique_set);
            /*Debugging 
            Toast.makeText(getApplication(),"Combined List" + combinedDevicesList.toString(),Toast.LENGTH_LONG).show(); */
            return combinedDevicesList;
        }


        /*
         * Bluetooth Connection Threads
         */

        public class ConnectThread extends Thread {
            private final BluetoothSocket mmSocket;
            private final BluetoothDevice mmDevice;
            public ConnectThread(BluetoothDevice device) {

                /*
                 *  Use a temporary object that is later assigned to mmSocket,
                 *  because mmSocket is final                
                 */

                BluetoothSocket tmp = null;

                mmDevice = device;

                // Get a BluetoothSocket to connect with the given BluetoothDevice
                try {
                    // MY_UUID is the app's UUID string, also used by the server code
                    tmp = device.createRfcommSocketToServiceRecord(MY_UUID);
                } catch (IOException e) { }
                mmSocket = tmp;
            }

            public void run() {
                // Cancel discovery because it will slow down the connection
                mBluetoothAdapter.cancelDiscovery();

                try {
                // Connect the device through the socket. This will block
                    // until it succeeds or throws an exception
                    mmSocket.connect();
                } catch (IOException connectException) {
                    // Unable to connect; close the socket and get out
                    try {
                        mmSocket.close();
                    } catch (IOException closeException) {
                        Toast.makeText(getActivity(), "Connecting to device failed!", Toast.LENGTH_LONG).show();
                    }
                        return;
                }

                    // Do work to manage the connection (in a separate thread)
                    mHandler.obtainMessage(SUCCESS_CONNECT, mmSocket).sendToTarget();
            }

            /** Will cancel an in-progress connection, and close the socket */
            public void cancel() {
                try {
                    mmSocket.close();
                   } catch (IOException e) { }
            }

        }

        private class ConnectedThread extends Thread {
            private final BluetoothSocket mmSocket;
            private final InputStream mmInStream;
            private final OutputStream mmOutStream;

            public ConnectedThread(BluetoothSocket socket) {
                mmSocket = socket;
                InputStream tmpIn = null;
                OutputStream tmpOut = null;

                // Get the input and output streams, using temp objects because
                // member streams are final
                try {
                    tmpIn = socket.getInputStream();
                    tmpOut = socket.getOutputStream();
                } catch (IOException e) { }

                mmInStream = tmpIn;
                mmOutStream = tmpOut;
            }

            public void run() {
                byte[] buffer; // buffer store for the stream
                int bytes; // bytes returned from read()

                // Keep listening to the InputStream until an exception occurs
                while (true) {
                    try {
                        // Read from the InputStream
                        buffer = new byte[9800];
                        bytes = mmInStream.read(buffer,0,buffer.length);

                        // Send the obtained bytes to the UI activity
                        mHandler.obtainMessage(MESSAGE_READ, bytes, -1, buffer).sendToTarget();
                    } catch (IOException e) {
                        break;
                    }
                }
            }

            /* Call this from the main activity to send data to the remote device */
            public void write(byte[] bytes) {
                try {
                    mmOutStream.write(bytes);


                } catch (IOException e) { }
            }
        }

    }

问题

所以一切正常，直到我单击位于我的应用程序上的蓝牙类 (bluetooth.xml) 文件中的 findDevices 按钮。

1. 根据 Logcat 当我尝试声明 mArrayAdapter 时出现问题。我不明白为什么我会收到错误，因为我在 fragment 的 onCreateView() 部分(在 onCreate() 部分之后)实现了 mArrayApapter 声明，所以 logCat 的错误没有意义。

Link to fragments android page

Answer 1

这里:

ActionBarActivity aba = new ActionBarActivity();

您正在尝试实例化一个 Activity!

不要那样做。在 Android 中启动 Activity 的方法是使用 startActivity 方法!

所以你实际上做了两次。但是你的 logcat 提示的似乎是第二个:你在 onClick 中调用这个: > 你不应该做的事情。