我正在使用我的arduino uno和HC-05蓝牙模块创建家庭自动化Android应用程序。一切都很好。它可以扫描，连接，打开/关闭蓝牙，使用按钮和开关控制来打开和关闭灯泡。
我最大的问题是，当应用程序尚未连接到我的蓝牙模块时，如果单击开关控件，它会停止并自动结束应用程序。我一直在努力修复错误，但仍然没有发生任何事情。在此先感谢那些对此有所了解的人。
以下是LogCat中列出的内容：
03-02 00:02:48.807: E/AndroidRuntime(13767): FATAL EXCEPTION: main
03-02 00:02:48.807: E/AndroidRuntime(13767): java.lang.NullPointerException
03-02 00:02:48.807: E/AndroidRuntime(13767): at com.example.javac101.BluetoothCommandService.write(BluetoothCommandService.java:222)
03-02 00:02:48.807: E/AndroidRuntime(13767): at com.example.javac101.ControllerTab.sendData(ControllerTab.java:390)
03-02 00:02:48.807: E/AndroidRuntime(13767): at com.example.javac101.ControllerTab.onCheckedChanged(ControllerTab.java:271)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.widget.CompoundButton.setChecked(CompoundButton.java:126)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.widget.Switch.setChecked(Switch.java:666)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.widget.CompoundButton.toggle(CompoundButton.java:87)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.widget.CompoundButton.performClick(CompoundButton.java:99)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.view.View$PerformClick.run(View.java:17476)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.os.Handler.handleCallback(Handler.java:800)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.os.Handler.dispatchMessage(Handler.java:100)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.os.Looper.loop(Looper.java:194)
03-02 00:02:48.807: E/AndroidRuntime(13767): at android.app.ActivityThread.main(ActivityThread.java:5371)
03-02 00:02:48.807: E/AndroidRuntime(13767): at java.lang.reflect.Method.invokeNative(Native Method)
03-02 00:02:48.807: E/AndroidRuntime(13767): at java.lang.reflect.Method.invoke(Method.java:525)
03-02 00:02:48.807: E/AndroidRuntime(13767): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
03-02 00:02:48.807: E/AndroidRuntime(13767): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
03-02 00:02:48.807: E/AndroidRuntime(13767): at dalvik.system.NativeStart.main(Native Method)
可能不太清楚，所以这里是我的BluetoothCommandService中的代码：
package com.example.javac101;
import java.util.UUID;
import java.io.BufferedInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothServerSocket;
import android.bluetooth.BluetoothSocket;
import android.bluetooth.BluetoothDevice;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
public class BluetoothCommandService {
private final BluetoothAdapter BTAdapter;
private final Handler bluetoothHandler;
private static int connectionState;
private ConnectThread connectThread;
//private ConnectedThread connectedThread;
public static ConnectedThread connectedThread;
private AcceptThread mainAcceptThread;
public static final int stateNothing = 0; //doing nothing
public static final int stateListen = 1; //listening for incoming connections
public static final int stateConnecting = 2; //initiating an outgoing connection
public static final int stateConnected = 3;
//constants that indicate command to computer
public static final int exitCMD = -1;
public static final int VOL_UP = 1;
public static final int VOL_DOWN = 2;
private static final boolean D = true;
private static final String tagState = "BluetoothCommandService";
private static final UUID myUUID = UUID.fromString("fa87c0d0-afac-11de-8a39-0800200c9a66");
private static final String name = "BluetoothCommand";
private static final String BluetoothCommandService = null;
public BluetoothCommandService(Context context, Handler handler) { // context == UI Activity Context && handler == send message back to the UI Activity
BTAdapter = BluetoothAdapter.getDefaultAdapter();
connectionState = stateNothing;
bluetoothHandler = handler;
}
private synchronized void setState(int state) { // state == current connection state; an integer
if (D) Log.d(tagState, "setState() " + connectionState + " -> " + state);
connectionState = state;
bluetoothHandler.obtainMessage(ControllerTab.MESSAGE_STATE_CHANGE, state, -1).sendToTarget();
}
public synchronized int getState() { //return the current connection state
return connectionState;
}
public synchronized void start() {
if (D) Log.d(tagState, "start");
// Cancel any thread attempting to make a connection
if (connectThread != null)
{
connectThread.cancel();
connectThread = null;
}
// Cancel any thread currently running a connection
if (connectedThread != null)
{
connectedThread.cancel();
connectedThread = null;
}
// Start the thread to listen on a BluetoothServerSocket
if (mainAcceptThread == null)
{
mainAcceptThread = new AcceptThread();
mainAcceptThread.start();
}
setState(stateListen);
}
//device == the BluetoothDevice to connect
public synchronized void connect(BluetoothDevice device) {
if (D) Log.d(tagState, "connect to: " + device);
// Cancel any thread attempting to make a connection
if (connectionState == stateConnecting) {
if (connectThread != null)
{
connectThread.cancel();
connectThread = null;
}
}
// Cancel any thread currently running a connection
if (connectedThread != null)
{
connectedThread.cancel();
connectedThread = null;
}
// Cancel the accept thread because we only want to connect to one device
if (mainAcceptThread != null)
{
mainAcceptThread.cancel();
mainAcceptThread = null;
}
// Start the thread to connect with the given device
connectThread = new ConnectThread(device);
connectThread.start();
setState(stateConnecting);
}
public synchronized void connected(BluetoothSocket socket, BluetoothDevice device) {
if (D) Log.d(tagState, "connected");
// Cancel the thread that completed the connection
if (connectThread != null)
{
connectThread.cancel();
connectThread = null;
}
// Cancel any thread currently running a connection
if (connectedThread != null)
{
connectedThread.cancel();
connectedThread = null;
}
if (mainAcceptThread != null)
{
mainAcceptThread.cancel();
mainAcceptThread = null;
}
// Start the thread to manage the connection and perform transmissions
connectedThread = new ConnectedThread(socket);
connectedThread.start();
// Send the name of the connected device back to the UI Activity
Message msg = bluetoothHandler.obtainMessage(ControllerTab.MESSAGE_DEVICE_NAME);
Bundle bundle = new Bundle();
bundle.putString(ControllerTab.DEVICENAME, device.getName());
msg.setData(bundle);
bluetoothHandler.sendMessage(msg);
setState(stateConnected);
}
public synchronized void stop() {
if (D) Log.d(tagState, "stop");
if (connectThread != null)
{
connectThread.cancel();
connectThread = null;
}
if (connectedThread != null)
{
connectedThread.cancel();
connectedThread = null;
}
if (mainAcceptThread != null)
{
mainAcceptThread.cancel();
mainAcceptThread = null;
}
setState(stateNothing);
}
public static void write(byte[] out) {
// Create temporary object
ConnectedThread r;
r = connectedThread;
r.write(out);
}
public void write(int out) {
// Create temporary object
ConnectedThread r;
// Synchronize a copy of the ConnectedThread
synchronized (this) {
if (connectionState != stateConnected) return;
r = connectedThread;
}
// Perform the write unsynchronized
r.write(out);
}
private void connectionFailed() {
setState(stateListen);
// Send a failure message back to the Activity
Message msg = bluetoothHandler.obtainMessage(ControllerTab.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(ControllerTab.TOAST, "Unable to connect device");
msg.setData(bundle);
bluetoothHandler.sendMessage(msg);
}
private void connectionLost() {
setState(stateListen);
// Send a failure message back to the Activity
Message msg = bluetoothHandler.obtainMessage(ControllerTab.MESSAGE_TOAST);
Bundle bundle = new Bundle();
bundle.putString(ControllerTab.TOAST, "Device connection was lost");
msg.setData(bundle);
bluetoothHandler.sendMessage(msg);
}
public class ConnectThread extends Thread {
public final BluetoothSocket connectThread_socket;
public final BluetoothDevice connectThread_device;
public ConnectThread(BluetoothDevice device) {
connectThread_device = device;
BluetoothSocket tmp = null;
//Get a BluetoothSocket for a connection w/ the given BT device
//try {
//tmp = device.createRfcommSocketToServiceRecord(myUUID);} //ready to start a secure outgoing connection to this remote device using SDP lookup of uuid
//catch (IOException e) {
//Log.e(tag, msg, tr)
//Log.e(tagState, "create() failed", e);}
//Added 12/28/13
Method m;
try {
m = device.getClass().getMethod("createRfcommSocket", new Class[] {int.class});
tmp = (BluetoothSocket) m.invoke(device, 1);
} catch (SecurityException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (NoSuchMethodException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
} catch (IllegalArgumentException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (InvocationTargetException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
connectThread_socket = tmp;
}
public void run() {
Log.i(tagState, "BEGIN ConnectThread");
setName("ConnectThread");
// Always cancel discovery because it will slow down a connection
BTAdapter.cancelDiscovery();
// Make a connection to the BluetoothSocket
try {
connectThread_socket.connect();}
catch (IOException e) {
connectionFailed();
// Close the socket
try {
connectThread_socket.close();
} catch (IOException e2) {
Log.e(tagState, "Unable to close() socket during connection failure", e2);
}
// Start the service over to restart listening mode
BluetoothCommandService.this.start();
return;
}
// Reset the ConnectThread because we're done
synchronized (BluetoothCommandService.this) {
connectThread = null;
}
// Start the connected thread
connected(connectThread_socket, connectThread_device); //ERROR: will still create "connected"
}
public void cancel() {
try {
connectThread_socket.close();
} catch (IOException e) {
Log.e(tagState, "close() of connect socket failed", e);
}
}
}
public class ConnectedThread extends Thread {
public final BluetoothSocket connectedThread_socket;
public final InputStream connectedThread_inStream;
public final OutputStream connectedThread_outStream;
public ConnectedThread(BluetoothSocket socket) {
Log.d(tagState, "create ConnectedThread");
connectedThread_socket = socket;
InputStream tmpIn = null;
OutputStream tmpOut = null;
// Get the BluetoothSocket input and output streams
try {
tmpIn = socket.getInputStream();
tmpOut = socket.getOutputStream();
} catch (IOException e) {
Log.e(tagState, "temp sockets not created", e);
}
connectedThread_inStream = tmpIn;
connectedThread_outStream = tmpOut;
}
public void run() {
Log.i(tagState, "BEGIN ConnectedThread");
//BufferedInputStream bis = new BufferedInputStream(fis, 8 * 128);
byte[] buffer = new byte[1024]; // WALA JUD KO KASABOT ANI MAN :D
//buffer == the bytes to write
//buffer store for the stream
// Keep listening to the InputStream while connected
while (true) {
try {
// Read from the InputStream
int bytes = connectedThread_inStream.read(buffer);
//BufferedInputStream bis = new BufferedInputStream(fis, 8 * 128);
// int bytes = new BufferedInputStream(null, 8 * 128).read(buffer);
// Send the obtained bytes to the UI Activity
bluetoothHandler.obtainMessage(ControllerTab.MESSAGE_READ, bytes, -1, buffer)
.sendToTarget();
} catch (IOException e) {
Log.e(tagState, "disconnected", e);
connectionLost(); //ERROR: will still create "private void CONNECTIONLOST"
break;
}
}
}
public void write(byte[] buffer) {
try {
connectedThread_outStream.write(buffer);
} catch (IOException e) {
Log.e(tagState, "Exception during write", e);
}
}
public void write(int out) {
try {
connectedThread_outStream.write(out);
} catch (IOException e) {
Log.e(tagState, "Exception during write", e);
}
}
public void cancel() {
try {
connectedThread_outStream.write(exitCMD);
connectedThread_socket.close();
} catch (IOException e) {
Log.e(tagState, "close() of connect socket failed", e);
}
}
}
private class AcceptThread extends Thread {
// The local server socket
private final BluetoothServerSocket acceptThread_ServerSocket;
public AcceptThread() {
BluetoothServerSocket tmp = null;
// Create a new listening server socket
try {
tmp = BTAdapter.listenUsingRfcommWithServiceRecord(name, myUUID);
} catch (IOException e) {
Log.e(tagState, "listen() failed", e);
}
acceptThread_ServerSocket = tmp;
}
public void run() {
if (D) Log.d(tagState, "BEGIN mainAcceptThread" + this);
setName("AcceptThread");
BluetoothSocket socket = null;
// Listen to the server socket if we're not connected
while (connectionState != stateConnected) {
try {
// This is a blocking call and will only return on a
// successful connection or an exception
socket = acceptThread_ServerSocket.accept();
} catch (IOException e) {
Log.e(tagState, "accept() failed", e);
break;
}
// If a connection was accepted
if (socket != null) {
synchronized (BluetoothCommandService.this) {
switch (connectionState) {
case stateListen:
case stateConnecting:
// Situation normal. Start the connected thread.
connected(socket, socket.getRemoteDevice());
break;
case stateNothing:
case stateConnected:
// Either not ready or already connected. Terminate new socket.
try {
socket.close();
} catch (IOException e) {
Log.e(tagState, "Could not close unwanted socket", e);
}
break;
}
}
}
}
if (D) Log.i(tagState, "END mainAcceptThread");
}
public void cancel() {
if (D) Log.d(tagState, "cancel " + this);
try {
acceptThread_ServerSocket.close();
} catch (IOException e) {
Log.e(tagState, "close() of server failed", e);
}
}
}
}
这是我的ControllerTab第390行所在位置：
private void sendData(String message) throws IOException
{
byte[] msgBuffer = message.getBytes();
Log.d(tagStateCTRL, "...Sending data: " + message + "...");
BluetoothCommandService.write(msgBuffer);
}
如果r的值确实是问题，我应该分配给它的是不会为空？
答案 0 :(得分：0)
为了使用write的{{1}}方法，您应首先实例化BluetoothCommandService实例，然后调用其BluetoothCommandService方法，以便它应分配新的connect()实例到ConnectThread变量，而不是从connectThread
write()方法