我喜欢在用户解锁手机时让应用程序启动服务。当我开始解锁手机时，什么也没有发生，当我登录应用程序时（登录后它将运行ThirdActivity.java），应用程序被强制停止。错误日志显示如下：
11-28 14:28:52.846: E/AndroidRuntime(6439): FATAL EXCEPTION: main
11-28 14:28:52.846: E/AndroidRuntime(6439): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.android.project/com.example.android.project.ThirdActivity}: java.lang.NullPointerException: println needs a message
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2205)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2240)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.ActivityThread.access$600(ActivityThread.java:139)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1262)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.os.Handler.dispatchMessage(Handler.java:99)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.os.Looper.loop(Looper.java:156)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.ActivityThread.main(ActivityThread.java:4987)
11-28 14:28:52.846: E/AndroidRuntime(6439): at java.lang.reflect.Method.invokeNative(Native Method)
11-28 14:28:52.846: E/AndroidRuntime(6439): at java.lang.reflect.Method.invoke(Method.java:511)
11-28 14:28:52.846: E/AndroidRuntime(6439): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
11-28 14:28:52.846: E/AndroidRuntime(6439): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
11-28 14:28:52.846: E/AndroidRuntime(6439): at dalvik.system.NativeStart.main(Native Method)
11-28 14:28:52.846: E/AndroidRuntime(6439): Caused by: java.lang.NullPointerException: println needs a message
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.util.Log.println_native(Native Method)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.util.Log.d(Log.java:138)
11-28 14:28:52.846: E/AndroidRuntime(6439): at com.example.android.project.ThirdActivity.onCreate(ThirdActivity.java:52)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.Activity.performCreate(Activity.java:4538)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1071)
11-28 14:28:52.846: E/AndroidRuntime(6439): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2161)
11-28 14:28:52.846: E/AndroidRuntime(6439): ... 11 more
在我添加以下代码之前，它照常运行：
intentFilter = new IntentFilter();
intentFilter.addAction(MyService.MY_ACTION);
registerReceiver(intentReceiver, intentFilter);
private BroadcastReceiver intentReceiver = new BroadcastReceiver() {...};
protected void displayNotification(){...}
有人对这个问题有什么建议吗？
这是 StartMyServiceAtBootReceiver.java
public class StartMyServiceAtBootReceiver extends BroadcastReceiver{
public void onReceive(Context context, Intent intent) {
if (intent.getAction().equals(Intent.ACTION_USER_PRESENT)) {
HttpTest(context);
}
}
public static boolean isNetworkAvailable( Context startMyServiceAtBootReceiver ) {
Context context = startMyServiceAtBootReceiver.getApplicationContext();
ConnectivityManager connectivity = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE);
if (connectivity == null) {
return false;
} else {
NetworkInfo[] info = connectivity.getAllNetworkInfo();
if (info != null) {
for (int i = 0; i < info.length; i++) {
if (info[i].getState() == NetworkInfo.State.CONNECTED) {
return true;
}
}
}
}
return false;
}
public static void HttpTest( final Context startMyServiceAtBootReceiver)
{
if(isNetworkAvailable( startMyServiceAtBootReceiver) ){
Intent start = new Intent(startMyServiceAtBootReceiver, MyService.class);
start.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startMyServiceAtBootReceiver.startService(start);
}
}
}
我的服务.java
public class MyService extends Service{
int counter = 0;
static final int UPDATE_INTERVAL = 15000;
private Timer timer = new Timer();
DefaultHttpClient httpclient;
HttpPost httppost;
String line,result;
HttpResponse response;
InputStream is;
BufferedReader reader;
StringBuilder sb;
final static String MY_ACTION = "MY_ACTION";
@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
public int onStartCommand(Intent intent, int flags, int startId){
doSomethingRepeatedly();
return START_STICKY;
}
private void doSomethingRepeatedly(){
timer.scheduleAtFixedRate(new TimerTask(){
public void run(){
// Log.d("MyService", String.valueOf(++counter));
try{
httpclient = new DefaultHttpClient();
httppost = new HttpPost("http://www.kryptoquest.com/testing/checking.php");
response = httpclient.execute(httppost);
is = response.getEntity().getContent();
}catch(Exception e){
Log.e("log_tag", "Error:"+e.toString());
}
//convert response to string
try{
reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
sb = new StringBuilder();
line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
Log.d("test",sb.toString());
is.close();
result = sb.toString();
Intent intent = new Intent();
intent.setAction(MY_ACTION);
intent.putExtra("DATAPASSED", result);
sendBroadcast(intent);
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
}
},10000,UPDATE_INTERVAL);
}
public void onDestroy(){
super.onDestroy();
if(timer != null){
timer.cancel();
}
Toast.makeText(this, "Service Destroyed", Toast.LENGTH_SHORT).show();
}
}
第三活动.java
public class ThirdActivity extends ListActivity{
Bundle b;
String user,line,result,datapassed;
DefaultHttpClient httpclient;
HttpPost httppost;
HttpResponse response;
InputStream is = null;
BufferedReader reader;
StringBuilder sb;
ArrayList<NameValuePair> nameValuePairs;
ListView lv;
IntentFilter intentFilter;
int notification = 1;
String str = "";
String[] data;
int dlength;
public void onCreate(Bundle savedInstancesState){
super.onCreate(savedInstancesState);
setContentView(R.layout.list_screen);
lv = (ListView) findViewById(android.R.id.list);
Log.d("dg",user);
getList();
intentFilter = new IntentFilter();
intentFilter.addAction(MyService.MY_ACTION);
registerReceiver(intentReceiver, intentFilter);
user = getIntent().getExtras().getString("user");
}
public void getList(){
new Thread(){
public void run(){
try{
httpclient = new DefaultHttpClient();
httppost = new HttpPost("http://www.kryptoquest.com/tracker/friendlist.php");
response = httpclient.execute(httppost);
is = response.getEntity().getContent();
}catch(Exception e){
Log.e("log_tag", "Error:"+e.toString());
}
//convert response to string
try{
reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
sb = new StringBuilder();
line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
Log.d("test",sb.toString());
is.close();
result = sb.toString();
final String[] friend = result.split("[*]");
runOnUiThread(new Runnable()
{
public void run(){
setListAdapter(new ArrayAdapter<String>(ThirdActivity.this,android.R.layout.simple_list_item_1,friend));
}
});
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
}
}.start();
}
private BroadcastReceiver intentReceiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
datapassed = intent.getStringExtra("DATAPASSED");
if(datapassed.length()>0){
data = datapassed.split("[*]");
dlength = data.length;
for(int i=0;i<dlength;i++){
if(i==dlength-1){
str += String.valueOf(data[i]);
}else{
str += String.valueOf(data[i]) + ",";
}
}
Log.d("dataServices",str);
displayNotification();
str = "";
}
}
};
protected void displayNotification(){
Intent i = new Intent(this,NotificationView.class);
i.putExtra("notification", notification);
i.putExtra("name",str);
Log.d("String",str);
PendingIntent pi = PendingIntent.getActivity(this, 0, i, PendingIntent.FLAG_UPDATE_CURRENT);
NotificationManager mnotis =(NotificationManager)getSystemService(NOTIFICATION_SERVICE);
Notification notis = new Notification(R.drawable.notices2,"Reminder:You have " + dlength + " new friend request",System.currentTimeMillis());
notis.setLatestEventInfo(this,"Friend Request", str + "has sent you a friend request",pi);
notis.vibrate = new long[]{100,250,100,500};
mnotis.notify(0, notis);
}
}