Println需要一条消息

Question

我正在尝试以下应用程序，但是当我运行它时，出现异常“println需要一个消息”。任何人都可以帮忙。以下是课程。

Receiver类

package com.sms; 

import android.content.BroadcastReceiver; 
import android.content.Context; 
import android.content.Intent; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.Bundle; 
import android.provider.ContactsContract.PhoneLookup; 
import android.telephony.SmsMessage; 
import android.widget.Toast; 

public class SMSReceiver extends BroadcastReceiver 
{ 
    String name=null; 
    private Context mContext; 


    @Override 
    public void onReceive(Context context, Intent intent) 
    { 
     // TODO Auto-generated method stub 

     int n; 
     Bundle bundle = intent.getExtras(); 
     Object pdus[] = (Object[]) bundle.get("pdus"); 
     SmsMessage smsMessage[] = new SmsMessage[pdus.length]; 
     for (n = 0; n < pdus.length; n++) 
     { 
      smsMessage[n] = SmsMessage.createFromPdu((byte[]) pdus[n]); 
     } 
     // show first message 
     String sms1 = smsMessage[0].getMessageBody(); 
     String from = smsMessage[0].getOriginatingAddress(); 
     //String name = getDisplayNameFromPhoneNo(from); 
     Uri lookupUri = Uri.withAppendedPath(PhoneLookup.CONTENT_FILTER_URI, Uri.encode(from)); 
     Cursor c = context.getContentResolver().query(lookupUri, new String[]{PhoneLookup.DISPLAY_NAME}, null, null, null); 
     while(c.moveToNext()){ 
       /* If we find a match we put it in a String.*/ 
       name = c.getString(c.getColumnIndexOrThrow(PhoneLookup.DISPLAY_NAME)); 
       } 

     //Toast toast = Toast.makeText(context, "SMS Received from: " + from, Toast.LENGTH_LONG); 
     //toast.show(); 

     System.out.println("!!!!"+name); 
     //Toast.makeText(context, "name: " + name, Toast.LENGTH_LONG).show(); 
     Intent sIntent=new Intent(context,SMSTalk.class); 
      sIntent.putExtra("stringdata",name); 
      context.startService(sIntent); 

     /*SMSTalk smsTalk = new SMSTalk(); 
     smsTalk.readName(name);*/ 
     //context.startService(new Intent(context,SMSTalk.class)); 
    } 


} 

Service类

package com.sms; 

import java.util.Locale; 

import android.app.Service; 
import android.content.Context; 
import android.content.Intent; 
import android.os.Bundle; 
import android.os.IBinder; 
import android.speech.tts.TextToSpeech; 
import android.speech.tts.TextToSpeech.OnInitListener; 
import android.speech.tts.TextToSpeech.OnUtteranceCompletedListener; 
import android.widget.Toast; 

public class SMSTalk extends Service implements OnInitListener, OnUtteranceCompletedListener { 
     public static TextToSpeech mTts; 
     private String spokenText; 
     public String msg=null; 
     int flag=0; 
     String temp; 
     Context context; 

     @Override 
     public void onCreate() { 

      // This is a good place to set spokenText 
      System.out.println("SERVICE CREATED"); 
      //Toast.makeText(this,"...>>>"+msg,Toast.LENGTH_LONG).show(); 

     } 

     @Override 
     public int onStartCommand(final Intent intent, int flags, int startId) 
     { 
        mTts=new TextToSpeech(this, this);     
        String msg=intent.getStringExtra("stringdata"); 
        //Toast.makeText(this, "service starting "+ msg, Toast.LENGTH_SHORT).show(); 
        System.out.println("$$$***"+msg);  

         Toast.makeText(this, "service starting message from: "+ msg, Toast.LENGTH_SHORT).show(); 

         //mTts.speak(msg,0, null); 

      return START_STICKY;  

     }  

     @Override 
     public void onInit(final int status) { 

       // TODO Auto-generated method stub 
       if (status == TextToSpeech.SUCCESS) { 

          mTts.setLanguage(Locale.UK); 
          Toast.makeText(getApplicationContext(), "SUCCESSFULLY INITIALIZED",Toast.LENGTH_LONG).show(); 
          mTts.speak(msg,0, null); 
         } 
        } 


     @Override 
     public void onUtteranceCompleted(String uttId) { 
      stopSelf(); 
      System.out.println("onUtteranceCompleted"+msg); 
     } 

     @Override 
     public void onDestroy() { 
      if (mTts != null) { 
       mTts.stop(); 
       mTts.shutdown(); 
      } 
      super.onDestroy(); 
     } 

     @Override 
     public IBinder onBind(Intent arg0) { 
      return null; 
     } 

     /* public void readName(String temp) 
     { 
      msg=temp; 
      System.out.println("HHHHHHHHHHHHHHHHHHH"+msg); 
      mTts.speak(msg, TextToSpeech.QUEUE_ADD, null); 

     }*/ 

     } 

清单文件

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
     package="com.sms" 
     android:versionCode="1" 
     android:versionName="1.0"> 
    <application android:icon="@drawable/icon" android:label="@string/app_name"> 

     <receiver android:name=".SMSReceiver" android:enabled="true">    
      <intent-filter>     
      <action android:name="android.provider.Telephony.SMS_RECEIVED"/>    
      </intent-filter>   
      </receiver> 
      <service android:name=".SMSTalk" 


      ></service> 

    </application> 
    <uses-sdk android:minSdkVersion="5" />  
    <uses-permission android:name="android.permission.RECEIVE_SMS"></uses-permission> 
    <uses-permission android:name="android.permission.READ_CONTACTS"></uses-permission> 


</manifest> 

logcat的跟踪

09-16 15:35:19.015: ERROR/AndroidRuntime(1148): FATAL EXCEPTION: main 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148): java.lang.NullPointerException: println needs a message 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.util.Log.println_native(Native Method) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.util.Log.i(Log.java:158) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.speech.tts.TextToSpeech.speak(TextToSpeech.java:720) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at com.sms.SMSTalk.onInit(SMSTalk.java:56) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.speech.tts.TextToSpeech$1.onServiceConnected(TextToSpeech.java:451) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.app.LoadedApk$ServiceDispatcher.doConnected(LoadedApk.java:1064) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.app.LoadedApk$ServiceDispatcher$RunConnection.run(LoadedApk.java:1081) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.os.Handler.handleCallback(Handler.java:587) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.os.Handler.dispatchMessage(Handler.java:92) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.os.Looper.loop(Looper.java:123) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at android.app.ActivityThread.main(ActivityThread.java:3647) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at java.lang.reflect.Method.invokeNative(Native Method) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at java.lang.reflect.Method.invoke(Method.java:507) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597) 
09-16 15:35:19.015: ERROR/AndroidRuntime(1148):  at dalvik.system.NativeStart.main(Native Method) 

Answer 1

显然，当它执行下面的行尚未被初始化msg：

mTts.speak(msg,0, null); 

所以将其更改为

public String msg=null; 

这样：

public String msg=""; 

或取决于您想要做什么，请使用适当的内容对其进行初始化。