Android中的java.lang.NullPointerException

我面临的一个问题是关于NullPointerException我无法找到我的代码中的问题。请帮助我。Android中的java.lang.NullPointerException

java.lang.RuntimeException: Unable to start receiver me.radhakrishna.buddyreader.TextMessageReceiver: java.lang.NullPointerException 
at android.app.ActivityThread.handleReceiver(ActivityThread.java:2146) 
at android.app.ActivityThread.access$1500(ActivityThread.java:127) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1208) 
at android.os.Handler.dispatchMessage(Handler.java:99) 
at android.os.Looper.loop(Looper.java:137) 
at android.app.ActivityThread.main(ActivityThread.java:4441) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:511) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:823) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:590) 
at dalvik.system.NativeStart.main(Native Method) 
Caused by: java.lang.NullPointerException 
at me.radhakrishna.buddyreader.MainActivity.stopReading(MainActivity.java:81) 
at me.radhakrishna.buddyreader.TextMessageReceiver.onReceive(TextMessageReceiver.java:59) 
at android.app.ActivityThread.handleReceiver(ActivityThread.java:2139) 
... 10 more

我的清单文件：

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="me.radhakrishna.buddyreader" 
    android:versionCode="14" 
    android:versionName="1.2.2" > 

    <uses-permission android:name="android.permission.RECEIVE_SMS" /> 
    <uses-permission android:name="android.permission.READ_SMS" /> 
    <uses-permission android:name="android.permission.READ_CONTACTS" /> 
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED" /> 

    <uses-sdk 
     android:minSdkVersion="8" 
     android:targetSdkVersion="17" /> 

    <application 
     android:allowBackup="true" 
     android:icon="@drawable/ic_launcher" 
     android:label="@string/app_name" 
     android:theme="@style/AppTheme" > 
     <activity 
      android:name="me.radhakrishna.buddyreader.MainActivity" 
      android:label="@string/app_name" > 
      <intent-filter> 
       <action android:name="android.intent.action.MAIN" /> 
       <category android:name="android.intent.category.LAUNCHER" /> 
      </intent-filter> 
     </activity> 
     <activity 
      android:name="me.radhakrishna.buddyreader.MessageActivity" 
      android:label="@string/app_name" > 
     </activity> 
     <activity 
      android:name="me.radhakrishna.buddyreader.PreferActivity" 
      android:label="@string/app_name" > 
     </activity> 
     <receiver android:name="me.radhakrishna.buddyreader.TextMessageReceiver" android:exported="true"> 
      <intent-filter> 
       <action android:name="android.intent.action.BOOT_COMPLETED" /> 
       <action android:name="android.provider.Telephony.SMS_RECEIVED" /> 
      </intent-filter> 
     </receiver> 
    </application> 

</manifest>

我TextMessageReceiver.java文件：

package me.radhakrishna.buddyreader; 

import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.FileOutputStream; 
import java.io.IOException; 

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; 

public class TextMessageReceiver extends BroadcastReceiver{ 
    @Override 
    public void onReceive(Context context, Intent intent){ 

     if ("android.intent.action.BOOT_COMPLETED".equals(intent.getAction())) { 
      String val=""; 
      FileInputStream fileos; 
      try { 
       fileos = context.getApplicationContext().openFileInput("startup"); 
       byte[] input = new byte[fileos.available()]; 
       while(fileos.read(input) != -1){ 
        val += new String(input); 
       } 
       if(val.equals("ON")){ 
        Intent myIntent = new Intent(context, MainActivity.class); 
        myIntent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK); 
        context.startActivity(myIntent); 
       } 
       fileos.close(); 
      } catch (FileNotFoundException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } 

     Bundle bundle=intent.getExtras(); 
     Object[] messages=(Object[])bundle.get("pdus"); 
     SmsMessage[] sms=new SmsMessage[messages.length]; 

     for(int n=0;n<messages.length;n++){ 
      sms[n]=SmsMessage.createFromPdu((byte[]) messages[n]); 
     } 

     for(SmsMessage msg:sms){ 
      final String mobileNum = msg.getOriginatingAddress(); 
      Uri uri = Uri.withAppendedPath(PhoneLookup.CONTENT_FILTER_URI, Uri.encode(mobileNum));   
      Cursor cursor= context.getContentResolver().query(uri, new String[]{PhoneLookup.DISPLAY_NAME},null,null,null); 

      final MainActivity main = new MainActivity(); 
      main.stopReading(); 
      main.setSpeechSpeed(); 
      String messageFormat = "Message from "+mobileNum+". Message: "+msg.getMessageBody(); 
      FileOutputStream fos; 
      try { 
       fos = context.getApplicationContext().openFileOutput("lastmessage",Context.MODE_PRIVATE); 
       fos.write(messageFormat.toString().getBytes()); 
       fos.close(); 
      } catch (FileNotFoundException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 

      if (cursor.getCount()>0){ 
       cursor.moveToFirst(); 
       String contactName = cursor.getString(0); 
       cursor.close(); 

       String enteredText = "Excuse me sir, You got a message from "+contactName+". Message, "+msg.getMessageBody(); 
       String words = enteredText.toString(); 
       main.speakWords(words); 
      }else{ 
       String enteredText = "Excuse me sir, You got a message from "+mobileNum+". Message, "+msg.getMessageBody(); 
       String words = enteredText.toString(); 
       main.speakWords(words); 
      } 
     } 
    } 
}

在此先感谢。

来源

2013-03-19 Radhakrishna Rayidi

什么是TextMessageReceiver.java:59 – 2013-03-19 13:10:26

'最终MainActivity main = new MainActivity（）;'<<<这里你试图创建一个Activity实例来调用'stopReading'和'setSpeechSpeed'方法，因为Activity没有运行这就是为什么你得到'NullPointerException' – 2013-03-19 13:11:08

第58行：最终MainActivity main = new MainActivity（）; 第59行：main.stopReading（）; – 2013-03-19 13:12:15

请不要阅读活动中的函数，因为您不完全知道活动的时间。我几个月遇到过类似的问题。所以把函数写在一个普通的类中然后使用它。

来源

2013-03-19 13:34:18

当用户收到一条消息时，我想停止当前的阅读消息，然后设置文本到语音引擎的语速，这就是我使用它。 – 2013-03-19 13:44:16

你不能在班级而不是活动下使用它吗？ – 2013-03-19 14:06:51

是的，我可以创建一个类。谢谢你的协助。 – 2013-03-19 17:06:49

Android中的java.lang.NullPointerException

回答

相关问题