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我有一种方法尝试写入 AlarmReceiver 中 SD 卡上的文本文件。在我将它移到 AlarmReceiver 之前，该方法运行良好，但现在它在 Logcat 中因以下内容而崩溃：

09-11 10:36:44.395: D/AndroidRuntime(946): Shutting down VM
09-11 10:36:44.395: W/dalvikvm(946): threadid=1: thread exiting with uncaught exception         (group=0x409c01f8)
09-11 10:36:44.425: E/AndroidRuntime(946): FATAL EXCEPTION: main
09-11 10:36:44.425: E/AndroidRuntime(946): java.lang.RuntimeException: Unable to start receiver com.exercise.AndroidSYSinfo.AlarmReceiver: java.lang.NullPointerException
09-11 10:36:44.425: E/AndroidRuntime(946):  at android.app.ActivityThread.handleReceiver(ActivityThread.java:2126)
09-11 10:36:44.425: E/AndroidRuntime(946):  at android.app.ActivityThread.access$1500(ActivityThread.java:123)
09-11 10:36:44.425: E/AndroidRuntime(946):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1197)
09-11 10:36:44.425: E/AndroidRuntime(946):  at android.os.Handler.dispatchMessage(Handler.java:99)
09-11 10:36:44.425: E/AndroidRuntime(946):  at android.os.Looper.loop(Looper.java:137)
09-11 10:36:44.425: E/AndroidRuntime(946):  at android.app.ActivityThread.main(ActivityThread.java:4424)
09-11 10:36:44.425: E/AndroidRuntime(946):  at java.lang.reflect.Method.invokeNative(Native Method)
09-11 10:36:44.425: E/AndroidRuntime(946):  at java.lang.reflect.Method.invoke(Method.java:511)
09-11 10:36:44.425: E/AndroidRuntime(946):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
09-11 10:36:44.425: E/AndroidRuntime(946):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
09-11 10:36:44.425: E/AndroidRuntime(946):  at dalvik.system.NativeStart.main(Native Method)
09-11 10:36:44.425: E/AndroidRuntime(946): Caused by: java.lang.NullPointerException
09-11 10:36:44.425: E/AndroidRuntime(946):  at java.io.Writer.write(Writer.java:141)
09-11 10:36:44.425: E/AndroidRuntime(946):  at com.exercise.AndroidSYSinfo.AlarmReceiver.writeSD(AlarmReceiver.java:318)
09-11 10:36:44.425: E/AndroidRuntime(946):  at com.exercise.AndroidSYSinfo.AlarmReceiver.onReceive(AlarmReceiver.java:182)
09-11 10:36:44.425: E/AndroidRuntime(946):  at android.app.ActivityThread.handleReceiver(ActivityThread.java:2119)

这是相关代码：

  public void writeSD(Context context) 
 {
      //Toast.makeText(context,"Saving sdcardstats.txt..." , Toast.LENGTH_SHORT).show();
         //  
         // Write SDCard stats to file
         //
         try
           {
           FileOutputStream fOut1 = context.openFileOutput("sdcardstats.txt", Context.MODE_PRIVATE);
           OutputStreamWriter osw1 = new OutputStreamWriter(fOut1);       
           osw1.write(string);
           osw1.flush();
           osw1.close();    

           }
           catch (IOException ioe)
           {

           ioe.printStackTrace();
           } //end catch


 }  // end of writeSD()
4

1 回答 1

0

字符串不为空

这是失败的源代码片段，带有行号：

140    public void write(String str) throws IOException {
141        write(str, 0, str.length());
142    }

单个语句抛出 a的唯一NullPointerException方法是 if stris null。因此，虽然您可能认为stringis not null，但您的堆栈跟踪表明并非如此。

于 2012-09-11T12:38:45.023 回答