2

我在诺基亚 N95（不是我写的）上调试 J2ME（用 eclipse 编写）代码试图找到错误并打印出堆栈跟踪给了我这个：

  03:08:479 TSKR. Error:
  java.lang.NullPointerException:   0
 - java.lang.String.<init>(), bci=6
  - v.b(), bci=9
 - v.e(), bci=805
 - v.e(), bci=3

有人可以帮我理解吗？哪条线，在哪里寻找以及有没有办法理解它或至少获得一些有价值和有用的信息。谢谢

更新

对不起..这是引发错误的函数：

public void     bluetoothFileProcessBytes(){//--------tracing out of memory error
    try{

    partCurrentLoop++;          
    fileCurrentLoop++;

    debug("Loop " + fileCurrentLoop + " of " + fileTotalLoops);

    bluetoothUpdateBytes(fileDataString.length());  
    guiUpdateProgressBar(true, partCurrentLoop, partTotalLoops);

    // LOOP Step 2: If there is no byte[] created for storing the bytes, create it. 

    if (fileBytesIsEmpty) {

        if (partCurrentNumber == partTotalNumber)
        {
            fileBytes = new byte[fileSize % (loopsPerHttpComm * BYTES_PER_LOOP)];
        }
        else    fileBytes = new byte[loopsPerHttpComm * BYTES_PER_LOOP];                    


    }   
    fileBytesIsEmpty = false;


    //LOOP Step 3: fill in the byte array with data from StringBuffer


    for (int i = 0; i < fileDataString.length(); i++) 
    {
         j = i + (partCurrentLoop - 1) * BYTES_PER_LOOP;
         c = fileDataString.charAt(i);              
         fileBytes[j] = (byte) c;   
    }
    c=0;
    j=0;
    i=0;

    //LOOP Step 4: Send the email if the byte array is full with a new HttpComm Thread

    if ((fileCurrentLoop % loopsPerHttpComm == 0
            || fileCurrentLoop == fileTotalLoops) && checkHttpCommStatus()) {


        // update partName and httpCommStatus
        String partName = fileName + " .part " + partCurrentNumber;             

        httpCommStatus = HTTP_RUNNING;

        if (fileCurrentLoop == fileTotalLoops) {        // FILE_END                 
            debug("New HttpComm Thread: FILE END"); 

            httpCommUpdateBytes(fileBytes.length);//<===================remove
            httpCommSucceeded();//<====================================remove



    /*new Thread(new HttpFileEnd(this, fileBytes, toAddress, fromAddress, fromName, digidownMAC,    partName, fileName, fileSize, digidownSoftwareVersion, partCurrentNumber, //<===============uncomment
                    partTotalNumber, DigidownApp.textObject.getActiveLanguage())).start();*/


        } else {                                    // FILE_PART


            //debug("Step 5");//<--------------------------------------------------------------------------------<-remove
        debug("New HttpComm Thread: FILE PART: " + partName);
        debug(">>>>>SEEEENDIIIING!<<<<<<<<");//<===========remove
        httpCommUpdateBytes(fileBytes.length);//<================remove
        httpCommSucceeded();//<==============================remove

/*new Thread(new HttpFilePart(this, fileBytes, toAddress, fromAddress, fromName,//<===============uncomment
                    digidownMAC, partName, fileSize, digidownSoftwareVersion,
                    partCurrentNumber, DigidownApp.textObject.getActiveLanguage())).start();*/  


    // Updating the new partTotalLoops
    if (partCurrentNumber == partTotalNumber){
partTotalLoops = fileTotalLoops - (loopsPerHttpComm * (partCurrentNumber - 1));             
            } else partTotalLoops = loopsPerHttpComm;


            partCurrentNumber++;
            partCurrentLoop = 0;
        }
        fileBytesIsEmpty = true;
        }

    // Leave the loop if failed 
    if (!errorHandlerActivated) {

        if (fileCurrentLoop < fileTotalLoops)
        {

        try{
        bluetoothIOStream.getFileBytes();//-throws null pointer exception !
        }catch(RuntimeException  ea){debug("Wammaaa!!! " + ea.toString());
                      ea.printStackTrace();}

        }
        else if(fileCurrentLoop == fileTotalLoops && checkHttpCommStatus())
                    {   bluetoothIOStream.getFileEnd(); }
    }
    }



    catch(RuntimeException e1)
    {
    Alert alert = new Alert("Fckn error!", e1.toString(), null, null);
    alert.setTimeout(Alert.FOREVER);
    debug("Error:");
    System.err.println();
    e1.printStackTrace();
    //throw e1;

    }
}

..以及未混淆应用程序的堆栈跟踪；这次是空指针异常 // Leave the loop if failed：

02:57:382 TSKR. Loop 972 of 1349
02:57:383 BIOS. Rec 978
02:57:588 TSKR. Loop 973 of 1349
02:57:590 BIOS. Rec 979
02:57:815 TSKR. Wammaaa!!! java.lang.NullPointerException:   0
java.lang.NullPointerException:   0
 - java.lang.String.<init>(), bci=6
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.readLineAsString(), bci=9
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=844
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getFileBytes(), bci=3
 - net.digidown.m.digidown.TaskRunner.bluetoothFileProcessBytes(), bci=430
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=857
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getFileBytes(), bci=3
 - net.digidown.m.digidown.TaskRunner.bluetoothFileProcessBytes(), bci=430
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=857
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getFileBytes(), bci=3
 - net.digidown.m.digidown.TaskRunner.bluetoothFileProcessBytes(), bci=430
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=857
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getFileBytes(), bci=3
 - net.digidown.m.digidown.TaskRunner.bluetoothFileProcessBytes(), bci=430
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=857

像这样持续一段时间然后..：

 - net.digidown.m.digidown.TaskRunner.bluetoothDoCommand_file(), bci=227
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=829
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getFileSettings(), bci=9
 - net.digidown.m.digidown.TaskRunner.bluetoothTask(), bci=90
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=513
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getTask(), bci=2
 - net.digidown.m.digidown.TaskRunner.bluetoothTask(), bci=172
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=513
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getTask(), bci=2
 - net.digidown.m.digidown.TaskRunner.bluetoothConnected(), bci=89
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=444
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.getVariable(), bci=426
 - net.digidown.m.digidown.bluetooth.BluetoothIOStream.run(), bci=366
 - java.lang.Thread.run(), bci=11
03:01:211 TSKR. Finished Task
03:01:212 BIOS. Rec 6
03:01:356 BIOS. task = >
03:01:357 TSKR. :: Got Task: (0x3e)
03:01:358 TSKR.  
03:01:359 TSKR. ERROR HANDLER: 116 - Bluetooth communication error
03:01:389 BIOS. Initiated
03:01:389 BIOS. About to read
03:01:394 BIOS. Phone(InitiateDigidownError) received: '0x3e 0xea Data CK'
03:01:397 BIOS. About to writeLine 'error' 
03:01:468 BIOS. quitStatus = QUIT_STATUS
4

2 回答 2

2

你的问题似乎是混淆。

Eclipse 应用程序的构建过程可能使用 proguard 之类的工具来提高性能并减小将在现场部署的应用程序 .jar 文件的大小。

混淆所做的一件事是将类和方法名称重写为更小的名称，因此堆栈跟踪的最后 3 行完全难以理解。

您需要生成一个未混淆的 .jar 文件，以便在您想要调试应用程序时使用。
（至少在您发现仅在应用程序的混淆版本上发生的问题之前。它会发生）

Eclipse 应该允许您通过修改项目属性来关闭混淆（或将其降低到最低级别）。如果做不到这一点，手动和临时破解用于构建 .jar 文件的 ant .xml 文件就可以解决问题。

混淆参数应该包括您的 MIDlet 类的名称，这样它的 startApp() 方法就不会被重命名。

于 2013-07-29T16:22:56.840 回答
1

您的问题可以通过两种方式解决：

  1. 在没有混淆的情况下运行您的应用程序。所以输出显示了准确的方法名称。
  2. 输入System.out.println('method_name::sample_tag')你的方法和线路，问题可能来自他们。然后在输出中您可以跟踪您的执行，您可以找到问题发生的点。
于 2013-07-31T08:41:31.677 回答