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