问题
I'm a complete noob when it comes to networking programming.
I'm getting the following error:
E/AndroidRuntime( 4095): Caused by: java.lang.IndexOutOfBoundsException: length=18, offset=0, buffer size=0
At the following line:
SocketAddress servaddr = udpChannel.receive(rcvHskBuf);
This is how I create the buffer
ByteBuffer rcvHskBuf = ByteBuffer.allocateDirect(packetSize);
For the sake of debugging I changed the argument (which can be changed in the app) from the default 1432 to 1432*20 as explained below.
How do I go about debugging this? I tried changing the allocateDirect() argument to 20 times larger than it was before, yet I still get this issue.
Here's the full error log:
02-27 22:28:01.739: E/AndroidRuntime(2753): FATAL EXCEPTION: AsyncTask #1
02-27 22:28:01.739: E/AndroidRuntime(2753): java.lang.RuntimeException: An error occured while executing doInBackground()
02-27 22:28:01.739: E/AndroidRuntime(2753): at android.os.AsyncTask$3.done(AsyncTask.java:278)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.util.concurrent.FutureTask.run(FutureTask.java:137)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.lang.Thread.run(Thread.java:856)
02-27 22:28:01.739: E/AndroidRuntime(2753): Caused by: java.lang.IndexOutOfBoundsException: length=18, offset=0, buffer size=0
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.net.DatagramPacket.setLengthOnly(DatagramPacket.java:234)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.net.DatagramPacket.setLength(DatagramPacket.java:222)
02-27 22:28:01.739: E/AndroidRuntime(2753): at libcore.io.IoBridge.postRecvfrom(IoBridge.java:528)
02-27 22:28:01.739: E/AndroidRuntime(2753): at libcore.io.IoBridge.recvfrom(IoBridge.java:516)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.nio.DatagramChannelImpl.receiveDirectImpl(DatagramChannelImpl.java:232)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.nio.DatagramChannelImpl.receive(DatagramChannelImpl.java:185)
02-27 22:28:01.739: E/AndroidRuntime(2753): at com.alu.wireless.puredata.PSConnection.UDPInitialization(PSConnection.java:315)
02-27 22:28:01.739: E/AndroidRuntime(2753): at com.alu.wireless.puredata.PSConnection.PSInitialization(PSConnection.java:73)
02-27 22:28:01.739: E/AndroidRuntime(2753): at com.alu.wireless.puredata.PureDataActivity$MyTask.doInBackground(PureDataActivity.java:262)
02-27 22:28:01.739: E/AndroidRuntime(2753): at com.alu.wireless.puredata.PureDataActivity$MyTask.doInBackground(PureDataActivity.java:1)
02-27 22:28:01.739: E/AndroidRuntime(2753): at android.os.AsyncTask$2.call(AsyncTask.java:264)
02-27 22:28:01.739: E/AndroidRuntime(2753): at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
02-27 22:28:01.739: E/AndroidRuntime(2753): ... 4 more
The weird thing is, the app prints the contents of the buffer just fine. Obviously the code that prints the contents of the buffer is situated after the line that caused the exception (line 315, written above, where I create the buffer).
Any hints or pointers would be greatly appreciated. Thanks in advance.
来源：https://stackoverflow.com/questions/15122603/indexoutofboundsexception-with-datagramchannel-receivebuf