Java — обработка — исключение BufferedOutputStream

Я незнакомец с Java, но я разрабатываю приложение с Processingи мне нужно просветление, пожалуйста.

Я бегу php server на 127.0.0.1:8080 в корне .pde ниже. все мое php scripts без ошибок, а также остальной код обработки.

после тщательного анализа я узнал, что ошибка в функции ниже.

что такое повышенное исключение при мне? и как я могу исправить код?

//(cont)

void postPicture(){
//load the saved image into an array of bytes
byte[] thisFile=loadBytes(fileName);

//open a new connection to the server
thisClient = new Client(this, "localhost", 80);
//make an HTTP POST request:
thisClient.write("POST " + pictureScriptUrl + " HTTP/1.1\n");
thisClient.write("Host: localhost\n");
//tell the server you're sending the POST in multiple parts
//and send a unique string that will delineate the parts
thisClient.write("Content-Type: multipart/form-data; boundary=");
thisClient.write(boundary + "\n");

//form the beginning of the request
String requestHead ="--" + boundary + "\n";
requestHead +="Content-Disposition: form-data; name=\"file\"; ";
requestHead += "filename=\"" + fileName + "\"\n";
requestHead +="Content-Type: image/jpeg\n\n";

//form the end of the request
String tail="\n\n--" + boundary + "--\n";

//calculate and send the length of the total request
//including the head of the request, the file, and the tail
int contentLength = requestHead.length() + thisFile.length + tail.length();
thisClient.write("Content-Length: " + contentLength + "\n\n");

//send the header of the request, the file and the tail
thisClient.write(requestHead);
thisClient.write(thisFile);
thisClient.write(tail);
}

java.lang.NullPointerException
at java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:82)
at java.io.BufferedOutputStream.flush(BufferedOutputStream.java:140)
at javax.imageio.stream.FileCacheImageOutputStream.close(FileCacheImageOutputStream.java:238)
at com.sun.imageio.stream.StreamCloser$CloseAction.performAction(StreamCloser.java:130)
at com.sun.imageio.stream.StreamCloser$1.run(StreamCloser.java:74)
at java.lang.Thread.run(Thread.java:745)