我正在使用netbeans中的处理来在一个ledstrip数组上播放电影，我正在使用OPC.class进行ledstrip fadecandy映射。此代码适用于处理草图，但是当我尝试在netbeans上使用它时，OPC.java的draw（）方法中的loadpixel（）会抛出一个nullpointer异常。
堆栈跟踪：
Exception in thread "Animation Thread" java.lang.NullPointerException
at processing.core.PApplet.loadPixels(PApplet.java:10625)
at com.processing.OPC.draw(OPC.java:139)
at com.processing.Video.draw(Video.java:62)
at processing.core.PApplet.handleDraw(PApplet.java:2402)
at processing.awt.PSurfaceAWT$12.callDraw(PSurfaceAWT.java:1527)
at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:316)
Video.java
public class Video extends PApplet
{
OPC opc;
Movie movie;
public static void main(String args[])
{
PApplet.main(new String[] { "--present", "com.processing.Video" });
}
public void settings()
{
size(600, 240);
}
public void setup()
{
opc = new OPC(this, "192.168.15.10", 7890);
for(int i=0; i<24; i++) {
opc.ledStrip(i * 60, 60,
300, i * 240 / 24 + 240 / 48, 240 / 24, PI, false);
}
movie = new Movie(this, "waffle.mp4");
movie.loop();
}
public void movieEvent(Movie m)
{
m.read();
}
@Override
public void draw()
{
if (movie.available() == true) {
movie.read();
}
image(movie, 0, 0, width, height);
}
}
OPC.java
public class OPC extends PApplet implements Runnable
{
Thread thread;
Socket socket;
OutputStream output, pending;
String host;
int port;
int height = 240;
int width = 600;
int[] pixelLocations;
byte[] packetData;
byte firmwareConfig;
String colorCorrection;
boolean enableShowLocations;
PApplet parent;
OPC(PApplet parent, String host, int port)
{
this.host = host;
this.port = port;
thread = new Thread(this);
thread.start();
this.enableShowLocations = true;
registerMethod("draw", this);
}
public void led(int index, int x, int y){
if (pixelLocations == null) {
pixelLocations = new int[index + 1];
} else if (index >= pixelLocations.length) {
pixelLocations = Arrays.copyOf(pixelLocations, index + 1);
}
pixelLocations[index] = x + 600 * y;
}
public void ledStrip(int index, int count, float x, float y, float spacing, float angle, boolean reversed)
{
float s = sin(angle);
float c = cos(angle);
for (int i = 0; i < count; i++) {
led(reversed ? (index + count - 1 - i) : (index + i),
(int)(x + (i - (count-1)/2.0) * spacing * c + 0.5),
(int)(y + (i - (count-1)/2.0) * spacing * s + 0.5));
}
}
void showLocations(boolean enabled)
{
enableShowLocations = enabled;
}
void setColorCorrection(String s)
{
colorCorrection = s;
sendColorCorrectionPacket();
}
void sendFirmwareConfigPacket()
{
if (pending == null) {
return;
}
byte[] packet = new byte[9];
packet[0] = (byte)0x00; // Channel (reserved)
packet[1] = (byte)0xFF; // Command (System Exclusive)
packet[2] = (byte)0x00; // Length high byte
packet[3] = (byte)0x05; // Length low byte
packet[4] = (byte)0x00; // System ID high byte
packet[5] = (byte)0x01; // System ID low byte
packet[6] = (byte)0x00; // Command ID high byte
packet[7] = (byte)0x02; // Command ID low byte
packet[8] = (byte)firmwareConfig;
try {
pending.write(packet);
} catch (Exception e) {
dispose();
}
}
void sendColorCorrectionPacket()
{
if (colorCorrection == null) {
return;
}
if (pending == null) {
return;
}
byte[] content = colorCorrection.getBytes();
int packetLen = content.length + 4;
byte[] header = new byte[8];
header[0] = (byte)0x00; // Channel (reserved)
header[1] = (byte)0xFF; // Command (System Exclusive)
header[2] = (byte)(packetLen >> 8); // Length high byte
header[3] = (byte)(packetLen & 0xFF); // Length low byte
header[4] = (byte)0x00; // System ID high byte
header[5] = (byte)0x01; // System ID low byte
header[6] = (byte)0x00; // Command ID high byte
header[7] = (byte)0x01; // Command ID low byte
try {
pending.write(header);
pending.write(content);
} catch (Exception e) {
dispose();
}
}
public void draw()
{
if (pixelLocations == null) {
return;
}
if (output == null) {
return;
}
int numPixels = pixelLocations.length;
int ledAddress = 4;
setPixelCount(numPixels);
println("pixel loading");
loadPixels();
println("pixel loaded123");
for (int i = 0; i < numPixels; i++) {
int pixelLocation = pixelLocations[i];
int pixel = pixels[pixelLocation];
packetData[ledAddress] = (byte)(pixel >> 16);
packetData[ledAddress + 1] = (byte)(pixel >> 8);
packetData[ledAddress + 2] = (byte)pixel;
ledAddress += 3;
if (true) {
pixels[pixelLocation] = 0xFFFFFF ^ pixel;
}
}
writePixels();
if (enableShowLocations) {
updatePixels();
print("a");
}
}
void setPixelCount(int numPixels)
{
int numBytes = 3 * numPixels;
int packetLen = 4 + numBytes;
if (packetData == null || packetData.length != packetLen) {
// Set up our packet buffer
packetData = new byte[packetLen];
packetData[0] = (byte)0x00;
packetData[1] = (byte)0x00;
packetData[2] = (byte)(numBytes >> 8);
packetData[3] = (byte)(numBytes & 0xFF);
}
}
void setPixel(int number, int c)
{
println("set");
int offset = 4 + number * 3;
if (packetData == null || packetData.length < offset + 3) {
setPixelCount(number + 1);
}
packetData[offset] = (byte) (c >> 16);
packetData[offset + 1] = (byte) (c >> 8);
packetData[offset + 2] = (byte) c;
}
int getPixel(int number)
{
println("get");
int offset = 4 + number * 3;
if (packetData == null || packetData.length < offset + 3) {
return 0;
}
return (packetData[offset] << 16) | (packetData[offset + 1] << 8) | packetData[offset + 2];
}
void writePixels()
{
println("write");
if (packetData == null || packetData.length == 0) {
return;
}
if (output == null) {
return;
}
try {
output.write(packetData);
} catch (Exception e) {
dispose();
}
}
public void dispose()
{
if (output != null) {
println("Disconnected from OPC server");
}
socket = null;
output = pending = null;
}
public void run()
{
println("?");
if(output == null) { // No OPC connection?
try { // Make one!
socket = new Socket(host, port);
socket.setTcpNoDelay(true);
pending = socket.getOutputStream();
println("Connected to OPC server");
sendColorCorrectionPacket();
sendFirmwareConfigPacket();
output = pending;
} catch (ConnectException e) {
dispose();
} catch (IOException e) {
dispose();
}
}
try {
Thread.sleep(500);
}
catch(InterruptedException e) {
}
}
}
答案 0 :(得分：0)
您应该只有一个扩展PApplet的类。
将该课程视为您的＆＃34;主要＆＃34;类。需要使用Processing函数的任何其他类都需要该主类的实例才能访问Processing函数。您可以使用this关键字传递它。
事实上，您已经这样做了 - 请注意您将this传递到OPC类，然后将其存储在parent参数中。你永远不会对该参数做任何事情。
所以第1步是要从extends PApplet课程中移除OBC：
public class OPC implements Runnable
这会导致一些编译错误。没关系，我们稍后会修复它们。
第2步是将PApplet parent参数实际存储在类级变量中。
OPC(PApplet parent, String host, int port){
this.parent = parent;
//rest of constructor
现在你有了，第3步是通过使用parent变量来访问处理函数来修复任何编译错误。
parent.println("pixel loading");
parent.loadPixels();
可以在Processing in eclipse tutorial中找到更多信息。它适用于日食，但同样的原则也适用于netbeans。