我是Java的新手，我收到这个错误，我可以设法了解它的来源。我正在进行FFT分析，我收到了错误：
java.lang.ArrayIndexOutOfBoundsException: 66,
at DrawingFunction.main(DrawingFunction.java:66)
at AnimationGen.begin(AnimationGen.java:54)
at FFTclass.main2(FFTclass.java:213)
at fftTry.main(fftTry.java:34)
代码是fft的代码：
public static void main(String[] args) {
final String NEWLINE = "\n";
String inputFile = "C:/Users/USER/Downloads/DD.wav"; // Place the wav file in the top level directory, ie S:/input.wav
File fileLocation = new File(inputFile);
System.out.println("START");
try {
double[] complexNumber = readFully(fileLocation);
System.out.println(NEWLINE + "Read file");
double[] realPart = complexNumber;
double[] imagPart = new double[realPart.length];
System.out.println("Length = " + realPart.length);
FFTclass FFT = new FFTclass(1024);
FFT.main2(realPart,imagPart,1024);
//for (int i = 0; i < complexNumber.length; ++i) {
// System.out.println(complexNumber[i]);
//}
} catch (Exception ex) {
ex.printStackTrace();
}
}
static double[] readFully(File file) throws UnsupportedAudioFileException, IOException {
AudioInputStream in = AudioSystem.getAudioInputStream(file);
AudioFormat fmt = in.getFormat();
double sampleRate = fmt.getSampleRate();
double frameSize = fmt.getFrameSize();
double auidioDuration = fmt.getFrameRate();
double channels = fmt.getChannels();
System.out.println("File length = " + file.length() + " ");
System.out.println("Sample Rate = " + sampleRate + " per second");
System.out.println("Frame size = " + frameSize + " per second");
System.out.println("Frame rate = " + auidioDuration + " per second");
System.out.println("Channels = " + channels);
System.out.println("Length in time = " + (file.length()/frameSize * auidioDuration) + " seconds");
System.out.println("Length in time in minutes = " + (int)(file.length()/(frameSize* auidioDuration *60)) + " minutes and " + ( (file.length()/(frameSize* auidioDuration *60))- (int)(file.length()/(frameSize* auidioDuration *60)) )* 60 + " seconds");
byte[] bytes;
try {
if (fmt.getEncoding() != Encoding.PCM_SIGNED) {
throw new UnsupportedAudioFileException();
}
// read the data fully
bytes = new byte[in.available()];
in.read(bytes);
} finally {
in.close();
}
int bits = fmt.getSampleSizeInBits();
double max = Math.pow(2, bits - 1);
ByteBuffer bb = ByteBuffer.wrap(bytes);
bb.order(fmt.isBigEndian() ?
ByteOrder.BIG_ENDIAN : ByteOrder.LITTLE_ENDIAN);
double[] samples = new double[bytes.length * 8 / bits];
// convert sample-by-sample to a scale of
// -1.0 <= samples[i] < 1.0
for (int i = 0; i < samples.length; ++i) {
switch (bits) {
case 8:
samples[i] = (bb.get() / max);
break;
case 16:
samples[i] = (bb.getShort() / max);
break;
case 32:
samples[i] = (bb.getInt() / max);
break;
case 64:
samples[i] = (bb.getLong() / max);
break;
default:
throw new UnsupportedAudioFileException();
}
}
return samples;
}
对于FFT类：
int n, m;
// Lookup tables. Only need to recompute when size of FFT changes.
double[] cos;
double[] sin;
double[] window;
public FFTclass(int n) {
this.n = n;
this.m = (int)(Math.log(n) / Math.log(2));
// Make sure n is a power of 2
if(n != (1<<m))
throw new RuntimeException("FFT length must be power of 2");
// precompute tables
cos = new double[n/2];
sin = new double[n/2];
// for(int i=0; i<n/4; i++) {
// cos[i] = Math.cos(-2*Math.PI*i/n);
// sin[n/4-i] = cos[i];
// cos[n/2-i] = -cos[i];
// sin[n/4+i] = cos[i];
// cos[n/2+i] = -cos[i];
// sin[n*3/4-i] = -cos[i];
// cos[n-i] = cos[i];
// sin[n*3/4+i] = -cos[i];
// }
for(int i=0; i<n/2; i++) {
cos[i] = Math.cos(-2*Math.PI*i/n);
sin[i] = Math.sin(-2*Math.PI*i/n);
}
makeWindow();
}
protected void makeWindow() {
// Make a blackman window:
// w(n)=0.42-0.5cos{(2*PI*n)/(N-1)}+0.08cos{(4*PI*n)/(N-1)};
window = new double[n];
for(int i = 0; i < window.length; i++)
window[i] = 0.42 - 0.5 * Math.cos(2*Math.PI*i/(n-1))
+ 0.08 * Math.cos(4*Math.PI*i/(n-1));
}
public double[] getWindow() {
return window;
}
/***************************************************************
00089 * fft.c
00090 * Douglas L. Jones
00091 * University of Illinois at Urbana-Champaign
00092 * January 19, 1992
00093 * http://cnx.rice.edu/content/m12016/latest/
00094 *
00095 * fft: in-place radix-2 DIT DFT of a complex input
00096 *
00097 * input:
00098 * n: length of FFT: must be a power of two
00099 * m: n = 2**m
00100 * input/output
00101 * x: double array of length n with real part of data
00102 * y: double array of length n with imag part of data
00103 *
00104 * Permission to copy and use this program is granted
00105 * as long as this header is included.
00106 ****************************************************************/
public void fft(double[] x, double[] y)
{
int i,j,k,n1,n2,a;
double c,s,e,t1,t2;
// Bit-reverse
j = 0;
n2 = n/2;
for (i=1; i < n - 1; i++) {
n1 = n2;
while ( j >= n1 ) {
j = j - n1;
n1 = n1/2;
}
j = j + n1;
if (i < j) {
t1 = x[i];
x[i] = x[j];
x[j] = t1;
t1 = y[i];
y[i] = y[j];
y[j] = t1;
}
}
// FFT
n1 = 0;
n2 = 1;
for (i=0; i < m; i++) {
n1 = n2;
n2 = n2 + n2;
a = 0;
for (j=0; j < n1; j++) {
c = cos[a];
s = sin[a];
a += 1 << (m-i-1);
for (k=j; k < n; k=k+n2) {
t1 = c*x[k+n1] - s*y[k+n1];
t2 = s*x[k+n1] + c*y[k+n1];
x[k+n1] = x[k] - t1;
y[k+n1] = y[k] - t2;
x[k] = x[k] + t1;
y[k] = y[k] + t2;
}
}
}
}
// Test the FFT to make sure it's working
public static void main2(double[] re, double[] im, int N) {
FFTclass fft = new FFTclass(N);
double[] window = fft.getWindow();
double[] ang;
double[] amplitude;
// Impulse
re[0] = 1; im[0] = 0;
for(int i=1; i<N; i++)
re[i] = im[i] = 0;
System.out.println("Impulse");
beforeAfter(fft, re, im);
// Nyquist
for(int i=0; i<N; i++) {
re[i] = Math.pow(-1, i);
im[i] = 0;
}
System.out.println("Nyquist");
beforeAfter(fft, re, im);
// Single sin
for(int i=0; i<N; i++) {
re[i] = Math.cos(2*Math.PI*i / N);
im[i] = 0;
}
System.out.println("Single sin");
beforeAfter(fft, re, im);
// Ramp
for(int i=0; i<N; i++) {
re[i] = i;
im[i] = 0;
}
System.out.println("Ramp");
beforeAfter(fft, re, im);
amplitude = new double[re.length];
ang = new double[re.length];
for(int i=0; i<re.length;i++)
{
amplitude[i] = Math.sqrt( (re[i]*re[i])+ (im[i]*im[i]) );
//Calculate and return the phase
// angle in degrees.
if(im[i] == 0.0 && re[i] == 0.0){ang[i] = 0.0;}
else{ang[i] = Math.atan(im[i]/re[i])*180.0/Math.PI;}
if(re[i] < 0.0 && im[i] == 0.0){ang[i] = 180.0;}
else if(re[i] < 0.0 && im[i] == -0.0){
ang[i] = -180.0;}
else if(re[i] < 0.0 && im[i] > 0.0){
ang[i] += 180.0;}
else if(re[i] < 0.0 && im[i] < 0.0){
ang[i] += -180.0;}
}
for(int i = 100500; i<100600; i++)
{
System.out.print( '\n' + "Magnitude["+i+"] = " +amplitude[i]+ ", ");
System.out.print( '\n' + "Angle phase["+i+"] = " +ang[i]+ ", ");
}
long time = System.currentTimeMillis();
double iter = 30000;
for(int i=0; i<iter; i++)
fft.fft(re,im);
time = System.currentTimeMillis() - time;
System.out.println("\n" + "Averaged " + (time/iter) + "ms per iteration");
System.out.println("Time: " + (time) + "ms");
AnimationGen animation = new AnimationGen();
animation.begin(amplitude);
}
protected static void beforeAfter(FFTclass fft, double[] re, double[] im) {
System.out.println("Before: ");
printReIm(re, im);
fft.fft(re, im);
System.out.println("After: ");
printReIm(re, im);
}
protected static void printReIm(double[] re, double[] im) {
System.out.print("Re: [");
//for(int i=0; i<re.length; i++)
System.out.println("i = " + re.length);
for(int i=100550; i<100650; i++)
System.out.print(((int)(re[i]*1000)/1000.0) + " ");
System.out.print("]\nIm: [");
//for(int i=0; i<im.length; i++)
for(int i=100550; i<100650; i++)
System.out.print(((int)(im[i]*1000)/1000.0) + " ");
System.out.println("]");
}
动画源：
public int frameWidth = 1920;
public int frameHeigth = 1080;
public int fps = 30;
public void begin(double[] magnitude)
{
int magnitudeLength = magnitude.length;
int value = (int)magnitudeLength/44100;
double [][][] magnitudesPerSecond = new double[value][fps][(int)44100/fps];
for(int i = 0; i < value;i++) {
for(int j = 0; j < fps;j++) {
for (int k = 0; k < (int)44100/fps; k++) {
int arraynumber = k + (j*fps) +(i * (int)44100/fps);
magnitudesPerSecond[i][j][k] = magnitude[arraynumber];
}
}
}
System.out.println("i = " + magnitudesPerSecond.length);
System.out.println("j = " + magnitudesPerSecond[0].length);
System.out.println("k = " + magnitudesPerSecond[0][0].length);
DrawingFunction DF = new DrawingFunction();
DF.main(value, fps, magnitudesPerSecond);
}
最后的DrawingFunction
public int second = 0;
Timer t = new Timer();
TimerTask timeTask = new TimerTask() {
@Override
public void run() {
second++;
}
};
public double addingAngle = 0;
public int frameWidth = 1920;
public int frameHeigth = 1080;
public int value;
public int fps;
public double[][][] magnitude;
double xPoint[][][];
double yPoint[][][];
public void main(int value, int fps, double[][][] magnitude) {
this.value = value;
this.fps = fps;
this.magnitude = magnitude;
///////////////////////////////////////////////////////////////////////////////////////////////////
double xPoint[][][] = new double[value][fps][64];
double yPoint[][][] = new double[value][fps][64];
for (int counter = 0; counter < value; counter++) {
for (int i = 0; i < fps; i++) {
for (int j = 0; j < (44100 / fps); j += ((44100 / fps) / 64)) {
xPoint[counter][i][j] = magnitude[counter][i][j];
for (int t = 0; t < ((44100 / fps) / 65); t++) { //64 is the number of bands taken into and only 55 from them are used
if(j+t < magnitude[0][0].length) {
xPoint[counter][i][j] += magnitude[counter][i][j + t];
}
System.out.println("Here xPoint[" +i+"]["+j+"]" + (j + t));
}
xPoint[counter][i][j] /= (int) ((44100 / fps) / 64);
}
int t = 0;
for (double angle = addingAngle; angle < 2 * Math.PI + addingAngle; angle += 2 * Math.PI / 55) {
xPoint[counter][i][t] *= Math.cos(angle); //All X points [second][frame][band]
yPoint[counter][i][t] *= Math.sin(angle); //All Y points [second][frame][band]
t++;
}
addingAngle += Math.PI / 110; //110 = 55 points * 2 so rotation is slower
}
this.xPoint = xPoint;
this.yPoint = yPoint;
// Up to here we have 64 xPoints and 64 yPoints, but only the first 55 of each are multiplied by the angle
// jl.setIcon(new ImageIcon("/images/T.png"));
}
for (int i = 0; i < 55; i++) {
System.out.println("Point[" + i + "] is: " + xPoint[0][0][i]);
}
///////////////////////////////////////////////////////////////////////////////////////////////////
JFrame window = new JFrame();
window.add(new DrawingFunction());
window.pack();
window.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
window.setLocationRelativeTo(null);
window.setSize(frameWidth, frameHeigth);
window.setBackground(Color.blue);
window.setVisible(true);
repaint();
}
@Override
protected void paintComponent(Graphics g) {
g.setColor(Color.black);
g.fillRect(800, 500, 300, 300); //g.translate(frameWidth/2, frameHeigth/2);
Polygon p = new Polygon();
for (int i = 0; i < 55; i++)
p.addPoint(15 * (int) xPoint[0][0][i], 15 * (int) yPoint[0][0][i]);
g.setColor(Color.black);
g.drawPolygon(p);
g.fillRect(800, 800, 400, 400);
validate(); // So image appears even if screen is small
我知道代码很长，希望它不难阅读，这是我第一次在这里提出问题
答案 0 :(得分：2)
我会在这里查看以下几行：
double xPoint[][][] = new double[value][fps][64];
//...
for (int j = 0; j < (44100 / fps); j += ((44100 / fps) / 64)) {
xPoint[counter][i][j] = magnitude[counter][i][j];
请注意，输入的fps为30，因此（（44100/30）/ 64））= 22.96875（或22为int）。所以当这个循环迭代时，j将如下：
j = 0
j = 22
j = 44
j = 66（数组越界）
答案 1 :(得分：1)
fps的值是30（如果我没有遗漏任何东西）。 44100 / fps = 1,470。所以，j从0到1,469。但是，你的数组的第三个维度只有64 ......
double xPoint[][][] = new double[value][fps][64];
double yPoint[][][] = new double[value][fps][64];
for (int counter = 0; counter < value; counter++) {
for (int i = 0; i < fps; i++) {
for (int j = 0; j < (44100 / fps); j += ((44100 / fps) / 64)) {
xPoint[counter][i][j] = magnitude[counter][i][j];