我目前正在编写一个程序，将BufferedImage转换为音乐。当我得到BufferedImage的宽度和高度时，值是正确的。但是，在我用于获取像素的FOR循环内部，我正在操纵其中一个FOR循环值（i++）。在void的末尾，我将值重置为原始状态（i--）。该程序不会评估整个图像，而是给我这个错误：
java.lang.ArrayIndexOutOfBoundsException: Coordinate out of bounds!
我该如何解决此错误？这是我的代码：
try {
String fp = jTextField1.getText();
File pict = new File(fp);
BufferedImage img = ImageIO.read(pict);
// int keybase = img.getRGB(1, 1);
// int red = (keybase & 0x00ff0000) >> 16;
// int green = (keybase & 0x0000ff00) >> 8;
// int blue = keybase & 0x000000ff;
int width = img.getWidth();
int height = img.getHeight();
String key = null;
int keybase = img.getRGB(1, 1);
int keyred = (keybase & 0x00ff0000) >> 16;
int keygreen = (keybase & 0x0000ff00) >> 8;
int keyblue = keybase & 0x000000ff;
int keyAvg = (keyred + keygreen + keyblue) / 3;
if (keyAvg <= 10) {
key = "Cmaj";
}
else if (keyAvg <=20 && keyAvg > 10) {
key = "Cmin";
}
else if (keyAvg <=30 && keyAvg > 20) {
key = "C#maj";
}
else if (keyAvg <=40 && keyAvg > 30) {
key = "C#min";
}
else if (keyAvg <=50 && keyAvg > 40) {
key = "Dmaj";
}
else if (keyAvg <=60 && keyAvg > 50) {
key = "Dmin";
}
else if (keyAvg <=70 && keyAvg > 60) {
key = "D#maj";
}
else if (keyAvg <=80 && keyAvg > 70) {
key = "D#min";
}
else if (keyAvg <=90 && keyAvg > 80) {
key = "Emaj";
}
else if (keyAvg <=100 && keyAvg > 90) {
key = "Emin";
}
else if (keyAvg <=110 && keyAvg > 100) {
key = "Fmaj";
}
else if (keyAvg <=120 && keyAvg > 110) {
key = "Fmin";
}
else if (keyAvg <=130 && keyAvg > 120) {
key = "F#maj";
}
else if (keyAvg <=140 && keyAvg > 130) {
key = "F#min";
}
else if (keyAvg <=150 && keyAvg > 140) {
key = "Gmaj";
}
else if (keyAvg <=160 && keyAvg > 150) {
key = "Gmin";
}
else if (keyAvg <=170 && keyAvg > 160) {
key = "G#maj";
}
else if (keyAvg <=180 && keyAvg > 170) {
key = "G#min";
}
else if (keyAvg <=190 && keyAvg > 180) {
key = "Amaj";
}
else if (keyAvg <=200 && keyAvg > 190) {
key = "Amin";
}
else if (keyAvg <=210 && keyAvg > 200) {
key = "A#maj";
}
else if (keyAvg <=220 && keyAvg > 210) {
key = "A#min";
}
else if (keyAvg <=230 && keyAvg > 220) {
key = "Bmaj";
}
else {
key = "Bmin";
}
int tempoVal = 0;
int tempobase = img.getRGB(2, 2);
int tempored = (tempobase & 0x00ff0000) >> 16;
int tempogreen = (tempobase & 0x0000ff00) >> 8;
int tempoblue = tempobase & 0x000000ff;
if (tempored > tempogreen && tempored > tempoblue) {
tempoVal = tempored;
}
else if (tempogreen > tempored && tempogreen > tempoblue) {
tempoVal = tempogreen;
}
else if (tempoblue > tempored && tempoblue > tempogreen) {
tempoVal = tempoblue;
}
else {
tempoVal = 120;
}
String tempo = "T" + String.valueOf(tempoVal) + " ";
String inst;
int instbase = img.getRGB(3, 3);
int red5 = (instbase & 0x00ff0000) >> 16;
int green5 = (instbase & 0x0000ff00) >> 8;
int blue5 = instbase & 0x000000ff;
int instAvg = (red5 + green5 + blue5) / 3;
if (instAvg > 111) {
instAvg = instAvg / 2;
inst = "I" + String.valueOf(instAvg) + " ";
}
else {
inst = "I" + String.valueOf(instAvg) + " ";
}
for (int i = 0; i < width; i++) {
for (int j = 0; j < height; j++) {
int note = img.getRGB(i, j);
int red = (note & 0x00ff0000) >> 16;
int green = (note & 0x0000ff00) >> 8;
int blue = note & 0x000000ff;
int noteAvg = (red + green + blue) / 3;
if (noteAvg >= 127) {
noteAvg = noteAvg / 2;
}
String nAvg = String.valueOf(noteAvg);
i++;
int len = img.getRGB(i, j);
int red2 = (len & 0x00ff0000) >> 16;
int green2 = (len & 0x0000ff00) >> 8;
int blue2 = len & 0x000000ff;
int noteAvg2 = (red2 + green2 + blue2) / 3;
String noteLen;
String keyVar = null;
if (noteAvg2 <= 42) {
noteLen = "W";
}
else if (noteAvg2 <= (42 * 2) && noteAvg2 > 42) {
noteLen = "H";
}
else if (noteAvg2 <= (42 * 3) && noteAvg2 > (42 * 2)) {
noteLen = "Q";
}
else if (noteAvg2 <= (42 * 4) && noteAvg2 > (42 * 3)) {
noteLen = "I";
}
else if (noteAvg2 <= (42 * 5) && noteAvg2 > (42 * 4)) {
noteLen = "S";
}
else {
noteLen = "T";
}
i++;
int keyvarbase = img.getRGB(i, j);
int red4 = (keyvarbase & 0x00ff0000) >> 16;
int green4 = (keyvarbase & 0x0000ff00) >> 8;
int blue4 = keyvarbase & 0x000000ff;
int noteAvg4 = (red4 + green4 + blue4) / 3;
int findKeyVar = noteAvg4 % 4;
if (findKeyVar == 1) {
keyVar = "min";
}
else if (findKeyVar == 2) {
keyVar = "maj";
}
else if (findKeyVar == 3) {
keyVar = "aug";
}
else {
keyVar = "dim";
}
i++;
int inv = img.getRGB(i, j);
int red3 = (inv & 0x00ff0000) >> 16;
int green3 = (inv & 0x0000ff00) >> 8;
int blue3 = inv & 0x000000ff;
int noteAvg3 = (red3 + green3 + blue3) / 3;
String inversion = null;
if (noteAvg3 <= (85 * 2) && noteAvg3 > 85) {
inversion = "^";
}
else if (noteAvg3 <= (85 * 3) && noteAvg3 > (85 * 2)) {
inversion = "^^";
}
if (noteAvg == 0) {
}
else {
String forPlayer = tempo + inst + "K" + key + " [" + nAvg + "]" + keyVar + noteLen;
midi.add(forPlayer);
midi.add("_");
player.play(forPlayer);
}
i--;
i--;
i--;
}
}
} catch (IOException ex) {
Logger.getLogger(I2MC.class.getName()).log(Level.SEVERE, null, ex);
}
我正在使用JFugue API。
答案 0 :(得分：2)
无论
for (int i = 0; i < width - 3; i++) { // Will use index i+3
或if s。
当您在循环中执行i++三次并使用i作为索引，然后使用三次i--时，
在单个循环步骤开始时，i + 3必须小于width才能成为有效索引。
虽然你的风格很细致，但使用
final int i1 = i + 1;
final int i2 = i + 2;
final int i3 = i + 3;
可能会使代码更具可读性。
i++的算法证明会更复杂，看起来像：
// Define VALID_I(index) = (0 <= index < width)
for (int i = 0; i < width - 3; i++) { // Will use index i+3
// Step pre-condition: 0 <= i < width - 3} => VALID_I(i)
... getRGG(i, j);
i++;
// 1 <= i < width - 2 => VALID_I(i)
i++;
// 1 <= 2 < width - 1 => VALID_I(i)
i++;
// 1 <= 3 < width => VALID_I(i)
i -= 3;
// Step post-condition: 0 <= i < width - 3} => VALID_I(i)
// Loop-invariant: Step post-condition == step pre-codition
}
替代if：
for（int i = 0; i＆lt; width; i ++）{//将使用索引i + 3 //步骤前置条件：0＆lt; = i＆lt; width}＆lt; =＆gt; VALID_I（I） ... getRGG（i，j）; 我++; // 1＆lt; = i＆lt; width + 1 =＆gt; VALID_I（I） if（i + 1＆gt; = width） 打破; // 1＆lt; = i＆lt; width =＆gt; VALID_I（I） 我++; if（i + 1＆gt; = width） 打破; // 2＆lt; = i＆lt; width =＆gt; VALID_I（I） 我++; if（i + 1＆gt; = width） 打破; // 3＆lt; = i＆lt; width = e＆gt; VALID_I（I） 我 - = 3; // 0＆lt; = i＆lt; width - 3 =＆gt; VALID_I（I） //步骤后置条件：0＆lt; = i＆lt; width - 3} =＆gt; VALID_I（I） //循环不变：步骤后置条件==步骤预编码 }
替代嵌套ifs相同。
对于i＆gt; = width - 3，这三种替代方案具有不同的行为。