java.lang.ArrayIndexOutOfBoundsException: 3 错误
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java.lang.ArrayIndexOutOfBoundsException: 3 error
提问by chlc
I have the following piece of code for which i am getting java.lang.ArrayIndexOutOfBoundsException
我有以下一段代码 java.lang.ArrayIndexOutOfBoundsException
//divides ACode by 10 as many times as specified by the DecimalDigitPosition
public static int getDecimalDigit(int ACode, int decimalDigitPosition) {
if (decimalDigitPosition == 0)
return ACode;
else {
ACode = ACode / (10 * decimalDigitPosition);
int remainder = ACode % 10;
return remainder;
}
}
I am suspecting this line...
我怀疑这条线...
digit[i] = getDecimalDigit(samples[i].getValue(), 0);
in the code below which could be the reason for this exception.
在下面的代码中，这可能是此异常的原因。
//start a method to decode the message.
public static void decodeMessage(String filename) {
Sound s = new Sound(filename);
SoundSample[] samples = s.getSamples();
int[] digit = new int[3];
String message = "";
int sampleIndex = 0;
boolean nullReached = false;
while (!nullReached) {
int asciiValue = 0;
for (int i = sampleIndex; i < sampleIndex + 3; i++) {
if (i < samples.length) {
// this line could be the cause of error..
digit[i] = getDecimalDigit(samples[i].getValue(), 0);
asciiValue += digit[i - sampleIndex] * (((i - sampleIndex) == 0)
? 1
: ((i - sampleIndex) * 10));
} else {
for (int j = 0; j < 3; j++) {
digit[j] = 0;
}
break;
}
}
if (digit[0] == digit[1]
&& digit[1] == digit[2]
&& digit[2] == 0)
nullReached = true;
message += (char) asciiValue;
}
}
Stack trace:
堆栈跟踪：
java.lang.ArrayIndexOutOfBoundsException: 3 at project.decodeMessage(project.java:107) at project.main(project.java:33) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.jav??a:25) at java.lang.reflect.Method.invoke(Method.java:597) at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:27??2) >
java.lang.ArrayIndexOutOfBoundsException: 3 at project.decodeMessage(project.java:107) at project.main(project.java:33) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke( NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.jav??a:25) at java.lang.reflect.Method.invoke(Method.java:597) at edu.rice.cs.drjava。 model.compiler.JavacCompiler.runCommand(JavacCompiler.java:27??2) >
采纳答案by Mike B
The problem is likely here in your decodeMessagemethod. I've snipped out some code to isolate the problem:
问题可能出在您的decodeMessage方法中。我剪掉了一些代码来隔离问题：
int[] digit = new int[3];
while (!nullReached)
{
for (int i = sampleIndex; i < sampleIndex + 3; i++)
{
if (i < samples.length)
{
digit[i] = getDecimalDigit(samples[i].getValue(), 0); // This should be the line that throws the exception
}
}
sampleIndex += 3;
}
The second time through your whileloop, sampleIndexwill be 3, so iwill start at 3. Then you try to dereference digit[i], which would be digit[3]. Since digit[]is an int[3], then digit[3]is out of the bounds of the array.
第二次通过您的while循环，sampleIndex将是3，因此i将从 开始3。然后您尝试取消引用digit[i]，这将是digit[3]. 由于digit[]是 an int[3]，则digit[3]超出了数组的范围。
Maybe you want to do this instead:
也许你想这样做：
digit[i-sampleIndex] = getDecimalDigit(samples[i].getValue(), 0);
