标题: indexOf源码问题 [打印本页] 作者: NOTHIING 时间: 2016-9-19 15:40 标题: indexOf源码问题 static int indexOf(char[] source, int sourceOffset, int sourceCount,
char[] target, int targetOffset, int targetCount,
int fromIndex) {
if (fromIndex >= sourceCount) {
return (targetCount == 0 ? sourceCount : -1);
}
if (fromIndex < 0) {
fromIndex = 0;
}
if (targetCount == 0) {
return fromIndex;
}
char first = target[targetOffset];
int max = sourceOffset + (sourceCount - targetCount); //如果targetCount大于sourceOffset,max岂不是会越界
for (int i = sourceOffset + fromIndex; i <= max; i++) {
/* Look for first character. */
if (source != first) {
while (++i <= max && source != first);
}
/* Found first character, now look at the rest of v2 */
if (i <= max) {
int j = i + 1;
int end = j + targetCount - 1;
for (int k = targetOffset + 1; j < end && source[j]
== target[k]; j++, k++);
if (j == end) {
/* Found whole string. */
return i - sourceOffset; //为什么要减 sourceOffset
}
}
}
return -1;
}