如何编码 Stream.findNth()?
类似于Stream.findFirst()
,有没有办法写Stream.findNth()
?
Similar to Stream.findFirst()
, is there a way to write Stream.findNth()
?
我正在通过重写一些遗留代码来练习 Java 8.而且,我想知道如何使用 Stream API 编写以下函数.
I'm practicing Java 8 by rewriting some legacy code. And, I'm wondering how the below function can be written using Stream API.
static curPipeNumber = 0;
/** skipToEntry() updates 'curPipeNumber' to 'pipeNumber' and returns the first byte position of the word before the ('pipeNumber')-th pipe.
* It does so by reading and ignoring unnecessary bytes from the buffer.
* e.g.,
*/
static int skipToEntry(byte[] buf, int len, int nextByteToBeRead, int pipeNumber) {
if(curPipeNumber == pipeNumber)
return nextByteToBeRead;
for(; nextByteToBeRead < len; nextByteToBeRead++) {
if(buf[nextByteToBeRead] == '|') {
++curPipeNumber;
if(curPipeNumber == pipeNumber) {
return ++nextByteToBeRead;
}
}
}
return nextByteToBeRead;
}
我希望它会转化为:
static int skipToEntry(byte[] buf, int len, int nextByteToBeRead, int pipeNumber) {
if(curPipeNumber == pipeNumber)
return nextByteToBeRead;
OptionalInt pipeIndex = IntStream.range(i, len)
.filter(n -> buf[n] == '|')
.findNth(pipeNumber);
curPipeNumber = pipeNumber;
nextByteToBeRead = pipeIndex.getAsInt() + 1;
return nextByteToBeRead;
}
推荐答案
OptionalInt result = stream.skip(n-1).findFirst();
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