Parse string with java 8 streams

Question

I have ip address string like "192.168.1.1". Is it possible to parse string using java 8 streams and get primitive byte array as a result. Currently i have code

Arrays.stream(address.split("\\."))
 .map(UnsignedBytes::parseUnsignedByte)
 .toArray(Byte[]::new);

where is UnsignedBytes is guava class which return byte, but this code return Byte[] not byte[]

Update: Yes, i read about why ByteStream class is absent. My question is about, is it possible to get byte array using java-8 streams, without overhead such as create intermediate list.

• Louis Wasserman: The only way I could possibly conceive of doing that would be to write a custom collector. That could work, but it might be tricky.
• Hank D: You might collect to a list and use guava's Bytes.toArray to get a primitive array.
• user140547: Possible duplicate of In Java 8, is there a ByteStream class?
• Hank D: see the final collect in this answer: stackoverflow.com/a/36613808/3487617
• JB Nizet: Frankly, this is an interesting intellectual effort, but this is the kind of situation where a plain old simple for loop is much simpler and readable. And you won't parallelize that stream, so it doesn't even have that advantage.

Answer 1

You could just use Java's InetAddress class.

 InetAddress i = InetAddress.getByName("192.168.1.1");
 byte[] bytes = i.getAddress();

• Bohemian: I like this answer, but the javadoc says The result is in network byte order: the highest order byte of the address is in getAddress()[0]. I think you need to reverse the byte array to suit OP's need.
• Robert: @Bohemian Not sure what order the OP wants. The code above has 192 in bytes[0], 168 in bytes[1], and so on. Which makes sense to me.
• Bohemian: I must have been thinking bits (where 0 is the "last" bit). This is fine!

Answer 2

You can use Pattern.splitAsStream(CharSequence) use a ByteArrayOutputStream in a collector:

byte[] bytes = Pattern.compile("\\.")
 .splitAsStream(address)
 .mapToInt(Integer::parseInt)
 .collect(
 ByteArrayOutputStream::new,
 ByteArrayOutputStream::write,
 (baos1, baos2) -> baos1.write(baos2.toByteArray(), 0, baos2.size())
 )
 .toByteArray();

Collect code adapted from https://stackoverflow.com/a/32470838/3255152.

• lscoughlin: I like this answer better because it fits in the theme of the question, and would be useful outside of just parsing IP addresses.