how to get the next ip address from a given ip in java?

Folks,

Am looking for a Java code snippet, which gives the next address from the given IP.

so getNext开发者_如何转开发IPV4Address("10.1.1.1") returns "10.1.1.2".

String crunching can be done but might end up messy. Is there a much formalized way for doing this.

Thanks for your time.

Am looking for a Java code snippet, which gives the next address from the given IP.

Here's a snippet for you:

public static String getNextIPV4Address(String ip) {
    String[] nums = ip.split("\\.");
    int i = (Integer.parseInt(nums[0]) << 24 | Integer.parseInt(nums[2]) << 8
          |  Integer.parseInt(nums[1]) << 16 | Integer.parseInt(nums[3])) + 1;

    // If you wish to skip over .255 addresses.
    if ((byte) i == -1) i++;

    return String.format("%d.%d.%d.%d", i >>> 24 & 0xFF, i >> 16 & 0xFF,
                                        i >>   8 & 0xFF, i >>  0 & 0xFF);
}

Examples input / output (ideone.com demonstration):

10.1.1.0        -> 10.1.1.1
10.255.255.255  -> 11.0.0.0
10.0.255.254    -> 10.1.0.0

This will get you started (add error handling, corner cases etc.):

public static final String nextIpAddress(final String input) {
    final String[] tokens = input.split("\\.");
    if (tokens.length != 4)
        throw new IllegalArgumentException();
    for (int i = tokens.length - 1; i >= 0; i--) {
        final int item = Integer.parseInt(tokens[i]);
        if (item < 255) {
            tokens[i] = String.valueOf(item + 1);
            for (int j = i + 1; j < 4; j++) {
                tokens[j] = "0";
            }
            break;
        }
    }
    return new StringBuilder()
    .append(tokens[0]).append('.')
    .append(tokens[1]).append('.')
    .append(tokens[2]).append('.')
    .append(tokens[3])
    .toString();
}

Test case:

@Test
public void testNextIpAddress() {
    assertEquals("1.2.3.5", nextIpAddress("1.2.3.4"));
    assertEquals("1.2.4.0", nextIpAddress("1.2.3.255"));
}

IP addresses aren't "sequential", so I doubt you'll find a library to do it for you.

An IP address is pretty much just a 32-bit integer. Depending on how you are storing it, it may be possible to simply increment this underlying value. This probably won't be very reliable however as you have to consider subnets, different address classes etc.

As dty points out, IP addresses aren't sequential, so I wouldn't imagine there is any kind of 'formal' way of doing this.

Split by ., cast last element to int and increment it. Check whether its value is less than 254 or you will win yourself a broadcast address. Pray that you're always dealing with full class C subnets.

Split the string by "." and convert the 4 strings to bytes. Multiply all the bytes to get int multiplication. Increase the result. Restore bytes by dividing the integer and storing mod in each byte. Convert the bytes to strings and concat all the strings.

If using 3rd party libraries is OK, Guava can be used to get the next (or any number after an) IP address like this:

InetAddress a = InetAddresses.forString("192.168.1.1");
int i = InetAddresses.coerceToInteger(a);
InetAddress b = InetAddresses.fromInteger(i+1);
String s = InetAddresses.toAddrString(b);
System.out.println(s);