Module java.base
Package java.net

Class InetSocketAddress

java.lang.Object
java.net.SocketAddress
java.net.InetSocketAddress
All Implemented Interfaces:
Serializable

public class InetSocketAddress extends SocketAddress
This class implements an IP Socket Address (IP address + port number) It can also be a pair (hostname + port number), in which case an attempt will be made to resolve the hostname. If resolution fails then the address is said to be unresolved but can still be used on some circumstances like connecting through a proxy.

It provides an immutable object used by sockets for binding, connecting, or as returned values.

The wildcard is a special local IP address. It usually means "any" and can only be used for bind operations.

Since:
1.4
See Also:
Socket, ServerSocket, Serialized Form
  • Constructor Details

    • InetSocketAddress

      public InetSocketAddress(int port)
      Creates a socket address where the IP address is the wildcard address and the port number a specified value.

      A valid port value is between 0 and 65535. A port number of zero will let the system pick up an ephemeral port in a bind operation.

      Parameters:
      port - The port number
      Throws:
      IllegalArgumentException - if the port parameter is outside the specified range of valid port values.
    • InetSocketAddress

      public InetSocketAddress(InetAddress addr, int port)
      Creates a socket address from an IP address and a port number.

      A valid port value is between 0 and 65535. A port number of zero will let the system pick up an ephemeral port in a bind operation.

      A null address will assign the wildcard address.

      Parameters:
      addr - The IP address
      port - The port number
      Throws:
      IllegalArgumentException - if the port parameter is outside the specified range of valid port values.
    • InetSocketAddress

      public InetSocketAddress(String hostname, int port)
      Creates a socket address from a hostname and a port number.

      An attempt will be made to resolve the hostname into an InetAddress. If that attempt fails, the address will be flagged as unresolved.

      If there is a security manager, its checkConnect method is called with the host name as its argument to check the permission to resolve it. This could result in a SecurityException.

      A valid port value is between 0 and 65535. A port number of zero will let the system pick up an ephemeral port in a bind operation.

      Parameters:
      hostname - the Host name
      port - The port number
      Throws:
      IllegalArgumentException - if the port parameter is outside the range of valid port values, or if the hostname parameter is null.
      SecurityException - if a security manager is present and permission to resolve the host name is denied.
      See Also:
      isUnresolved()
  • Method Details

    • createUnresolved

      public static InetSocketAddress createUnresolved(String host, int port)
      Creates an unresolved socket address from a hostname and a port number.

      No attempt will be made to resolve the hostname into an InetAddress. The address will be flagged as unresolved.

      A valid port value is between 0 and 65535. A port number of zero will let the system pick up an ephemeral port in a bind operation.

      Parameters:
      host - the Host name
      port - The port number
      Returns:
      an InetSocketAddress representing the unresolved socket address
      Throws:
      IllegalArgumentException - if the port parameter is outside the range of valid port values, or if the hostname parameter is null.
      Since:
      1.5
      See Also:
      isUnresolved()
    • getPort

      public final int getPort()
      Gets the port number.
      Returns:
      the port number.
    • getAddress

      public final InetAddress getAddress()
      Gets the InetAddress.
      Returns:
      the InetAddress or null if it is unresolved.
    • getHostName

      public final String getHostName()
      Gets the hostname. Note: This method may trigger a name service reverse lookup if the address was created with a literal IP address.
      Returns:
      the hostname part of the address.
    • getHostString

      public final String getHostString()
      Returns the hostname, or the String form of the address if it doesn't have a hostname (it was created using a literal). This has the benefit of not attempting a reverse lookup.
      Returns:
      the hostname, or String representation of the address.
      Since:
      1.7
    • isUnresolved

      public final boolean isUnresolved()
      Checks whether the address has been resolved or not.
      Returns:
      true if the hostname couldn't be resolved into an InetAddress.
    • toString

      public String toString()
      Constructs a string representation of this InetSocketAddress. This string is constructed by calling InetAddress.toString() on the InetAddress and concatenating the port number (with a colon).

      If the address is an IPv6 address, the IPv6 literal is enclosed in square brackets, for example: "localhost/[0:0:0:0:0:0:0:1]:80". If the address is unresolved, <unresolved> is displayed in place of the address literal, for example "foo/<unresolved>:80".

      To retrieve a string representation of the hostname or the address, use getHostString(), rather than parsing the string returned by this toString() method.

      Overrides:
      toString in class Object
      Returns:
      a string representation of this object.
    • equals

      public final boolean equals(Object obj)
      Compares this object against the specified object. The result is true if and only if the argument is not null and it represents the same address as this object.

      Two instances of InetSocketAddress represent the same address if both the InetAddresses (or hostnames if it is unresolved) and port numbers are equal. If both addresses are unresolved, then the hostname and the port number are compared. Note: Hostnames are case insensitive. e.g. "FooBar" and "foobar" are considered equal.

      Overrides:
      equals in class Object
      Parameters:
      obj - the object to compare against.
      Returns:
      true if the objects are the same; false otherwise.
      See Also:
      InetAddress.equals(java.lang.Object)
    • hashCode

      public final int hashCode()
      Returns a hashcode for this socket address.
      Overrides:
      hashCode in class Object
      Returns:
      a hash code value for this socket address.
      See Also:
      Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)