Java Socket Class

The Socket class acts as an endpoint for communication between two machines. It implements client sockets.

Methods

Method	Description
bind(SocketAddress bindpoint)	This method binds the given socket to the specified local address.
close()	This method closes the socket.
connect(SocketAddress endpoint) connect(SocketAddress endpoint, int timeout)	The connect() method connects this socket to the server. This method connects this socket to the server with a specified timeout value.
getChannel()	It returns a unique SocketChannel object associated with this socket.
getInetAddress()	It returns the address to which the socket is connected.
getInputStream()	It returns an input stream for the specified socket.
getKeepAlive()	This method tests if the SO_KEEPALIVE option is enabled or not.
getLocalAddress()	It returns the local address to which the given socket is bound.
getLocalPort()	It gets the local port number to which the specified socket is bound.
getLocalSocketAddress()	This method gets the address of the endpoint to which this socket is bound.
getOOBInline()	This method tests whether the SO_OOBINLINE option is enabled or not.
getOutputStream()	This method returns an output stream for the specified socket.
getPort()	This method returns the remote port number to which the socket is connected.
getReceiveBufferSize()	It returns the value of the SO_RCVBUF option for this Socket.
getRemoteSocketAddress()	This method either returns the address of the endpoint to which this socket is connected or it returns null if the socket is unconnected.
getReuseAddress()	It tests whether the SO_REUSEADDR option is enabled or not.
getSendBufferSize()	This method gets the value of the SO_SNDBUF option for this Socket.
getSoLinger()	This method returns setting for the SO_LINGER option.
getSoTimeout()	It returns the setting for the SO_TIMEOUT option if it is enabled, else it returns 0 if the option is disabled.
getTcpNoDelay()	This method tests whether the TCP_NODELAY option is enabled or not.
getTrafficClass()	This method returns the traffic class or type-of-service in the IP header for packets sent from this Socket
isBound()	It returns the binding state for this socket.
isClosed()	This method returns the closed state of this socket.
isConnected()	This method returns the connection state of the socket.
isInputShutdown()	It returns whether the read-half of the socket connection is closed or not.
isOutputShutdown()	It returns whether the write-half of the socket connection is closed or not.
sendUrgentData(int data)	This method sends one byte of urgent data on the socket.
setKeepAlive(boolean on)	This method enables or disables the SO_KEEPALIVE option for this socket.
setOOBInline(boolean on)	This method enables or disables the SO_OOBINLINE option for this socket.
setReceiveBufferSize(int size)	This method returns the SO_RCVBUF option to the specified value for this Socket.
setReuseAddress(boolean on)	This method enables or disables the SO_REUSEADDR socket option for this socket.
setSendBufferSize(int size)	This method returns the SO_SNDBUF option to the specified value for this Socket.
setSoLinger(boolean on, int linger)	It enables or disables the SO_LINGER option with the specified linger time in seconds.
setSoTimeout(int timeout)	This method enables or disables the SO_TIMEOUT option with the specified time in milliseconds.
setTcpNoDelay(boolean on)	This method enables or disables the TCP_NODELAY option for this socket.
setTrafficClass(int tc)	It returns the traffic class or type-of-service octet in the IP header for packets sent from the Socket.
shutdownInput()	This method places the input stream for this socket at the end of this stream.
shutdownOutput()	This method disables the output stream for this socket.
toString()	This method converts this socket to a String.

Example 1

import java.io.IOException;
import java.net.*;
public class JavaSocketExample1  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //setSendBufferSize() sets the send buffer size or SO_SNDBUF option with the specified value
        socket.setSendBufferSize(67);
        //getSendBufferSize() method returns the buffer size(SO_SNDBUF) used by the platform for output
        System.out.println("Send Buffer size: "+socket.getSendBufferSize());
        //enabling the boolean value true
        boolean on=false;
        //setKeepAlive() method either enables or disables the SO_KEEPALIVE option
        socket.setKeepAlive(on);
        //getKeepAlive() returns  a boolean indicating whether SO_KEEPALIVE option is enabled or not
        if(socket.getKeepAlive()){
            System.out.println("SO_KEEPALIVE option is enabled");
        }
        else{
            System.out.println("SO_KEEPALIVE option is disabled");
        }
        //getRemoteSocketAddress() returns the address of the endpoint of the specified socket if the socket is connected
        System.out.println("Remote socket address: "+socket.getRemoteSocketAddress());
    }
 }

Test it Now

Output:

Send Buffer size: 67
SO_KEEPALIVE option is disabled
Remote socket address: localhost/127.0.0.1:1085

Example 2

import java.io.IOException;
import java.net.*;
public class JavaSocketExample2  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //enabling the SO_LINGER option
        boolean on=true;
        //setting the integer value for timeout
        int timeout=90;
        socket.setSoLinger(on,timeout);
        //getSoLinger() method returns the setting if the SO_Linger option is set
        System.out.println("Send Buffer size: "+socket.getSoLinger());
        //integer timeout value
        socket.setSoTimeout(timeout);
        //getSoTimeout() method returns the setting for SO_TIMEOUT option
        System.out.println("Timeout value: "+socket.getSoTimeout());
        //setTcpNoDelay() method enables or disables the SO_TIMEOUT option
        socket.setTcpNoDelay(on);
        //getTcpNoDelay() returns the setting for SO_TIMEOUT option
        System.out.println("SO_TIMEOUT option is enabled: "+socket.getTcpNoDelay());
        //setKeepAlive() method either enables or disables the SO_KEEPALIVE option
        socket.setKeepAlive(on);
        //getKeepAlive() returns  a boolean indicating whether SO_KEEPALIVE option is enabled or not
        System.out.println("SO_KEEPALIVE is enabled: "+socket.getKeepAlive());
        //getLocalSocketAddress() returns the address of the endpoint to which this socket is bound
        System.out.println("Local socket address: "+socket.getLocalSocketAddress());
    }
 }

Test it Now

Output:

Send Buffer size: 90
Timeout value: 90
SO_TIMEOUT option is enabled: true
SO_KEEPALIVE is enabled: true
Local socket address: /127.0.0.1:1085

Example 3

import java.io.IOException;
import java.net.*;
public class JavaSocketExample3  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //The getInetAddress() returns the Inet Address for this socket
        System.out.println("Inet address: "+socket.getInetAddress());
        //setting the buffer size with the help of setReceiveBufferSize() method
        socket.setReceiveBufferSize(10);
        //getReceiveBufferSize() method returns the buffer size for this socket
        System.out.println("Buffer size: "+socket.getReceiveBufferSize());
        //setReuseAddress() method enables or disables the SO_REUSEADDR option
        socket.setReuseAddress(true);
        //getReuseAddress() method returns boolean value 'true' if SO_REUSEADDR option is enabled else it return false
        System.out.println("SO_REUSEADDR option is enabled: "+socket.getReuseAddress());
        //closing the socket will have no effect it will continue to return the same binding state
        socket.close();
        //isClosed() method returns whether the socket is closed or not
        System.out.println("The socket is closed: "+socket.isClosed());
        //The toString() method returns the string representation for the given socket.
        socket.toString();
        //it will return the connecting port and binding address
        System.out.println(socket);
    }
 }

Test it Now

Output:

Inet address: localhost/127.0.0.1
Buffer size: 10
SO_REUSEADDR option is enabled: true
The socket is closed: true
Socket[addr=localhost/127.0.0.1,port=1085,localport=1085]

Example 4

import java.io.DataOutputStream;
import java.io.IOException;
import java.net.*;
public class JavaSocketExample4  {
    public static void main(String[] args) throws IOException {
        Socket socket = new Socket();
        InetAddress inetAddress=InetAddress.getByName("localhost");
        //the port should be greater or equal to 0, else it will throw an error
        int port=1085;
        //calling the constructor of the SocketAddress class
        SocketAddress socketAddress=new InetSocketAddress(inetAddress, port);
        //binding the  socket with the inetAddress and port number
        socket.bind(socketAddress);
        //connect() method connects the specified socket to the server
        socket.connect(socketAddress);
        //The isConnected() method returns the connected state for this socket
        System.out.println("The socket is connected: "+socket.isConnected());
        //The isBound() states whether this socket is bounded or not
        System.out.println("The socket is binded: "+socket.isBound());
        //The getLocalPort() method returns the port number for this socket.
        System.out.println("Local Port: "+socket.getLocalPort());
        //getOutputStream() returns an output stream for writing bytes to this socket.
        DataOutputStream  outputStream=new DataOutputStream(socket.getOutputStream());
        System.out.println("Output Stream: "+outputStream);
    }
 }

Test it Now

Output:

The socket is connected: true
The socket is binded: true
Local Port: 1085
Output Stream: java.io.DataOutputStream@1540e19d

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