Java - Socket setTcpNoDelay() Method

Description

The Java Socket setTcpNoDelay(boolean on) enables/disables TCP_NODELAY flag. Internally it enables/disables Nagle's algorithm.

Declaration

Following is the declaration for java.net.Socket.setTcpNoDelay(boolean on) method.

public void setTcpNoDelay(boolean on) throws SocketException

Parameters

on − true to enable TCP_NODELAY, false to disable.

Return Value

N/A

Exception

SocketException − if there is an error in the underlying protocol, such as a TCP error.

Example 1

The following example shows the usage of Java Socket setTcpNoDelay() method to set the status of TCP_NODELAY flag of socket instance. As first step, we've created a Socket instance using no argument constructor. Then in order to create a SocketAddress object, we've initialized an InetAddress instance of localhost address. Using InetSocketAddress object, we've created a SocketAddress object and then using bind() method, we bind the address to the socket. Now we've disabled the TCP_NODELAY flag using setTcpNoDelay() method. Once done, we're printing the TCP_NODELAY flag using getTcpNoDelay() method, local port and inetaddress as shown. In the end, we closed the socket using close() method.

package com.tutorialspoint;

import java.io.IOException;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketAddress;

public class SocketDemo {
   public static void main(String[] args) throws IOException {
      Socket socket = new Socket();  
      InetAddress inetAddress=InetAddress.getByName("localhost");  
      SocketAddress socketAddress=new InetSocketAddress(inetAddress, 6066);  
      socket.bind(socketAddress); 
      socket.setTcpNoDelay(false);  
      System.out.println("Is TCP_NODELAY: "+socket.getTcpNoDelay()); 
      System.out.println("Port number: "+socket.getLocalPort()); 
      System.out.println("Inet Address: "+socket.getInetAddress()); 
      socket.close();
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Is TCP_NODELAY: false
Port number: 6066
Inet Address: null

Example 2

The following example shows the usage of Java Socket setTcpNoDelay() method to set the status of TCP_NODELAY flag of socket instance. As first step, we've created a Socket instance using no argument constructor. Now, we're printing the TCP_NODELAY flag using getTcpNoDelay() method. Then we're setting the TCP_NODELAY flag as true using setTcpNoDelay() method and print the same. In the end, we closed the socket using close() method.

package com.tutorialspoint;

import java.io.IOException;
import java.net.Socket;

public class SocketDemo {
   public static void main(String[] args) throws IOException {
      Socket socket = new Socket();  

      System.out.println("Is TCP_NODELAY: "+socket.getTcpNoDelay());
      socket.setTcpNoDelay(true);  
      System.out.println("Is TCP_NODELAY: "+socket.getTcpNoDelay());
      socket.close();
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Is TCP_NODELAY: false
Is TCP_NODELAY: true

Example 3

The following example shows the usage of Java Socket setTcpNoDelay() method to set the status of TCP_NODELAY flag of socket instance, if socket is already closed. As first step, we've created a Socket instance using no argument constructor. Using socket.close(), we're closing the socket. Then we're setting the TCP_NODELAY flag as true using setTcpNoDelay() method to check if it throws exception or not. Now, we're printing the TCP_NODELAY flag using getTcpNoDelay() method. Then we're setting the TCP_NODELAY flag as true using setTcpNoDelay() method and print the same. In the end, we closed the socket using close() method. As socket is already closed, setTcpNoDelay() method call throws an exception as shown below −

package com.tutorialspoint;

import java.io.IOException;
import java.net.Socket;

public class SocketDemo {
   public static void main(String[] args) throws IOException {
      Socket socket = new Socket();  
      socket.close();	  
      socket.setTcpNoDelay(true);  
      System.out.println("Is TCP_NODELAY: "+socket.getTcpNoDelay());
      socket.setTcpNoDelay(true);  
      System.out.println("Is TCP_NODELAY: "+socket.getTcpNoDelay());
      socket.close();
   }
}

Output

Let us compile and run the above program, this will produce the following result −

Exception in thread "main" java.net.SocketException: Socket is closed
	at java.base/java.net.Socket.setTcpNoDelay(Socket.java:996)
	at com.tutorialspoint.SocketDemo.main(SocketDemo.java:10)