Question

I am trying to open up a TCP socket in my client application so that it can talk to my server.
after going through the documentation, i am curious about the socket constructor, which takes two parameters.

Socket(InetAddress dstAddress, int dstPort)
Creates a new streaming socket connected to the target host specified by the parameters dstAddress and dstPort.

and its description is as above. So as I learned, after creating the socket, I should have explicitly called the connect function in order for it to connect to the server. But in some TCP client sample codes I found online, none of them actually calls the connect function

connect(SocketAddress remoteAddr, int timeout)

So I am thinking if the constructor automatically connects to the server after being created? the three-ways handshake is done. or I have to explicitly call the connect function after the constructor? Thank you so much

Answer 1

Only the two constructors that don’t take any kind of target do not connect:

• Socket()
  Creates a new unconnected socket.

• Socket(Proxy)
  Creates a new unconnected socket using the given proxy type.

All the other constructors where you pass the target as hostname or address do connect:

• Socket(String, int)
  Creates a new streaming socket connected to the target host specified by the parameters dstName and dstPort.

• Socket(String, int, InetAddress, int) Creates a new streaming socket connected to the target host specified by the parameters dstName and dstPort.

• Socket(InetAddress, int)
  Creates a new streaming socket connected to the target host specified by the parameters dstAddress and dstPort.

• Socket(InetAddress, int, InetAddress, int)
  Creates a new streaming socket connected to the target host specified by the parameters dstAddress and dstPort.

I left out the two deprecated constructors.

This is straight from the Android API documentation for java.lang.Socket.