find and fix the error

import java.io.*;

import java.net.*;

class TCPclient {

public static void main(String argv[]) throws Exception

{

String sentence;

String modifiedSentence;

BufferedReader inFromUser =

new BufferedReader(new InputStreamReader(System.in));

Socket clientSocket = new Socket("Localhost", 6789);

DataOutputStream outToServer =

new DataOutputStream(clientSocket.getOutputStream());

BufferedReader inFromServer =

new BufferedReader(new

InputStreamReader(clientSocket.getInputStream()));

sentence = inFromUser.readLine();

outToServer.writeBytes(sentence + ' ');

modifiedSentence = inFromServer.readLine();

System.out.println("FROM SERVER: " + modifiedSentence);

clientSocket.close();

}

}

import java.io.BufferedReader;

import java.io.DataOutputStream;

import java.io.InputStreamReader;

import java.net.ServerSocket;

import java.net.Socket;

class TCPserver {

public static void main(String argv[]) throws Exception

{

String clientSentence;

String newSentence="";

ServerSocket welcomeSocket = new ServerSocket(6789);

while(true) {

Socket connectionSocket = welcomeSocket.accept();

BufferedReader inFromClient =

new BufferedReader(new

InputStreamReader(connectionSocket.getInputStream()));

DataOutputStream outToClient =

new DataOutputStream(connectionSocket.getOutputStream());

clientSentence = inFromClient.readLine();

//here we modify the sentence

//we first need to define and initialize a boolean to check wether a letter is the first letter in a word

boolean spaceAhead = true ; // to capitalize first letter in the sentence immedietly without checking for a space ahead

//we will loop through the sentence

for (int i = 0; i

//when found a letter

if(Character.isLetter(clientSentence.charAt(i))){

//if it the first letter in a word

if(spaceAhead){

char modified = Character.toUpperCase(clientSentence.charAt(i));

newSentence+=modified;

spaceAhead = false;

}

//if it was just a part of a word (not first letter)

else{

char notmodified = Character.toUpperCase(clientSentence.charAt(i));

newSentence+=notmodified;

spaceAhead = false;

}}

//if it was not a letter (it must be a space) then change isSpace to true

char space = Character.toUpperCase(clientSentence.charAt(i));

newSentence+=space;

spaceAhead = true;

}

outToClient.writeBytes(newSentence);

}

}

}