IRC login missing return statement

Question

I need to do IRC client and I have a problem with login. I am trying to loop through server input to find the massage 004 or 433 which states for success login or for login in use. This is my code: `

import ecs100.*;
import java.io.*;
import java.net.Socket; 
import java.util.*; 



public class ChatClient {
private String server = "irc.ecs.vuw.ac.nz";  
private static final int IRC_PORT = 6667;     



private static String nick; 
private static String name;
private Socket socket;
private Scanner serverIn;
private PrintStream serverOut; 
private String line; 
private String channel; 
// Constructor
public ChatClient (){
    this.setupGUI();

}

public void setupGUI(){ 
    UI.addButton("Connect", this::connect);


}



public void connect(){

    try {

    socket = new Socket(server,IRC_PORT); 
    serverIn = new Scanner(socket.getInputStream());
    serverOut = new PrintStream(socket.getOutputStream());
    UI.println("login");
    this.login();
    UI.println("listening");
    this.listenToServer(); 
}catch(IOException e){UI.println("IO failure "+ e);}

}

private boolean login(){
    String username = UI.askToken("Enter your usercode: ");
    String realname = UI.askString("Enter your real name: ");

    this.nick = username;
    this.name = realname;
    send("NICK " + username);
    send("USER " + username + " 0 unused :" + realname);
    UI.println("listening to server");
   while(this.serverIn.hasNext()){
    this.line = serverIn.nextLine();
    UI.println("SERVER" + line);
    if (line.indexOf("004") >= 0){
        UI.println("true");
        return true;
    } else if(line.indexOf("433") >= 0){
        UI.println("failed to connect, username already in use");
        return false;
    } else {
        UI.println("else");
        return false;
    }
}

}

private void send(String msg){

      serverOut.print(msg + "\r\n");

    serverOut.flush();

}


private void listenToServer() {

    while(this.serverIn.hasNext()){
        String line = serverIn.nextLine();
        UI.println("SERVER" + line);
        if(line.equals("SQUIT")){
            this.closeConnection();
        }
        if(line.equals("PING")){
          String pingMsg = line.split(" ",2)[1];  
          this.send("PONG " + pingMsg);  
        }
    }
}


public void closeConnection(){

    try {
    this.socket.close();
    this.serverIn.close();
    this.serverOut.close();
    UI.println("Closed");
} catch(IOException e){UI.println("IO failure "+ e);}
}

public void joinChannel(){
    String channel = UI.askString("Enter channel name: ");
    send("JOIN " + channel);
}
public void leaveChannel(){
    send("PART " + channel);
}

public static void main(String[] args) {
    new ChatClient();
}

}

The problem is that it keeps trowing missing return statement in login method. Can anyone please look and my code and see what might be wrong here ?

EDIT: ok so when i change the if statement to two if's and put return false outside of the loop, program works. Can someone explain why the if/else statement inside of the while loop is not working ?

  private boolean login(){
    String username = UI.askToken("Enter your usercode: ");
    String realname = UI.askString("Enter your real name: ");
    this.nick = username;
    this.name = realname;
    send("NICK " + username);
    send("USER " + username + " 0 unused :" + realname);
    UI.println("listening to server");
   while(this.serverIn.hasNext()){
    this.line = serverIn.nextLine();
    UI.println("SERVER" + line);
    if (line.indexOf("004") >= 0){
        UI.println("true");
        return true;
    } 
    if(line.indexOf("433") >= 0){
        UI.println("failed to connect, username already in use");
        return false;
    } 
   }
   UI.println("else");
   return false;
}
enter code here

score 0 · Accepted Answer · answered May 16 '18 at 11:15

Because there's a code path that would result in no return being called, and the compiler can't allow that for a non-void method.

If this.serverIn.hasNext() returns false, what would the method return if you don't have a return statement at the end? It needs to return a boolean after all.

The program logic may be written so that the particular code path is never taken, but it's theoretically possible and that's why the compiler complains.

IRC login missing return statement

1 Answers1