if is not working but else is working so well. How to fix this? [duplicate]

code for server

import java.io.BufferedReader;
//imports system
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.InetAddress;
import java.net.ServerSocket;
import java.net.Socket;

public class main {
    public static String login;
    public static String b = "bbinterjju";
    public static String h = "hobag";
    @SuppressWarnings("resource")
    public static void main(String[] args) {
        try {
            int socketPort = 3009;
            ServerSocket serverSocket = new ServerSocket(socketPort); // 소켓 만들기
            Socket socketUser = null; // 클라이언트 접속시 사용할 Socket
            System.out.println("socket : " + socketPort + "으로 서버가 열렸습니다");
            
                        // 소켓 서버가 종료될 때까지 반복
                        while(true) {

                            socketUser = serverSocket.accept(); 
                            
                            //client login ip address
                            System.out.println("Client logined ip : " + socketUser.getLocalAddress());

                            //catch client message&data
                            InputStream input = socketUser.getInputStream(); 
                            BufferedReader reader = new BufferedReader(new InputStreamReader(input));
                            
                            String login= reader.readLine();
                            
                            if (login == "bbinterjju") {
                                OutputStream out = socketUser.getOutputStream();
                                PrintWriter writer = new PrintWriter(out, true);
                                writer.println("V");
                                System.out.println("logining ID : " + login);
                                System.out.println(" 'V' login succeded in : " + socketUser.getLocalAddress());
                            }   else {
                                OutputStream out = socketUser.getOutputStream();
                                PrintWriter writer = new PrintWriter(out, true);
                                writer.println("X(ID_not_corret)");
                                System.out.println("logining ID : " + login);
                                System.out.println(" 'X' failled(No Id found) in : " + socketUser.getLocalAddress());
                                System.out.println("------------------------------------------------------------");
                            }
                            
                            
                           
                
                        }           
            
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

code for client login

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.net.Socket;

public class auth {
    public static GUI G = new GUI();
    public static yellowstrawberry_client yst_c = new yellowstrawberry_client();
    public static String login;
    public static String stats;
    public static String star;
    
    public static void main() throws IOException, InterruptedException{
        
        Socket clientSocket = new Socket("127.0.0.1", 3009);
          
          
          //send data to server
        OutputStream out = clientSocket.getOutputStream();
        PrintWriter writer = new PrintWriter(out, true);
        writer.println(G.ID);
        
        //server is sending back
        InputStream input = clientSocket.getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(input)); 
        login = reader.readLine();
        System.out.println("login(V = good/ X = bad)" + login);
        if (login == "V") {
            System.out.println("login good");
            stats = "V";
            star = "O";
        }   else if (login == "X(ID_not_corret)") {
            stats = "No_Id_found";
            star = "O";
        }   else if (login == "X(NOID)") {
            stats = "Can't_read";
            star = "O";
        }   else {
            System.out.println("login bad");
            stats = "program_can't_login";
            star = "O";
        }
        }

        
}

GUI Code

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.IOException;

import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;
import javax.swing.border.TitledBorder;

public class GUI extends JFrame {
    yellowstrawberry_client yst_c = new yellowstrawberry_client();
    auth a = new auth();
    //login
    public static String ID;
    public static String Code;
    
    JLabel lblTitle; // 타이틀
    JLabel lblName; // 이름
    JLabel lblNumber; // 번호
    JTextField tfName = null; // 이름 입력창
    JTextField tfNumber = null; // 번호 입력창
    JButton btnSave; // 로그인 버튼
    JButton btnReset; // 리셋 버튼
    
    public GUI() {
        init();
        setDisplay();
        showFrame();
    }
    private void init(){

        lblTitle = new JLabel("아이디와 코드를 입력하십시오");
        lblName = new JLabel("ID - 아이디");
        lblNumber = new JLabel("Code - 코드");
        tfName = new JTextField(10);
        tfNumber = new JTextField(10);
        btnSave = new JButton("로그인");
        btnReset = new JButton("이 버튼은(만드는중)");
        btnSave.addActionListener(new ActionListener(){ //익명클래스로 리스너 작성
            public void actionPerformed(ActionEvent e){
                JButton btn = (JButton) e.getSource();
                if(btn.getText().equals("로그인")) {
                    //서버에 아이디, 코드르 줌
                    ID = tfName.getText();
                    Code = tfNumber.getText();
                    if (ID == "") {
                        ID = null;
                    }
                        try {
                            auth.main();
                        } catch (IOException | InterruptedException e2) {
                            // TODO Auto-generated catch block
                            e2.printStackTrace();
                        }
                    while (a.star == "O") {
                        if (a.stats == "V") {
                            btn.setText("로그인중..");
                            System.out.println("login good");
                            return;
                        }   else {
                            btn.setText("로그인");
                            JOptionPane.showMessageDialog(null, "로그인에 실패 하였습니다(" + a.stats + ")", "에러", JOptionPane.ERROR_MESSAGE);
                            return;
                        }
                    }
                    
            }
                
                
                

            
            }});
    }
    private void setDisplay() {
        
        JPanel pnlNorth = new JPanel();
        pnlNorth.add(lblTitle);
        pnlNorth.setBorder(new TitledBorder("North"));
        
        JPanel pnlWest = new JPanel(new GridLayout(0,1,0,10));
        pnlWest.add(lblName);
        pnlWest.add(lblNumber);
        pnlWest.setBorder(new TitledBorder("West"));
        
        JPanel pnlEast = new JPanel(new GridLayout(0,1,0,10));
        pnlEast.add(tfName);
        pnlEast.add(tfNumber);
        pnlEast.setBorder(new TitledBorder("East"));
        
        JPanel pnlSouth = new JPanel();
        pnlSouth.add(btnSave);
        
        pnlSouth.add(btnReset);
        pnlSouth.setBorder(new TitledBorder("South"));
        
        add(pnlNorth, BorderLayout.NORTH);
        add(pnlWest, BorderLayout.WEST);
        add(pnlEast, BorderLayout.EAST);
        add(pnlSouth, BorderLayout.SOUTH);
        
    }

    private void showFrame() {
        setTitle("Yellowstrawberry client");
        pack();
        ImageIcon img = new ImageIcon("C:/user/eunso/OneDrive/Desktop/main.png");
        setIconImage(img.getImage());
        setLocationRelativeTo(null);
        setResizable(false); // 창을 고정
        setVisible(true);
        setSize(400, 250);
        
    }
    public static void main(String[] args){
        new GUI();
        
    }
    public void exit() {
        
    }
    
}

    
    

Code is like that and if I write bbinterjju in gui then it comes like this "Client logined ip : /127.0.0.1 logining ID : bbinterjju 'X' failled(No Id found) in : /127.0.0.1" and in gui it need say like 'login in client!' but it keep saying like 'ERROR THIS CLIENT CAN'T LOGIN THAT' please help me :(