Passing data from one to another

Question

Can anyone help me to correct this Java?

I want to pass the data from login obj JFrame to my mainform class but I do not know how to do it!

Here is my code:

Login.java

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.sql.*;

class Login extends JFrame implements ActionListener{

    private JTextField tfUser;
    private JPasswordField tfPass;
    private JButton btnLogin,btnCancel;
    private JComboBox cbotype;
    private String user,pass;
    private Connection con;
    private Statement stmt;
    private ResultSet rs;
    public Login(){
        super("Login");
        initGUI();
        setLocationRelativeTo(null);
        setVisible(true);
        setResizable(false);
        setDefaultCloseOperation(EXIT_ON_CLOSE);

    }
    public void actionPerformed(ActionEvent e){
        if(e.getSource()==btnLogin) pLogin();
        else if(e.getSource()==btnCancel) cancel();
    }

    public void cancel(){ dispose();
    }
    public void pLogin(){
        if(isLogin())
            setVisible(false);
        System.out.print(user);
    }
    public boolean isLogin(){
        String sms="Welcome!!!",table=cbotype.getSelectedItem().toString();
        pass=tfPass.getText();
        user=tfUser.getText();
        try{
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); 
            String connectionUrl = "jdbc:sqlserver://localhost:1433;" + "databaseName=dbLibrary;user=sa;password=123;";
            Connection con = DriverManager.getConnection(connectionUrl);
            stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
            rs=stmt.executeQuery("SELECT username,password FROM " + table +" Where username='"+ user +"'");     
            if(rs.next ()){
                rs.first();
                if(rs.getString(2).compareTo(pass)==0)
                {   JOptionPane.showMessageDialog(null,sms);
                    return true;
                }else{
                    sms="Incorrect Password! Please, try it again!";
                }
            }else
            {sms="Incorrect User or Password! Please, try again!";}
            JOptionPane.showMessageDialog(null,sms);
        }catch(SQLException e){ e.printStackTrace();
        }catch(ClassNotFoundException e1){e1.printStackTrace();
        }return false;
    }
    public void initGUI(){
        JPanel p1=new JPanel(new FlowLayout());
        p1.add(Interface.title(new JLabel("Login"),"images/login_0.png"));
        //con.add(p1);
        JPanel p2=new JPanel(new GridLayout(3,2));
        p2.add(Interface.label(new JLabel("Type:")));
        p2.add(cbotype=new JComboBox());
        cbotype.addItem("Employee");cbotype.addItem("Patron");
        p2.add(Interface.label(new JLabel("User:")));
        p2.add(tfUser=new JTextField(20));
        p2.add(Interface.label(new JLabel("Password:")));
        p2.add(tfPass=new JPasswordField(20));
        //con.add(p2);

        JPanel p3=new JPanel(new FlowLayout());
        p3.add(Interface.button(btnLogin=new JButton("Login"),"images/login_1.png"));
        p3.add(Interface.button(btnCancel=new JButton("Cancel"),"images/login_2.png"));

        JPanel p=new JPanel(new BorderLayout());
        p.add(p1,"North");
        p.add(p2,"Center");
        p.add(p3,"South");
        add(p);
        pack();

        btnLogin.addActionListener(this);
        btnCancel.addActionListener(this);
    }
    public String getUser(){
        return user;
    }
    public String getPass(){
        return pass;
    }
     public static void main(String[] args) {
        new Login();

    }
}

MainForm.java

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;

public class MainForm extends JFrame implements ActionListener{

private Container con;

    private String user;

    private JButton btnshow;

    public MainForm() {
        initGUI();
        pack();
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }
    public void initGUI(){
        Login login=new Login();
        user=login.getUser();
        //login.dispose();
        System.out.print(user);
        con=getContentPane();
        con.add(btnshow=new JButton("Show"));
        btnshow.addActionListener(this);
    }
    public void actionPerformed(ActionEvent e){
        if(e.getSource()==btnshow) {System.out.print(user); 
        }
    }
    public static void main(String[] args) {
        new MainForm();
    }
}

From MainForm you create a Login instance. Login has public getter for user + pass. You may call the reference to Login form MainForm to get the data. The rest is up to you ... — PeterMmm, Apr 21 '13 at 09:06
*"in JAVA"* No need to put tags in titles, and it is spelled Java *"thx in advance!!!!"* Your thanks would be better expressed by spelling words properly. This is not a text message. — Andrew Thompson, Apr 21 '13 at 09:07

score 1 · Answer 1 · answered Apr 21 '13 at 09:11

1

One way: When you call the Login constructor, is to parse the MainForm instance to it. Your Login class will keep a reference to the MainForm and when you need to let the MainForm know call a method on the MainForm from within the Login class. This is pretty much the same way listeners work...

In your MainForm class

Login login=new Login(this);

In your Login class when you want to let the MainForm know:

this.mainForm.someListenerMethod();

answered Apr 21 '13 at 09:11

NeilA

1,450
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Note that as soon as either frame is closed (while both use `EXIT_ON_CLOSE` close operation), the entire app. will end. – Andrew Thompson Apr 21 '13 at 09:12
@Andrew: True, I never really read his code... – NeilA Apr 21 '13 at 09:53
Ehh (shrugs) neither did I. ;) I just know it is a common problem when using multiple frames, so checked that first. +1 for your approach. – Andrew Thompson Apr 21 '13 at 10:00

score 1 · Answer 2 · edited May 23 '17 at 12:07

See The Use of Multiple JFrames, Good/Bad Practice? The log-in should be a modal JDialog or a JOptionPane. Pop the dialog from the frame, then examine the relevant fields in the next line of code.

Try looking over this code for tips.

import javax.swing.*;
import java.awt.event.*;
import java.awt.*;
import java.sql.*;

public class MainForm extends JFrame implements ActionListener{

private Container con;

    private String user;

    private JButton btnshow;

    public MainForm() {
        initGUI();
        pack();
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
    }

    public void initGUI(){
        Login login=new Login(this);
        user=login.getUser();
        //login.dispose();
        System.out.print(user);
        con=getContentPane();
        con.add(btnshow=new JButton("Show"));
        btnshow.addActionListener(this);
    }
    public void actionPerformed(ActionEvent e){
        if(e.getSource()==btnshow) {System.out.print(user);
        }
    }
    public static void main(String[] args) {
        new MainForm();
    }
}

class Login extends JDialog implements ActionListener{

    private JTextField tfUser;
    private JPasswordField tfPass;
    private JButton btnLogin,btnCancel;
    private JComboBox cbotype;
    private String user,pass;
    private Connection con;
    private Statement stmt;
    private ResultSet rs;
    public Login(Frame f){
        // make it modal
        super(f, true);
        initGUI();
        setLocationRelativeTo(null);
        setVisible(true);
        setResizable(false);
        setDefaultCloseOperation(DISPOSE_ON_CLOSE);

    }
    public void actionPerformed(ActionEvent e){
        if(e.getSource()==btnLogin) pLogin();
        else if(e.getSource()==btnCancel) cancel();
    }

    public void cancel(){ dispose();
    }
    public void pLogin(){
        //if(isLogin())
            setVisible(false);
        System.out.print(user);
    }
    public boolean isLogin(){
        String sms="Welcome!!!",table=cbotype.getSelectedItem().toString();
        // never store passwords as a String, left as an exercise for the user
        pass = new String(tfPass.getPassword());
        user= tfUser.getText();
        try{
            Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
            String connectionUrl = "jdbc:sqlserver://localhost:1433;" + "databaseName=dbLibrary;user=sa;password=123;";
            Connection con = DriverManager.getConnection(connectionUrl);
            stmt=con.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
            rs=stmt.executeQuery("SELECT username,password FROM " + table +" Where username='"+ user +"'");
            if(rs.next ()){
                rs.first();
                if(rs.getString(2).compareTo(pass)==0)
                {   JOptionPane.showMessageDialog(null,sms);
                    return true;
                }else{
                    sms="Incorrect Password! Please, try it again!";
                }
            }else
            {sms="Incorrect User or Password! Please, try again!";}
            JOptionPane.showMessageDialog(null,sms);
        }catch(SQLException e){ e.printStackTrace();
        }catch(ClassNotFoundException e1){e1.printStackTrace();
        }return false;
    }
    public void initGUI(){
        JPanel p1=new JPanel(new FlowLayout());
        p1.add(new JLabel("Login"));
        //con.add(p1);
        JPanel p2=new JPanel(new GridLayout(3,2));
        p2.add(new JLabel("Type:"));
        p2.add(cbotype=new JComboBox());
        cbotype.addItem("Employee");cbotype.addItem("Patron");
        p2.add(new JLabel("User:"));
        p2.add(tfUser=new JTextField(20));
        p2.add(new JLabel("Password:"));
        p2.add(tfPass=new JPasswordField(20));
        //con.add(p2);

        JPanel p3=new JPanel(new FlowLayout());
        p3.add(btnLogin =  new JButton("Login"));
        p3.add(btnCancel = new JButton("Cancel"));

        JPanel p=new JPanel(new BorderLayout());
        // Don't use magic numbers!  There are defined constants
        // for these constraints.
        p.add(p1,BorderLayout.NORTH);
        p.add(p2,BorderLayout.CENTER);
        p.add(p3,BorderLayout.SOUTH);
        add(p);
        pack();

        btnLogin.addActionListener(this);
        btnCancel.addActionListener(this);
    }
    public String getUser(){
        return user;
    }
    public String getPass(){
        return pass;
    }
}

Other tips

Don't extend frame or dialog, just use instances of them.
Swing & AWT GUIs should be created and updated on the Event Dispatch Thread.
Use a consistent and logical indent for code blocks. The indentation of the code is intended to help people understand the program flow.
See further tips in code comments.

Passing data from one to another

Login.java

MainForm.java

2 Answers2

Other tips