Gridbag layout not showing

[mitchell bat]

Hey guys,

I'll try to keep this as short and sweet as possible. I've created a window and now I want to add buttons, text fields, password field and labels to a frame but when I try to use grid bag layout for some reason it's not working. I've tried going to afew tutorials but they don't really help and I can't seem to understand where i'm going wrong. Can you guys take a look and let me know where i'm going wrong.

import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;

public class Login {

    public static void main (String [] args){

        //create new labels
        JLabel username = new JLabel("Username");
        JLabel password = new JLabel("Password");

        //create a new button
        JButton button = new JButton("Login");

        //create a new frame
        JFrame frame = new JFrame();

        //create a password field
        JPasswordField passwordField = new JPasswordField();

        //create a text field for the username
        JTextField jTextField = new JTextField(30);

        //set the conditions of the frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //set the conditions of the frame
        frame.setTitle("Testing");
        frame.setSize(400,400);
        frame.setVisible(true);

        //layout
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();

        constraints.gridx = 0;
        constraints.gridy = 0;
        constraints.ipadx = 5;
        constraints.ipady = 5;
        panel.add(new JButton("Login"), constraints);

        //set the size of the button
        button.setSize(100,100);
    }

}

[Campbell Ritchie]

Don't combine setSize and a layout. Use the fill fields of the cnstraints instead.
Don't use grid bag constraints if you can use something like Cay Horstmann's GBC class. Have a look at the tutorial he links to
Don't add things after the setVisible call. Move the setVisible call to the last line. What is happening is that you are making the GUI visible before you add the button, so the version with the button never appears.

[Piet Souris]

at least as important: don't forget to add the panel to the frame.

[Rob Camick]

I've tried going to afew tutorials but they don't really help

Show us the links to the tutorials that you are using and point out the sections from the tutorial that you don't understand.

If you don't understand the tutorial, why do you think you will understand what we suggest? We can't guess what you find confusing.

So the idea of using a tutorial is to start with working code and then make changes. When something stops working you know what you just changed and then you can ask a specific question about the change you just made.

[mitchell bat]

This is my redo let out as logically as I can but once again the panel with the labels and fields isn't showing up

import sun.rmi.runtime.Log;

import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;

import static com.sun.javafx.fxml.expression.Expression.add;

public class Login {

    public static void main (String [] args){

        //create new labels
        JLabel username = new JLabel("Username");
        JLabel password = new JLabel("Password");

        //create a new button
        JButton button = new JButton("Login");

        //create a new frame
        JFrame frame = new JFrame();

        //create a password field and username field
        JPasswordField passwordField = new JPasswordField(30);
        JTextField textField = new JTextField(30);

        //create a text field for the username
        JTextField jTextField = new JTextField(30);

        //set the conditions of the frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //set the conditions of the frame
        frame.setTitle("Testing");
        frame.setSize(400,400);
        frame.setVisible(true);

        //layout
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();

        //adding the jpanel to the frame
        frame.setLayout(new GridBagLayout());

        //adding the
        panel.add(button);
        panel.add(username);
        panel.add(password);
        panel.add(passwordField);

        constraints.weighty = 1;
        constraints.weightx = 0.1;

        //row 1
        constraints.gridx = 0;
        constraints.gridy = 0;
        add(username, constraints);

        //row 2
        constraints.gridx = 0;
        constraints.gridy = 1;
        add(password, constraints);

        //row 3
        constraints.gridx = 1;
        constraints.gridy = 0;
        add(passwordField, constraints);

        //row 4
        constraints.gridx = 1;
        constraints.gridy = 1;
        add(passwordField, constraints);
    }
}

[Piet Souris]

hi Mitchell,

the problem is: the devil is in the details.

You seem to know the concepts involved: creating a frame, and a JPanel with a GridbagLayout, and setting your constraints. The problem is: how do you use all these things in the correct way?

For instance: you write (lines 42 and 43):

//adding the jpanel to the frame
        frame.setLayout(new GridBagLayout());

But that code does not add a panel to the frame at all.

Then you add many components to your panel, okay, but then these components are again added (see lines 46-49 and 57 and farther). To what are you adding these components (from line 57)?

So, create your JPanel, with GridBagLayout, add all your components to it, with the correct constraints, then create your frame and add that panel to it, with
frame.add(panel).

Getting this contraints exactly as they should be can be a bit of a hussle, but then again, experiment as much as you can, with the API at hand.

Keep to this simple scheme. Succes!

[mitchell bat]

Ah.... I see what I did....

//layout
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();

        //adding the jpanel to the frame
        frame.setLayout(new GridBagLayout());

This is what I have so far now, don't tell me where the mistakes are but point out what is wrong so I can find it. I'm starting to get hooked on programming and I want to know everything.

import sun.rmi.runtime.Log;




import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;

import static com.sun.javafx.fxml.expression.Expression.add;

public class Login {

    public static void main (String [] args){

        //create new labels
        JLabel username = new JLabel("Username");
        JLabel password = new JLabel("Password");

        //create a new button
        JButton button = new JButton("Login");

        //create a new frame
        JFrame frame = new JFrame();

        //create a password field and username field
        JPasswordField passwordField = new JPasswordField(30);
        JTextField textField = new JTextField(30);

        //create a text field for the username
        JTextField jTextField = new JTextField(30);

        //set the conditions of the frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //set the conditions of the frame
        frame.setTitle("Testing");
        frame.setSize(400,400);
        frame.setVisible(true);

        //layout
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();

        //adding the jpanel to the frame
        frame.setLayout(new GridBagLayout());

        //set constraints
        constraints.weighty = 1;
        constraints.weightx = 0.1;

        //row 1
        constraints.gridx = 0;
        constraints.gridy = 0;
        add(username, constraints);

        //row 2
        constraints.gridx = 0;
        constraints.gridy = 1;
        add(password, constraints);

        //row 3
        constraints.gridx = 1;
        constraints.gridy = 0;
        add(passwordField, constraints);

        //row 4
        constraints.gridx = 1;
        constraints.gridy = 1;
        add(passwordField, constraints);

        //adding components to the Jpanel
        username.add(panel);
        password.add(panel);
        button.add(panel);
        passwordField.add(panel);
        textField.add(panel);

        frame.add(panel);
    }
}

[Piet Souris]

If you are using an IDE, then you'll see that the IDE reports many errors.
Why do you set a GridbagLayout for your frame?
you are (at the end of the program) adding your components like this:  component.add(panel). Does that seem right?

And, as Campbeel wrote (although it does not matter much): first make your frame ok, and only then make it visible.

Yiou see: many details that need to be correct. So, code as much as you can, but with the API's at hand, and give the Oracle tutorials a thorough read! There's no other way. But don't worry: it is quite a pleasent way!

[mitchell bat]

Isn't that the correct way to add components to the panel?

component.add(panel);

?

Also do you set the gridbaglayout to the panel or to the frame?

[Piet Souris]

And, have you corrected the errors and run your program? What output did you get?
Can you answer your own questions now?

[Fred Kleinschmidt]

Pay attention to what others have told you. Make sure the frame.setVisible(true) call is made AFTER you add the panel to the frame.
Don't set a size on the button - let it be its preferred size.

And you are calling  

textField.add(panel);

That is backward. you want to add the textField to the panel, not add the panel to the textField.

[mitchell bat]

Hey guys, just wanted to say I got it!

I read through it all and figured out where I was going wrong.
1. As Fred Kleinschmidt said I was adding the panel to the components and not the component to the panel
2. I set the visibility to true in the wrong part of the code
3. Gridbag layout was wrong

Here is my revised code but now it's time to play around with the gridbaglayout so I can master it!

import sun.rmi.runtime.Log;

import javax.swing.*;
import javax.swing.border.Border;
import java.awt.*;

import static com.sun.javafx.fxml.expression.Expression.add;

public class Login {

    public static void main (String [] args){

        //create new labels
        JLabel username = new JLabel("Username");
        JLabel password = new JLabel("Password");

        //create a new button
        JButton button = new JButton("Login");

        //create a new frame
        JFrame frame = new JFrame();

        //create a password field and username field
        JPasswordField passwordField = new JPasswordField(30);
        JTextField textField = new JTextField(30);

        //create a text field for the username
        JTextField jTextField = new JTextField(30);

        //set the conditions of the frame
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //set the conditions of the frame
        frame.setTitle("Testing");
        frame.setSize(400,400);

        //layout
        JPanel panel = new JPanel(new GridBagLayout());
        GridBagConstraints constraints = new GridBagConstraints();

        //adding the jpanel to the frame
        frame.setLayout(new GridBagLayout());

        //adding components to the Jpanel
        //the issue here was I was adding the panel to the components and not to components to the panel
        //old code looked like this         username.add(panel); password.add(panel);   etc
        //when it should look how it does below
        panel.add(username);
        panel.add(password);
        panel.add(button);
        panel.add(passwordField);
        panel.add(textField);

        //adds the panel to the frame
        frame.add(panel);

        //set weights
        constraints.weighty = 1;
        constraints.weightx = 0.1;

        //row 1
        constraints.gridx = 0;
        constraints.gridy = 0;
        constraints.anchor = GridBagConstraints.FIRST_LINE_START;
        frame.add(username, constraints);

        frame.setVisible(true);
    }
}