Develop Reference

JButton not appearing on JFrame

Following is the code in which the jbutton is not showing on the frame. I have also set visible to true. Even then the button doesn't appear.
class gui{
public static void main(String args[]){
layoutBorder lb=new layoutBorder("check");
}
}
class layoutBorder extends JFrame{
layoutBorder(String title){
super(title);
setLayout(null);
setSize(200, 200);
JButton jb=new JButton("JB");
add(jb);
setVisible(true);
}
}

Don't use a null layout!!!
Swing was designed to be used with layout managers.
Read the section from the Swing tutorial o Layout Managers for more information.
I suggest you download the working examples and play with them. The example will also show you how to better structure your code. Maybe start with the code from How to Use Buttons, which has a simple example that adds 3 buttons to a panel and then the panel to the frame.
Also, class names should start with an upper case character. Have you even seen a class in the API that doesn't??? Learn Java conventions and follow them.

camickr is right. Also, always use the AWT event dispatching thread when an application thread needs to update the GUI.
import javax.swing.*;
import java.awt.*;
import java.lang.*;
public class Gui {
public static void main(String args[]) {
SwingUtilities.invokeLater(() -> {
MyFrame frame = new MyFrame("check");
});
}
}
class MyFrame extends JFrame {
MyFrame(String title){
super(title);
setLayout(new BorderLayout());
setSize(200, 200);
JButton jb = new JButton("JB");
add(jb);
setVisible(true);
}
}

If you want null layouts then you need to set sizes and position by yourself. Using the setLocation and setSize methods.
class gui{
public static void main(String args[]){
layoutBorder lb=new layoutBorder("check");
}
}
class layoutBorder extends JFrame{
layoutBorder(String title){
super(title);
setLayout(null);
setSize(200, 200);
JButton jb=new JButton("JB");
jb.setLocation(10, 10);
jb.setSize(40, 30);
add(jb);
setVisible(true);
}
}

Java FlowLayout

I am writing some Java code that allows the user to see a frame with JLabel, JTextField and JButton.
I want the JLabel to be called "Count" and I have a problem with FlowLayout.
I want the interface to look like this:
Instead, I have this:
This is my code:
package modul1_Interfate_Grafice;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Exercitiu04 implements ActionListener {
private JFrame frame;
private JLabel labelCount;
private JTextField tfCount;
private JButton buttonCount;
private int count = 0;
public void go() {
frame = new JFrame("Java Counter");
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
frame.getContentPane().add(BorderLayout.CENTER, labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
labelCount.add(tfCount);
buttonCount = new JButton("Count");
labelCount.add(buttonCount);
buttonCount.addActionListener(this);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(350, 150);
frame.setLocation(400, 200);
}
#Override
public void actionPerformed(ActionEvent event) {
count++;
tfCount.setText(count + "");
}
public static void main(String[] args) {
Exercitiu04 a = new Exercitiu04();
a.go();
}
}

Solve it.
Instead of labelCount.setLayout(new FlowLayout());` i should have had
frame.setLayout(new FlowLayout());

From description of JLabel class,
JLabel is:
A display area for a short text string or an image, or both.
But here: labelCount.add(tfCount) and here labelCount.add(buttonCount) you're trying to put a textfield and a button into a label. In this case, positions of button and textfield are controlled by FlowLayout but position of the text in the label is not.
Instead of this, you should put all of your elements in common JPanel, like this:
...
frame = new JFrame("Java Counter");
frame.setLayout(new BorderLayout());
JPanel wrapper = new JPanel(); // JPanel has FlowLayout by default
labelCount = new JLabel("Counter");
labelCount.setLayout(new FlowLayout());
wrapper.add(labelCount);
tfCount = new JTextField(count + " ", 10);
tfCount.setEditable(false);
wrapper.add(tfCount);
buttonCount = new JButton("Count");
buttonCount.addActionListener(this);
wrapper.add(buttonCount);
frame.add(BorderLayout.CENTER, wrapper);
...
And, like MasterBlaster said, you should put swing methods in EDT.

There are only two things you should know about FlowLayout:
a) It is a default layout manager of the JPanel component
b) It is good for nothing.
This trivial layout cannot be achieved with FlowLayout.
When doing layouts in Swing, you should familiarize yourself
with some powerful layout managers. I recommend MigLayout and
GroupLayout.
package com.zetcode;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import net.miginfocom.swing.MigLayout;
/*
Simple UI with a MigLayout manager.
Author Jan Bodnar
Website zetcode.com
*/
public class MigLayoutCounterEx extends JFrame {
public MigLayoutCounterEx() {
initUI();
}
private void initUI() {
JLabel lbl = new JLabel("Counter");
JTextField field = new JTextField(10);
JButton btn = new JButton("Count");
createLayout(lbl, field, btn);
setTitle("Java Counter");
setLocationRelativeTo(null);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void createLayout(JComponent... arg) {
setLayout(new MigLayout());
add(arg[0]);
add(arg[1]);
add(arg[2]);
pack();
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
MigLayoutCounterEx ex = new MigLayoutCounterEx();
ex.setVisible(true);
});
}
}
The example is trivial. You just put the three components into the
cells.
Screenshot:

You shouldn't use setSize when dealing with FlowLayout. Instead use pack(). It makes the window just about big enough to fit all your components in. That should tidy things up for you

How to edit JTextField?

I want to write a simple Swing application with a button and a text field at the bottom. I'm using a JTextField but it is not clickable. I searched on the web and SO, but I could not find a solution. In question How to Set Focus on JTextField?, I found the following :
addWindowListener( new WindowAdapter() {
public void windowOpened( WindowEvent e ){
entry.requestFocus();
}
});
but this does not help. In this other question (How do you set a focus on Textfield in Swing?) I found Component.requestFocus() but this does not work either. I also tried
entry.setFocusable(true);
entry.setEditable(true);
entry.setEnabled(true);
without effects. My code:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class StackSample extends JFrame {
public StackSample() {
initUI();
pack();
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
private void initUI() {
JPanel panel = new JPanel(new BorderLayout());
add(panel, BorderLayout.CENTER);
JPanel bottomPanel = new JPanel(new FlowLayout());
panel.add(bottomPanel, BorderLayout.SOUTH);
JButton buttonDraw = new JButton("Draw");
bottomPanel.add(buttonDraw);
JTextField entry = new JTextField();
bottomPanel.add(entry);
setPreferredSize(new Dimension(250, 150));
setLocationRelativeTo(null);
}
private static final long serialVersionUID = 8359448221778584189L;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
MyApp app = new MyApp();
app.setVisible(true);
}
});
}
}

Your JTextField is clickable. The only problem is that it's too small.
This is because you're using FlowLayout, which will make components as small as possible.
One solution is to simply switch to a layout that allows components to fill as much space as possible, such as BoxLayout:
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new BoxLayout(bottomPanel,BoxLayout.X_AXIS));

You haven't specified a size for your JTextField, so it defaults to zero characters wide. Try using the constructor that specifies the number of columns.
Also, what is MyApp? I can't see any evidence that your StackSample is ever created or used.

JButton doesnt show text; fills JFrame

I am trying to make a JFrame with a button in it, but my button doesnt have my wanted text! I'm setting it in the button constructor AND afterwards with setText, but it still doesnt show up! Also, the button fills the whole frame, is there a way to make it not stick to the edges of the JFrame?
import javax.swing.*;
public class main
{
public static void main(String[] args)
{
JFrame mainWindow = new JFrame("8 Game");
mainWindow.setSize(200, 200);
JButton eightButton = new JButton("8");
eightButton.setText("8");
eightButton.setSize(30, 30);
eightButton.setBounds(5, 5, 25, 25);
eightButton.setContentAreaFilled(false);
eightButton.setAction(new buttonAction());
mainWindow.add(eightButton);
mainWindow.setVisible(true);
}
}

Why does it work for me and not you? (with the FlowLayout suggested by others
import java.awt.FlowLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
public class main
{
public static void main(String[] args)
{
JFrame mainWindow = new JFrame("8 Game");
mainWindow.setLayout(new FlowLayout(FlowLayout.CENTER));
mainWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainWindow.setSize(200, 200);
JButton eightButton = new JButton("8");
eightButton.setText("8");
eightButton.setSize(30, 30);
eightButton.setBounds(5, 5, 25, 25);
//eightButton.setAction(new buttonAction());
//eightButton.setContentAreaFilled(false);
mainWindow.add(eightButton);
mainWindow.setVisible(true);
}
}
EDIT
an Action needs a title. If you don't specify one, the button will have no title. If you did this
eightButton.setAction(new buttonAction(), "8");
it would work.

Use a layout manager that respects the component's preferred size
mainWindow.setLayout(new FlowLayout(FlowLayout.CENTER));

Swing components expect a layout manager context when they are added to a window.
The default layout is BorderLayout, which is why you're getting that odd behavior. With only a single element, BorderLayout fills the pane with that element.
Try something like FlowLayout or AbsoluteLayout (or null)
http://docs.oracle.com/javase/tutorial/uiswing/layout/none.html

Use another LayoutManager default frame's layout manager is BorderLayout that if you add a component without specification will add to the center. You can use FlowLayout. See example with SwingUtilities.invokeLater you ensure that will run in EDT.
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame mainWindow = new JFrame("8 Game");
mainWindow .setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainWindow.setLayout(new FlowLayout());
mainWindow.setLocationRelativeTo(null);
JButton eightButton = new JButton("8");
eightButton.setText("8");
eightButton.setContentAreaFilled(false);
eightButton.setAction(new buttonAction());
mainWindow.add(eightButton);
mainWindow.pack();
mainWindow.setVisible(true);
}
});
}
Take a look of more complete correct examples in official tutorials How to use Buttons

How to add components to JDialog

d1=new JDialog();
d1.setSize(200, 100);
t1=new JTextField();
t1.setBounds(10,10,40,20);
d1.add(t1);
I want to add components in JDialog such as TextField, Button...

1) first create a Jpanel
JPanel pan=new JPanel();
pan.setLayout(new FlowLayout());
2) add the components to that JPanel
pan.add(new JLabel("label"));
pan.add(new JButton("button"));
3) create JDialog
JDialog jd=new JDialog();
4) add the JPanel to JDialog
jd.add(pan);

You have to make sure you use no layout manager.
d1.setLayout(null);
By default, a BorderLayout is used. It is great to use layout manager, but the real good ones, that make your windows resizable etc, are hard to understand. Without layout manager, you can specify the bounds as you tried.

You can add components to a JDialog just the way you add to a JFrame since JDialog is a java.awt.Container . You should use a a layout manager or set the layout to null if you want to set the sizes of the components you are adding.

I am not sure of how you really want your components to be laid out but the following snippet should achieve what I am guessing you are trying to do with your current code. Try to work as much as possible with LayoutManager's, Layout constraints, preferred/maximum/minimum sizes and avoid using setLocation/setSize/setBounds.
import java.awt.FlowLayout;
import javax.swing.BorderFactory;
import javax.swing.JDialog;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class Test5 {
protected static void initUI() {
JDialog dialog = new JDialog();
JPanel panel = new JPanel(new FlowLayout(FlowLayout.LEFT));
panel.setBorder(BorderFactory.createEmptyBorder(10, 10, 0, 0));
JTextField textfield = new JTextField(8);
textfield.setBounds(10, 10, 40, 20);
panel.add(textfield);
dialog.add(panel);
dialog.setSize(200, 100);
dialog.setLocationRelativeTo(null);
dialog.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
initUI();
}
});
}
}
You should probably read about LayoutManager's. Take the time to go through it, understand how they work and the different ones that exists. You won't regret spending a few minutes on that.