We Keep Coding

Weird problem with GUI programming in Java

I have made a simple GUI in Java. The problem is, when I add label to the frame before buttons and check-buttons I get weird flickering when hovering over buttons, and GUI doesn't look right. But when I add label after buttons and check-buttons everything is working fine. Why is this happening?
Here is my code:
package javaapplication13;
import java.awt.*;
import javax.swing.*;
public class JavaApplication13 {
public static void main(String[] args) {
ButtonFrame bf = new ButtonFrame();
}
}
class ButtonFrame extends JFrame {
public ButtonFrame() {
JButton b1 = new JButton("1. Dugme");
JButton b2 = new JButton("2. Dugme");
JLabel l1 = new JLabel();
JCheckBox c1 = new JCheckBox("Prvo dugme");
JCheckBox c2 = new JCheckBox("Drugo dugme");
Container cp = getContentPane();
setTitle("Dugme");
setSize(400,400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
this.add(b1);
this.add(b2);
this.add(c1);
this.add(c2);
this.add(l1);
b1.setBounds(20, 30, 90, 20);
b2.setBounds(20,70,90,20);
l1.setBounds(70,120,90,20);
c1.setBounds(120,30,120,20);
c2.setBounds(120,70,120,20);
l1.setText("");
}
}

I did not see the flickering you claim to be getting when I copied and ran your code on my Windows 10 computer with JDK 17. However, when I changed your code and added the label to the frame before adding the buttons and check-boxes (as you stated in your question), I did see "flickering".
Although you have already accepted #Antoniossss answer, it is not recommended to not use a layout manager. Refer to the following excerpts from Doing Without a Layout Manager
Although it is possible to do without a layout manager, you should use a layout manager if at all possible.
If a container holds components whose size is not affected by the container's size or by font, look-and-feel, or language changes, then absolute positioning might make sense.
One of the layout managers that your GUI lends itself to is GridBagLayout, although that is not the only suitable one. The below code shows how. (Note that in the below code I set the text of the JLabel so that you can see it.)
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
public class BtnFrame {
private void createAndDisplayGui() {
JFrame frame = new JFrame("Dugme");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridBagLayout());
createForm(frame.getContentPane());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
private void createForm(Container contentPane) {
if (contentPane instanceof JComponent) {
JComponent jCmpt = (JComponent) contentPane;
jCmpt.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
}
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.LINE_START;
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets.bottom = 5;
gbc.insets.left = 5;
gbc.insets.right = 5;
gbc.insets.top = 5;
JButton b1 = new JButton("1. Dugme");
contentPane.add(b1, gbc);
gbc.gridx = 1;
JCheckBox c1 = new JCheckBox("Prvo dugme");
contentPane.add(c1, gbc);
gbc.gridx = 0;
gbc.gridy = 1;
JButton b2 = new JButton("2. Dugme");
contentPane.add(b2, gbc);
gbc.gridx = 1;
JCheckBox c2 = new JCheckBox("Drugo dugme");
contentPane.add(c2, gbc);
gbc.gridx = 0;
gbc.gridy = 2;
gbc.anchor = GridBagConstraints.CENTER;
JLabel l1 = new JLabel("label");
contentPane.add(l1, gbc);
}
public static void main(String[] args) {
final BtnFrame gui = new BtnFrame();
EventQueue.invokeLater(() -> gui.createAndDisplayGui());
}
}
Here is a screen capture of the application.
When setting the layout manager to null in your code (as #Antoniossss said in his answer), the GUI looks like the below screen capture. (Again, I also set the text of the JLabel so that you can see it.)
As you can see, the two screen captures are practically identical.
For completeness, here is your code, with my changes, that produce the above screen capture. As you can see, I moved the line this.add(l1) and also added the line cp.setLayout(null).
import java.awt.Container;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class ButtonFrame extends JFrame {
public ButtonFrame(){
JButton b1 = new JButton("1. Dugme");
JButton b2 = new JButton("2. Dugme");
JLabel l1 = new JLabel();
JCheckBox c1 = new JCheckBox("Prvo dugme");
JCheckBox c2 = new JCheckBox("Drugo dugme");
Container cp = getContentPane();
cp.setLayout(null); // Added this line.
setTitle("Dugme");
setSize(400,400);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
this.add(l1);
this.add(b1);
this.add(b2);
this.add(c1);
this.add(c2);
// this.add(l1);
b1.setBounds(20, 30, 90, 20);
b2.setBounds(20,70,90,20);
l1.setBounds(70,120,90,20);
c1.setBounds(120,30,120,20);
c2.setBounds(120,70,120,20);
l1.setText("label");
}
public static void main(String[] args) {
ButtonFrame bf = new ButtonFrame();
}
}

It is because of the default LayoutManager which you dont want to use anyway since you are using strict bounds on your components. Remove layout manager with
setLayout(null);
And it will work as intended
public ButtonFrame(){
setLayout(null); //this will do the trick
JButton b1 = new JButton("1. Dugme");
...rest of your code
}

positionnig myJTextField beside JComboBox

I want to creat a palet with many JComboBox. like that :
for(int x=0; x<MAX; x++){
box[x] = new JComboBox(new String[]{"op1", "op2", "op3");
}
at the right of each JComboBox i want to create many JTextField. So, in my palet i will have some think like that:
myJComboBox1 myJTextField
anotherJTextField
anotherJTextField
myJComboBox2 myJTextField
anotherJTextField
anotherJTextField
...
How can i do that please ? I tried by setBounds and other layout like FlowLayout and GridLayout but without success.

GridBagLayout is the best solution. However, if you are new to Swing, it might be a bit over complicated. In that case:
Use GridLayout(0, 2) for the main panel.
Wrap the combobox in a Panel with a border layout and add it to north. Add it to the main panel.
Use another panel with GridLayout(0,1) add your text fields to it and add it to the main panel.
and loop...
Adding sample code:
package snippet;
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.GridLayout;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class BorderLayoutTest extends JFrame {
static private int MAX = 10 ;
public BorderLayoutTest() {
super(BorderLayoutTest.class.getName());
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
initComponents();
}
private void initComponents() {
setLayout(new GridLayout(0, 2));
for(int i = 0; i < MAX; i++) {
add(createComboPanel());
add(createPanelWithTextFields());
}
pack();
}
public Component createComboPanel() {
JPanel panel = new JPanel(new BorderLayout());
panel.add(new JComboBox<>(new String[] { "First Option", "Second Option", "Third Option" }), BorderLayout.NORTH);
return panel;
}
private Component createPanelWithTextFields() {
JPanel panel = new JPanel(new GridLayout(0, 1));
panel.add(new JTextField(30));
panel.add(new JTextField(30));
panel.add(new JTextField(30));
return panel;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override public void run() {
new BorderLayoutTest().setVisible(true);
}
});
}
}

Take a look at GridBagLayout. You can use your window like a table.
myPanel.setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = 1;
JLabel lbl = new JLabel("bla");
myPanel.add(lbl, gbc);
gbc = new GridBagConstraints();
gbc.gridx = 1;
gbc.gridy = 0;
gbc.weightx = 3;
JTextField tf = new JTextField();
myPanel.add(tf, gbc);
gbc = new GridBagConstraints();
gbc.gridx = 1;
gbc.gridy = 1;
gbc.weightx = 3;
JTextField othertf = new JTextField();
myPanel.add(othertf, gbc);
You can even set weights and so on for the GridBagConstraints. It is completly adjusted as table. That will result in something like that:
label textfield
textfield
Just re-read the question. Just replace the JLabels with JComboBoxes and it answers your question a little bit better ;)

Why so much room to the left of my labels in java?

Here is what I have:
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextField;
import javax.swing.ScrollPaneConstants;
import javax.swing.border.LineBorder;
public class Main {
// Field members
static JPanel panel = new JPanel();
static Integer indexer = 1;
static List<JLabel> listOfLabels = new ArrayList<JLabel>();
static List<JTextField> listOfTextFields = new ArrayList<JTextField>();
static JScrollPane scrollPane;
public static void main(String[] args) {
// Construct frame
JFrame frame = new JFrame();
frame.setLayout(new GridBagLayout());
//frame.setPreferredSize(new Dimension(990, 990));
frame.setTitle("My Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Frame constraints
//GridBagConstraints frameConstraints = new GridBagConstraints();
// Construct button
JButton addButton = new JButton("Add");
addButton.addActionListener(new ButtonListener());
// Add button to frame
//frameConstraints.gridx = 0;
//frameConstraints.gridy = 0;
//frame.add(addButton, frameConstraints);
frame.add(addButton);
// Construct panel
panel.setPreferredSize(new Dimension(1000, 1000));
panel.setLayout(new GridBagLayout());
panel.setBorder(LineBorder.createBlackLineBorder());
scrollPane = new JScrollPane(panel, ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED, ScrollPaneConstants.HORIZONTAL_SCROLLBAR_AS_NEEDED);
scrollPane.setPreferredSize(new Dimension(600, 600));
// Add panel to frame
//frameConstraints.gridx = 0;
//frameConstraints.gridy = 1;
//frameConstraints.weighty = 1;
//frame.add(panel, frameConstraints);
frame.add(scrollPane);
// Pack frame
frame.pack();
// Make frame visible
frame.setVisible(true);
}
static class ButtonListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent arg0) {
// Clear panel
panel.removeAll();
// Create label and text field
//JTextField jTextField = new JTextField();
//jTextField.setSize(100, 200);
//listOfTextFields.add(jTextField);
listOfLabels.add(new JLabel("" + indexer));
// Create constraints
//GridBagConstraints textFieldConstraints = new GridBagConstraints();
GridBagConstraints labelConstraints = new GridBagConstraints();
// Add labels and text fields
for (int i = 0; i < indexer; i++) {
// Text field constraints
//textFieldConstraints.gridx = 1;
//textFieldConstraints.fill = GridBagConstraints.HORIZONTAL;
//textFieldConstraints.weightx = 0.5;
//textFieldConstraints.insets = new Insets(10, 10, 10, 10);
//textFieldConstraints.gridy = i;
// Label constraints
labelConstraints.gridx = 0;
labelConstraints.gridy = i;
labelConstraints.insets = new Insets(0, 0, 0, 0);
// Add them to panel
panel.add(listOfLabels.get(i), labelConstraints);
//panel.add(listOfTextFields.get(i), textFieldConstraints);
}
// Align components top-to-bottom
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = indexer;
c.weighty = 1;
c.ipady = 0;
panel.add(new JLabel(), c);
System.out.println("indexer is " + indexer);
// Increment indexer
indexer++;
panel.updateUI();
if(indexer ==2){
listOfLabels.set(0, new JLabel("Test"));
}
}
private int getWidth() {
// TODO Auto-generated method stub
return 0;
}
}
}
Here is the output:
What Am I doing wrong? I want the labels to be justified all the way to the left. I don't have any padding set to the left so I am confused.
FYI, I found this code on stackoverflow and my goal is to have labels that I can dynamically add and update, hence I commented out the textboxes.

Don't call setPreferredSize on the scroll pane, this isn't what you should setting, use GridBagConstraints weightx/y and fill properties.
Don't call updateUI, it doesn't do what you think it does, call revalidate instead, if you have to
The main reasons you're having problems is
You're call setPreferredSize on the panel. When adding components to a GridBagLayout, it will attempt to lay out components around the centre of the container
You've not specified a weightx or anchor property for the GridBagConstraints when adding the labels

Java GridBagLayout - How to position my components gap-less and one by one?

I'm using GridBagLayout to place my GUI components by the following code, wanting the components lay one by one in a column, without any gaps :
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TestGUI extends JFrame{
public TestGUI(){
JPanel bigPanel = new JPanel(new GridBagLayout());
JPanel panel_a = new JPanel();
JButton btnA = new JButton("button a");
panel_a.add(btnA);
JPanel panel_b = new JPanel();
JButton btnB = new JButton("button b");
panel_b.add(btnB);
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = 0;
c.weighty = 1D;
c.fill = GridBagConstraints.HORIZONTAL;
c.anchor = GridBagConstraints.NORTH;
bigPanel.add(panel_a, c);
c.gridx = 0;
c.gridy = 1;
c.fill = GridBagConstraints.HORIZONTAL;
bigPanel.add(panel_b, c);
this.add(bigPanel);
}
public static void main(String[] args) {
TestGUI gui = new TestGUI();
gui.setVisible(true);
gui.pack();
}
}
I wish the panels will be shown one by one in the column. but now i got this :
As i am going to add some more components in the bigPanel, and required some more customization to the layout, so i need to use GridBagLayout instead of other Layout.

You need to add an extra component so that it will fill the rest of the available space and push the two button-panels to the top. When you will add more components, you can of course remove that component.
Another option (without requiring an extra component) would have been to set weighty=1.0 for the panel_b and anchor=NORTH, but then you would have to change that when you add more components.
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class TestGUI extends JFrame {
public TestGUI() {
JPanel bigPanel = new JPanel(new GridBagLayout());
JPanel panel_a = new JPanel();
JButton btnA = new JButton("button a");
panel_a.add(btnA);
JPanel panel_b = new JPanel();
JButton btnB = new JButton("button b");
panel_b.add(btnB);
GridBagConstraints c = new GridBagConstraints();
c.gridwidth = GridBagConstraints.REMAINDER;
c.fill = GridBagConstraints.HORIZONTAL;
c.weightx = 1.0;
bigPanel.add(panel_a, c);
bigPanel.add(panel_b, c);
c.weighty = 1.0;
// Temporary panel to fill the rest of the bigPanel
bigPanel.add(new JPanel(), c);
this.add(bigPanel);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
TestGUI gui = new TestGUI();
gui.pack();
gui.setVisible(true);
}
});
}
}

java: dynamically generated textbox by clicking on button

I have cretaed textfields and labels on clicking 'add' button. I have given x and y coordinates, but textbox appearing is in improper manner.
how to correct it? and also how to increase width of textbox ???
import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.border.LineBorder;
public class SS
{
// Field members
static JPanel panel = new JPanel();
static Integer indexer = 1;
static List<JLabel> listOfLabels = new ArrayList<JLabel>();
static List<JTextField> listOfTextFields = new ArrayList<JTextField>();
public static void main(String[] args)
{
// Construct frame
JFrame frame = new JFrame();
frame.setLayout(new GridBagLayout());
frame.setPreferredSize(new Dimension(800, 800));
frame.setTitle("My Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Frame constraints
GridBagConstraints frameConstraints = new GridBagConstraints();
// Construct button
JButton addButton = new JButton("Add");
addButton.addActionListener(new ButtonListener());
// Add button to frame
frameConstraints.gridx = 0;
frameConstraints.gridy = 0;
frame.add(addButton, frameConstraints);
// Construct panel
panel.setPreferredSize(new Dimension(400, 400));
panel.setLayout(new GridBagLayout());
panel.setBorder(LineBorder.createBlackLineBorder());
// Add panel to frame
frameConstraints.gridx = 0;
frameConstraints.gridy = 1;
frameConstraints.weighty = 20;
frame.add(panel, frameConstraints);
// Pack frame
frame.pack();
// Make frame visible
frame.setVisible(true);
}
static class ButtonListener implements ActionListener
{
#Override
public void actionPerformed(ActionEvent arg0)
{
// Clear panel
panel.removeAll();
// Create label and text field
listOfTextFields.add(new JTextField());
listOfLabels.add(new JLabel("Name " + indexer));
// Create constraints
GridBagConstraints textFieldConstraints = new GridBagConstraints();
GridBagConstraints labelConstraints = new GridBagConstraints();
// Add labels and text fields
for(int i = 0; i < indexer; i++)
{
// Text field constraints
textFieldConstraints.gridx = 20;
textFieldConstraints.gridy = i;
// Label constraints
labelConstraints.gridx = 1;
labelConstraints.gridy = i;
// Add them to panel
panel.add(listOfTextFields.get(i), textFieldConstraints);
panel.add(listOfLabels.get(i), labelConstraints);
}
// Align components top-to-bottom
GridBagConstraints c = new GridBagConstraints();
c.gridx = 0;
c.gridy = indexer;
c.weighty = 1;
panel.add(new JLabel(), c);
// Increment indexer
indexer++;
}
}
}

To get the frame to refresh with the text box you need to call pack at the bottom of your actionPerformed method.
frame.pack();
For this you need to have frame as a class variable.
static JFrame frame;
For the size the grid bag layout will override your setSize so you can give it a weight and make it stretch to fill in the space. This can go just after your other textFieldContraints calls.
textFieldConstraints.weightx = 1;
textFieldConstraints.fill = GridBagConstraints.HORIZONTAL;
This should make the text boxes appear when you hit the button and take up the box.

Increase width of textfield.
listOfTextFields.add(new JTextField(null,10));