Develop Reference

Swing JLabel missing characters

So I have come across a peculiar problem.
My interface is just a single label, and a JSlider.
My code(stripped):
import javax.swing.*;
import java.awt.*;
public class Broken {
JLabel value = new JLabel();
JSlider slider = new JSlider(0, 255, 0);
public Broken() {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JPanel panel = new JPanel();
value.setText("Some Value");
panel.add(value);
JFrame frame = new JFrame("Frame Name");
frame.setLayout(new GridLayout(2, 1));
frame.add(panel);
frame.add(slider);
frame.pack();
frame.setVisible(true);
}
});
}
public static void main(String[] args) {
new Broken();
}
}
What happens is the label doesn't show up. If I resize the screen from the right to the smallest possible, suddenly the text appears, and it will stay there if I resize back to what it was. I have no idea what's happening, this truly seems like a bug to me.
Before and after resizing screenshots:

Despite your efforts, you're not on the EventDispatchThread when you're creating your JLabel (or JSlider, for that matter). To test, I subclassed JLabel just see if the code was on the EDT when it's constructor is called:
import java.awt.*;
import javax.swing.*;
public class Broken {
JLabel value = new XLabel(); // called before constructor, so not on EDT
JSlider slider = new JSlider(0, 255, 0); // same here
public Broken() {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
JPanel panel = new JPanel();
value.setText("Some Value");
panel.add(value);
JFrame frame = new JFrame("Frame Name");
frame.setLayout(new GridLayout(2, 1));
frame.add(panel);
frame.add(slider);
frame.pack();
frame.setVisible(true);
}
});
}
public static void main(String[] args) {
new Broken();
}
class XLabel extends JLabel {
public XLabel() {
super();
System.out.println("EDT? " + SwingUtilities.isEventDispatchThread());
}
}
}
To fix, place the invokeLater call in main, so as to wrap the entire construction of your class onto the EDT:
import java.awt.*;
import javax.swing.*;
public class Broken2 {
JLabel value = new JLabel();
JSlider slider = new JSlider(0, 255, 0);
public Broken2() {
JPanel panel = new JPanel();
value.setText("Some Value");
panel.add(value);
JFrame frame = new JFrame("Frame Name2");
frame.setLayout(new GridLayout(2, 1));
frame.add(panel);
frame.add(slider);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
// Generally the proper way. Create Whole app on EDT
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new Broken2();
}
});
}
}

JPanel does not appear when i try to add it to ContentPane

I'm having a problem trying to change JPanels by using buttons. I have a JFrame with 2 panels, 1 of them is for the buttons, which i want them to always be showed. The other one is the one that i will be switching everytime i press one ot the buttons of the other panel. The problem is that everytime i press them nothing really ever displays, i keep my buttons but the other panel that i call does not appear.
Code for one of the buttons is as follows
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
ReparacaoPanel r = new ReparacaoPanel(this, this.jPanel1);
this.getContentPane().remove(this.jPanel1);
this.getContentPane().add(r);
//this.setContentPane(r);
this.visiblePanel.setVisible(false);
this.visiblePanel = r;
this.pack();
this.setVisible(true);
r.setLocation(200, 200);
this.getContentPane().revalidate();
this.repaint();
}
If i try to use "this.setContentPane(r);" (it sets the frame to only show the panel) the panel shows. But when i try to call it as i'm trying to do in the code above nothing is showed apart from the panel that has the buttons.
I have no idea what i'm doing wrong, it does not seem to be a problem with the JPanel that i'm trying to call as it shows if used alone.
Anyone can help me out?

Consider this working example for switching manually between panels. Which produces this output.
.........
Some tiny NumberPanel
Every new instance shows another number in the center.
import javax.swing.JPanel;
public class NumberPanel extends JPanel {
private static int counter = 0;
public NumberPanel() {
setLayout(new BorderLayout(0, 0));
JLabel lblNewLabel = new JLabel("" + counter++);
lblNewLabel.setHorizontalAlignment(SwingConstants.CENTER);
add(lblNewLabel);
}
}
Setting up a frame
private void initialize() {
frame = new JFrame();
frame.setBounds(100, 100, 450, 300);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel();
frame.getContentPane().add(panel, BorderLayout.SOUTH);
JButton btnNewButton = new JButton("New button");
btnNewButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
frame.getContentPane().remove(numberPanel);
numberPanel = new NumberPanel();
frame.getContentPane().add(numberPanel, BorderLayout.CENTER);
frame.pack();
}
});
panel.add(btnNewButton);
numberPanel = new NumberPanel();
frame.getContentPane().add(numberPanel, BorderLayout.CENTER);
frame.pack();
}
Testprogram
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TestPanelSwitch {
private JFrame frame;
private NumberPanel numberPanel;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
TestPanelSwitch window = new TestPanelSwitch();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
public TestPanelSwitch() {
initialize();
}
private void initialize() {
// see above
}
}
Back to the Question
I think you only need to pack your frame, like in the anonymous ActionListener.
frame.getContentPane().remove(numberPanel);
numberPanel = new NumberPanel();
frame.getContentPane().add(numberPanel, BorderLayout.CENTER);
frame.pack();
EDIT
As leonidas mentioned it is also possible to revalidate the frame. This requires only to replace the upper call to pack by theese.
frame.invalidate();
frame.validate();

How do i make next button go to next Frame? GUI

How do I make the next button go to the next Frame in this GUI? I need to have it where I can click next to display 20 more details:
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class FilledFrameViewer
{
public static void main(String[] args)
{
JFrame frame = new JFrame();
/*JButton button = new JButton*/
JButton nextButton = new JButton("NEXT");
JLabel label = new JLabel("Frame 1.");
JPanel panel = new JPanel();
panel.add(nextButton);
panel.add(label);
frame.add(panel);
final int FRAME_WIDTH = 300;
final int FRAME_HEIGHT = 100;
frame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
frame.setTitle("A frame with two components");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}

If you want to hide or show the frame, you can use like this
JFrame f1 = new JFrame("Frame 1");
JFrame f2 = new JFrame("Frame 2");
to hide f1, call f1.setVisible(false);
to show f2, call f2.setVisible(true);

A bit unclear. Do you want to move a JButton to another JFrame? I don't think you can manage that without dynamic programming or such (I guess?).
You should look through a tutorial of the Swing components from Oracle http://docs.oracle.com/javase/tutorial/uiswing/
And see your comments. I agree having multiple JFrame is a bad habit.
Edit
Use the eventlistner (see other answer) and make it follow a switch case? Then there you can make it display like a dialog or change a JLable inside your JFrame?
Dialog tutorial here: http://docs.oracle.com/javase/tutorial/uiswing/components/dialog.html.
I think you should go with a lable and change it's text.
JButton nextButton = new JButton("Next");
nextButton.addActionListener(new ActionListner(
private int counter = 0;
public void actionPerformed(ActionEvent e) {
counter++;
switch(counter){
case 1: somelable.setText("Your text here");
};
}));
I wrote this on free hand but I guess something like this would work?

You have to edit the codes in your next frame...
Example for your NextFrame,
public class NextFrame
public static void main(String[] args)
{
private static FilledFrameViewer parentFrame; //ADD THIS FOR CONNECTION TO FIRST FRAME
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
NextFrame frame = new NextFrame(null); //CHANGES MADE HERE
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
public NextFrame(FilledFrameViewer f) { //CHANGES MADE HERE
this.parentFrame = f; //CHANGES MADE HERE
setTitle("Personal Assistant");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 450, 300);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
contentPane.setLayout(null);

Ah, Yes...and also you'll have to add some things in the Next button...
Example:
btnNext = new JButton();
btnNext.addItemListener(new ItemListener() {
public void itemStateChanged(ItemEvent e) {
goNext();
{
private void goNext(){
NextFrame nextframe= new NextFrame(null);
nextframe.setVisible(true);
}
}
});

Working with JFrames

hi I'm basically give up. Ok so this is what I am trying to do. So far I have written code to create a JFrame which contains a text field and combo box. The code is supposed to calculate the area of an input in the text field depending on what shape is selected from the combo box and output the result on the JFrame!
Here's is what the output should look like
And here is my code so far. it's a bit messed up but any help would be much appreciated. Thanks in advance
import javax.swing. *;
import java.awt.event. *;
import java.awt.FlowLayout;
import java.lang.Math;
public class AreaFrame3 extends JFrame
{
double Area;
double input;
public static void main(String[]args)
{
//Create array containing shapes
String[] shapes ={"(no shape selected)","Circle","Equilateral Triangle","Square"};
//Use combobox to create drop down menu
JComboBox comboBox=new JComboBox(shapes);
JLabel label1 = new JLabel("Select shape:");
JPanel panel1 = new JPanel(new FlowLayout()); //set frame layout
JLabel label2 = new JLabel("(select shape first)");
JTextField text = new JTextField(10); //create text field
text.setEnabled(false);
panel1.add(label1);
panel1.add(comboBox);
panel1.add(label2);
panel1.add(text);
JFrame frame=new JFrame("Area Calculator Window");//create a JFrame to put combobox
frame.setLayout(new FlowLayout()); //set layout
frame.add(panel1);
frame.add(text);
//JButton button = new JButton("GO"); //create GO button
//frame.add(button);
//set default close operation for JFrame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
//set JFrame ssize
frame.setSize(400,250);
//make JFrame visible. So we can see it
frame.setVisible(true);
// public void actionPerformed(ActionEvent e)
//{
}
public void AreaCalc()
{
JButton button = new JButton("GO"); //create GO button
frame.add(button);
button.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent e)
{
int input = double.parseDouble(text.getText());
if(e.getSource() == button)
{
String shape = (String).comboBox.getSelectedItem();
if(shape == "(no shape selected)")
{
text.setEnabled(false);
}
else{
text.setEnabled(true);
}
if(input > 1 && shape == "Circle")
{
// label2.getText() = "Enter the radius of the circle: ";
Area = (Math.PI * (input * input));
}
}
else{}
}
}
);
}
}

I try to understand what you did here:
panel1.add(label1);
panel1.add(comboBox);
panel1.add(label2);
panel1.add(text); // <---
JFrame frame=new JFrame("Area Calculator Window");//create a JFrame to put combobox
frame.setLayout(new FlowLayout()); //set layout
frame.add(panel1);
frame.add(text); // <---
Especially frame.add(text); and panel1.add(text);. Don't add text to JFrame. Use JPanel.
Further,
public class AreaFrame3 extends Frame
Use public class AreaFrame3 extends JFrame so you don't need create additional JFrame:
JFrame frame=new JFrame("Area Calculator Window");
Something like:
super.setLayout(new FlowLayout()); //set layout
super.add(panel1);
super.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
super.pack();
//set JFrame ssize
super.setSize(400,250);
//make JFrame visible. So we can see it
super.setVisible(true);
At last Ill give you some tamplate to start with (that will help you):
public class FrameExmpl extends JFrame{
private static final long serialVersionUID = 1L;
private JTabbedPane tabbedPane;
private JPanel topPanel;
private JTextField txtf_loadDS_;
public static int valueInt = 0; // responsible for Task status updating
public static Boolean isFinish = false;
public static void main(String[] args) throws ClassNotFoundException, InstantiationException, IllegalAccessException, UnsupportedLookAndFeelException{
UIManager.setLookAndFeel( "com.sun.java.swing.plaf.windows.WindowsLookAndFeel" );
FrameExmpl UI_L = new FrameExmpl();
UI_L.buildGUI();
UI_L.setVisible(true);
}
public void buildGUI(){
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
dispose();
}
});
setSize(435, 225);
setLocation(285, 105);
setResizable(false);
topPanel = new JPanel();
topPanel.setLayout(new BorderLayout());
getContentPane().add(topPanel);
txtf_loadDS_ = new JTextField();
txtf_loadDS_.setBounds(22, 22, 382, 25);
topPanel.add(txtf_loadDS_);
finishBuildGUI();
}
public void finishBuildGUI(){
tabbedPane = new JTabbedPane();
topPanel.add(tabbedPane, BorderLayout.CENTER);
}
}

There are multiple issues with this application such as extending from Frame rather than JFrame & attempting to assign an int from Double.parseDouble. I would recommend that you start again building a small but working application and incrementally add functionality, this way errors are easier to fix.

How can I properly center a JPanel ( FIXED SIZE ) inside a JFrame?

Hi all!
I'm trying to solve an -apparently- simple problem, but I cannot fix it.
I'm working on a sample application with Java/Swing libraries;
I have a JFrame and a JPanel.
I just want to achieve the following objectives:
JPanel MUST be centered inside the JFrame.
JPanel MUST have ALWAYS the size that is specified with
setPreferredSize() method. It MUST NOT be resized under this size.
I tried by using a GridBagLayout: it's the ONLY way I can do it.
See the sample below:
/* file StackSample01.java */
import java.awt.*;
import javax.swing.*;
public class StackSample01 {
public static void main(String [] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setPreferredSize(new Dimension(100, 100));
panel.setBackground(Color.RED);
frame.setLayout(new GridBagLayout());
frame.add(panel, new GridBagConstraints());
frame.setSize(new Dimension(200, 200));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
Here a screenshot:
I would not use a GridBagLayout to do a thing too simple.
I tried a simplest solution, by using a Box, but this does not work:
Sample code:
/* file StackSample02.java */
import java.awt.*;
import javax.swing.*;
public class StackSample02 {
public static void main(String [] args) {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
panel.setPreferredSize(new Dimension(100, 100));
panel.setBackground(Color.RED); // for debug
panel.setAlignmentX(JComponent.CENTER_ALIGNMENT); // have no effect
Box box = new Box(BoxLayout.Y_AXIS);
box.add(Box.createVerticalGlue());
box.add(panel);
box.add(Box.createVerticalGlue()); // causes a deformation
frame.add(box);
frame.setSize(new Dimension(200, 200));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
Here a screenshot,
Any ideas? Thanks to all :-)

BoxLayout can pretty to hold your setXxxSize(), then just add panel.setMaximumSize(new Dimension(100, 100));
and your output would be
Removed by setMinimumSize(notice if Container has greater size as ... )
import java.awt.*;
import javax.swing.*;
public class CustomComponent12 extends JFrame {
private static final long serialVersionUID = 1L;
public CustomComponent12() {
Box box = new Box(BoxLayout.Y_AXIS);
box.setAlignmentX(JComponent.CENTER_ALIGNMENT);
box.add(Box.createVerticalGlue());
box.add(new CustomComponents12());
box.add(Box.createVerticalGlue());
add(box);
pack();
setTitle("Custom Component Test / BoxLayout");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setMaximumSize(getMinimumSize());
setMinimumSize(getMinimumSize());
setPreferredSize(getPreferredSize());
setLocation(150, 150);
setVisible(true);
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
CustomComponent12 main = new CustomComponent12();
}
};
javax.swing.SwingUtilities.invokeLater(r);
}
}
class CustomComponents12 extends JPanel {
private static final long serialVersionUID = 1L;
#Override
public Dimension getMinimumSize() {
return new Dimension(100, 100);
}
#Override
public Dimension getMaximumSize() {
return new Dimension(100, 100);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(100, 100);
}
#Override
public void paintComponent(Graphics g) {
int margin = 10;
Dimension dim = getSize();
super.paintComponent(g);
g.setColor(Color.red);
g.fillRect(margin, margin, dim.width - margin * 2, dim.height - margin * 2);
}
}

First of all, thanks to all.
I reply another time to my own question, to show everyone the choice I have made.
See the sample code below;
As you can see, I have included only minimal steps which are absolutely necessary to achieve the goal.
/* file StackResponse.java */
import java.awt.*;
import javax.swing.*;
public class StackResponse {
public static void main(String [] args) {
JPanel panel = new JPanel();
Dimension expectedDimension = new Dimension(100, 100);
panel.setPreferredSize(expectedDimension);
panel.setMaximumSize(expectedDimension);
panel.setMinimumSize(expectedDimension);
panel.setBackground(Color.RED); // for debug only
Box box = new Box(BoxLayout.Y_AXIS);
box.add(Box.createVerticalGlue());
box.add(panel);
box.add(Box.createVerticalGlue());
JFrame frame = new JFrame();
frame.add(box);
frame.setSize(new Dimension(200, 200));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setMinimumSize(frame.getMinimumSize()); // cannot be resized-
frame.setVisible(true);
}
}
Here you can see a screenshot.
Problem solved.
Many thanks again to all.
IT

create a panel by name "FixedPanel" with GridBagLayout and set preferred size to frame size
then add your frame into FixedPanel.
Frame = new JFrame("CenterFrame");
Frame.setLocation(0, 0);
Frame.setSize(new Dimension(400,400));//dim
JPanel FixedPanel = new JPanel(new GridBagLayout());
FixedPanel.setPreferredSize(Frame.getSize());
JPanel myPanel = new JPanel();
myPanel.setPreferredSize(new Dimension(100,100));
myPanel.setBackground(Color.BLACK);
FixedPanel.add(myPanel);
Frame.add(FixedPanel);
Frame.setVisible(true);

You can do this. I had to make a chess game, and I wanted the chess piece piece to always go in the center of a cell which was a JlayeredPane:
private void formMouseReleased(java.awt.event.MouseEvent evt) {
// TODO add your handling code here:
if (jl != null)
{
jl.setLocation(evt.getX()+10, evt.getY()+10);
Component com = findComponentAt(evt.getPoint());
if (com instanceof JPanel)
{
// System.out.println("Yes, it's a jpanel");
((JPanel)com).add(jl);
((JPanel)com).validate();
}
}
}

Its Just Having
jPanel.setBounds(x, y, 1046, 503);
Where x is space for right side and y is space for left side.
you have to calculate the space from both side according to screen height and width

use
panel.setMaximumSize(new Dimension(200,200));
panel.setResizable(false)
instead?