Develop Reference

jsplitpane and paintcomponent conflicting with each other

I'm having issues with my code regarding the fact that when I instantiate my City class as an object and add it to the right side of my JSplitPane (or even the left), the circle that is supposed to be drawn is not showing up. My cities class uses paintComponent and should draw a circle just by calling the constructor. I have also tried putting the repaint in its own drawIt() method but the result is still the same. The buttons and spinner show up on the left side of the divider, but the circle I am trying to draw does not show up at all.
Here is my City class.
import javax.swing.*;
import java.awt.*;
public class City extends JPanel{
int xPos, yPos;
City(int x, int y){
xPos = x;
yPos = y;
repaint();
}
public void paintComponent(Graphics g){
super.paintComponent(g);
g.setColor(Color.BLACK);
g.fillOval(xPos, yPos, 10, 10);
}
}
And here is my main.
Here I try to instantiate my city and add it to the right side of the JSplitPane (under Add Components) and that is where I am having issues with, as the black circle will not be drawn on the JSplitPane.
import java.awt.*;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.JSplitPane;
import javax.swing.SpinnerNumberModel;
import javax.swing.SwingUtilities;
public class TSP{
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TSP();
}
});
}
TSP(){
JLabel instructions = new JLabel("Enter the number of cities: ");
instructions.setBounds(30, 150, 300, 40);
SpinnerNumberModel numMod = new SpinnerNumberModel(2, 2, 10, 1);
JSpinner numOfCities = new JSpinner(numMod);
numOfCities.setBounds(185, 150, 80, 40);
JButton start = new JButton("Start Simulation");
start.setBounds(50, 400, 200, 40);
JFrame frame = new JFrame("Travelling Salesperson");
JSplitPane sp = new JSplitPane(JSplitPane.HORIZONTAL_SPLIT);
JPanel lp = new JPanel(null);
JPanel rp = new JPanel(null);
sp.setDividerLocation(300);
sp.setLeftComponent(lp);
sp.setRightComponent(rp);
sp.setEnabled(false);
frame.setDefaultCloseOperation(3);
frame.setSize(1100,600);
frame.setResizable(false);
////////////////Add Components//////////////////////////
lp.add(instructions);
lp.add(numOfCities);
lp.add(start);
City test = new City(301, 301);
rp.add(test);
frame.add(sp);
////////////////////////////////////////////////////////
frame.setVisible(true);
}
}
I feel like the circle is being drawn under the JSplitPane as if I add my cities object (test) to my frame instead of the JSplitPane(frame.add(test) instead of rp.add(test) under the Add Components section) the black circle will appear in the desired spot but the JSplitPane along with the buttons and spinners will disappear so I feel as if they are conflicting. Is there any fix to this or is there another way altogether to make the circle appear on the right side while the other components are on the left side.
I do not know why it is not drawing the circle on the JSplitPane, but any sort of help would be appreciated. Thanks!
Sorry if anything is unclear or there is any ambiguity in my code, or if I need to post more information as I am quite new to posting here. Let me know if there is anything else I need to add or if there are any questions regarding what I am asking!
EDIT:
It seems there is something blocking where I draw the circle, like another JPanel. Here is an image below. As you can see part of the circle looks as if it is being covered. The small box I drew is the only area that the dot is visible from (everywhere else the circle is covered up by white). Also, the coordinates for the circle in the image below is at (3, 0), i.e City test = new City(3, 0);
I am not quite sure why this is happening though.
the invisible JPanel?

Now that I've seen what you're trying to do, I can provide a more proper answer.
You have a control panel on the left and a drawing panel on the right. Usually, you don't use a JSplitPane to separate the panels. To create your layout, you would add the control panel to the LINE_START of the JFrame BorderLayout and the drawing panel to the CENTER.
The reason for this is that you don't want to constantly recalculate the size of the drawing panel.
So let me show you one way to get a solid start. Here's the GUI I created.
Here are the things I did.
All Swing GUI applications must start with a call to the SwingUtilities invokeLater method. This method ensures that Swing components are created and executed on the Event Dispatch Thread.
I separated the creation of the JFrame, the control panel, and the drawing panel. That way, I could focus on one part of the GUI at a time.
The JFrame methods must be called in a certain order. This is the order that I use for most of my Swing applications.
The JFrame is not sized. It is packed. The Swing layout managers will calculate the size of the components and the JPanels.
I used a FlowLayout and a GridBagLayout to create the control panel. Yes, this looks more complicated than absolute positioning, but in the long run, layout managers allow the GUI to be more flexible.
I used the setPreferredSize method in the drawing panel to set the preferred size of the drawing panel. Because I know the drawing panel size, I can put the first city in the center of the drawing panel.
And here's the code. You don't have to code exactly like this, but this code should give you a good basis to start your project. Take a look at the model / view / controller pattern and see how to further separate your code into smaller pieces that allow you to focus on one part of your application at a time.
I put all the classes in one file to make it easier to paste. You should separate these classes into separate files.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Insets;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSpinner;
import javax.swing.SpinnerNumberModel;
import javax.swing.SwingUtilities;
public class CitySimulation implements Runnable {
public static void main(String[] args) {
SwingUtilities.invokeLater(new CitySimulation());
}
private ControlPanel controlPanel;
private DrawingPanel drawingPanel;
private JFrame frame;
#Override
public void run() {
frame = new JFrame("Traveling Salesperson");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
controlPanel = new ControlPanel();
frame.add(controlPanel.getPanel(), BorderLayout.LINE_START);
drawingPanel = new DrawingPanel();
frame.add(drawingPanel, BorderLayout.CENTER);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public class ControlPanel {
private JPanel panel;
public ControlPanel() {
panel = new JPanel(new FlowLayout());
JPanel mainPanel = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.anchor = GridBagConstraints.LINE_START;
gbc.fill = GridBagConstraints.HORIZONTAL;
gbc.gridx = 0;
gbc.gridy = 0;
gbc.insets = new Insets(10, 10, 10, 10);
JLabel instructions = new JLabel("Enter the number " +
"of cities:");
mainPanel.add(instructions, gbc);
gbc.gridx++;
gbc.insets = new Insets(10, 0, 10, 10);
SpinnerNumberModel numMod =
new SpinnerNumberModel(2, 2, 10, 1);
JSpinner numOfCities = new JSpinner(numMod);
mainPanel.add(numOfCities, gbc);
gbc.anchor = GridBagConstraints.CENTER;
gbc.gridx = 0;
gbc.gridy++;
gbc.gridwidth = 2;
gbc.insets = new Insets(10, 10, 10, 10);
JButton start = new JButton("Start Simulation");
mainPanel.add(start, gbc);
panel.add(mainPanel);
}
public JPanel getPanel() {
return panel;
}
}
public class DrawingPanel extends JPanel {
private static final long serialVersionUID = 1L;
public DrawingPanel() {
this.setBackground(Color.WHITE);
this.setPreferredSize(new Dimension(400, 400));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.BLACK);
g.fillOval(195, 195, 10, 10);
}
}
}

Java - My action event doesn't work

I'm learning Java and Swing, but my JButton doesn't work.
import javax.swing.JFrame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class Programma {
public static void main(String[] args) {
// TODO Auto-generated method stub
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch (Exception e){
e.printStackTrace();
}
JFrame frame = new JFrame("DIG");
JPanel panel = new JPanel();
JButton button = new JButton("Click Me");
frame.setSize(400, 400);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
button.setBounds(100, 100, 130, 35);
panel.add(button);
frame.add(panel);
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
// TODO Auto-generated method stub
JLabel label = new JLabel("Hello World");
label.setVisible(true);
panel.add(label);
}
});
}
}
The frame and button are visible, nut when I click it, the label doesn't appear. How can I fix this?
Do I write this before the other component like JPanel, JButton, etc., or do I write this at the end of code:
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
What is the difference ?
By the way, button.setBounds(100, 100, 130, 35) doesn't work, either.

I see some issues in your code:
button.setBounds(100, 100, 130, 35); that line will be ignored and you shouldn't be manually be determining the position of the components. See Null layout is evil and Why is it frowned upon to use a null layout in swing? altough you're not using null layout, there is explained why you shouldn't be manually determining the positions of the components.
You're running everything in your program in the main method, that will be hard to maintain later.
You're calling frame.setVisible(true) before you've added all your elements to it, that will cause you random issues.
You're not running your program on the Event Dispatch Thread (EDT), you can solve this by starting your program with the following code, which places it in the EDT. It's recommended as Swing is not thread safe.
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
//Your constructor here
}
});
}
You're setting the size of the JFrame with setSize(...), instead call frame.pack() and override the getPreferredSize() method of the JPanel.
After all the above has been said, you need to call revalidate() and repaint() on your ActionListener so your program paints its new state.
This program follows all the above recommendations and produces the following outputs (before clicking and after clicking the button 3 times), I on purpose to not make the images so large, made the GUI shorter (200 x 200 instead of 400 x 400)
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Programma {
private JFrame frame;
private JPanel panel;
private JButton button;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Programma().createAndShowGui();
}
});
}
public void createAndShowGui() {
frame = new JFrame("DIG");
panel = new JPanel() {
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
};
button = new JButton("Click Me");
panel.add(button);
button.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JLabel label = new JLabel("Hello World");
panel.add(label);
panel.revalidate();
panel.repaint();
}
});
frame.add(panel);
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Do i write this before the other componente like JPanel,JButton... or do i write this at the end of code ?
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
What is the difference ?
Altough I answered this on the recommendations, the difference is that if you call setVisible before adding all your elements to the frame, then you'll find yourself with some random issues where the components are not all visible until you pass your mouse over them (or where they should be). frame.pack() and setVisible should be the last ones to be called in your program, and frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); can be at the start or the end, it doesn't affects, but I prefer to have it at the end too.
button.setBounds(100, 100, 130, 35); doesn't work too.
Well, that's because of you're using a layout manager (and that's the right way to do your GUIs) instead of a null-layout (which you shouldn't be using anyway) (See point #1).
Edit
What is the difference between frame.setSize(); and frame.setpack() ?
If you read the docs for pack():
Causes this Window to be sized to fit the preferred size and layouts of its subcomponents. The resulting width and height of the window are automatically enlarged if either of dimensions is less than the minimum size as specified by the previous call to the setMinimumSize method.
So, it will calculate the minimum size for your JFrame where all the elements are visible and in their preferred size while setSize will only set the window size, but if you place a JScrollBar inside it for example this will reduce the window size, because of that, that's why you should override the getPreferredSize(...) method of your container, so it will calculate its preferred size including the width of the JScrollBar or some other elements that could modify its size. See Should I avoid the use of setPreferred|Maximum|MinimumSize in Swing? (the general consensus says yes)

When you add components dynamically to panel, you need to repain it.
Do this
panel.revalidate();
after
panel.add(label);

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

Placing a JLabel at a specific x,y coordinate on a JPanel

I'm trying to place a series of JLabels at specific X and Y coordinates on a JPanel (and set its height and width, too). No matter what I do, each label winds up immediately to the right of the previous label and has the exact same size as all of the others.
Right now, my Jpanel is in a Grid Layout. I've tried Absolute Layout (illegal argument exception results), Free Design (no labels appear), Flow Layout (everything just gets squeezed to the center), and a few others.
Not sure what I need to do to make this work. Can anyone help? Thanks!
JLabel lbl1 = new JLabel("label 1");
JLabel lbl2 = new JLabel("label 2");
JLabel lbl3 = new JLabel("label 3");
JLabel lbl4 = new JLabel("label 4");
JLabel lbl5 = new JLabel("label 5");
myPanel.add(lbl1);
myPanel.add(lbl2);
myPanel.add(lbl3);
myPanel.add(lbl4);
myPanel.add(lbl5);
lbl1.setLocation(27, 20);
lbl2.setLocation(123, 20);
lbl3.setLocation(273, 20);
lbl4.setLocation(363, 20);
lbl5.setLocation(453, 20);
lbl1.setSize(86, 14);
lbl2.setSize(140, 14);
lbl3.setSize(80, 14);
lbl4.setSize(80, 14);
lbl5.setSize(130, 14);

You have to set your container's Layout to null:
myPanel.setLayout(null);
However is a good advise also to take a look at the Matisse Layout Manager, I guess it is called GroupLayout now. The main problem with absolute positioning is what happens when the window changes its size.

Set the container's layout manager to null by calling setLayout(null).
Call the Component class's setbounds method for each of the container's children.
Call the Component class's repaint method.
Note:
Creating containers with absolutely positioned containers can cause problems if the window containing the container is resized.
Refer this link:
http://docs.oracle.com/javase/tutorial/uiswing/layout/none.html

Layout managers are used to automatically determine the layout of components in a container. If you want to put components at specific coordinate locations, then you should not use a layout manager at all.
myPanel = new JPanel(null);
or
myPanel.setLayout(null);

My advise is to use an IDE like NetBeans with its GUI editor. To inspect the code and because there are many ways:
Setting the layout manager, or for absolute positioning doing a myPanel.setLayout(null), has several influences.
In general, assuming you do your calls in the constructor of a JFrame, you can call pack() to start the layouting.
Then, every layout manager uses its own implementation of add(Component) or add(Component, Constraint). BorderLayout's usage is with add(label, BorderLayout.CENTER) and so on.

// Best solution!!
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Main {
public static void main(String args[]) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = (JPanel) frame.getContentPane();
panel.setLayout(null);
JLabel label = new JLabel("aaa");
panel.add(label);
Dimension size = label.getPreferredSize();
label.setBounds(100, 100, size.width, size.height);
frame.setSize(300, 200);
frame.setVisible(true);
}
}

You can use your own method that calling by setSize, setLocation values for directly....! `
As well i show you how to use JProgress Bar
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class installComp{
void install(Component comp, int w, int h, int x, int y){
comp.setSize(w,h);
comp.setLocation(x,y);
}
}
class MyFrame extends JFrame{
int cur_val = 0;
JButton btn = new JButton("Mouse Over");
JProgressBar progress = new JProgressBar(0,100);
MyFrame (){
installComp comp=new installComp();
comp.install(btn,150,30,175,20);
comp.install(progress,400,20,50,70);
btn.addMouseListener(new MouseAdapter(){
public void mouseEntered(MouseEvent evt){
cur_val+=2;
progress.setValue(cur_val);
progress.setStringPainted(true);
progress.setString(null);
}
});
add(btn);
add(progress);
setLayout(null);
setSize(500,150);
setResizable(false);
setDefaultCloseOperation(3);
setLocationRelativeTo(null);
setVisible(true);
}
}
class Demo{
public static void main(String args[]){
MyFrame f1=new MyFrame();
}
}

JLabel doesnt appear

Im having this problem where my Label2 which is assigned to be a text doesn't appear on the Jframe, even though I added it. Im assuming the other Labels which I set as images are overlaping it? If that is the problem how would I go upon fixing it?
import java.awt.Dimension;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingUtilities;
public class Generator extends JFrame {
private static final long serialVersionUID = 1L;
/**
* Launch the application.
*/
public static void main(final String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
try {
final Generator frame = new Generator();
frame.setVisible(true);
} catch (final Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the frame.
*/
public Generator() {
/*
* #Images/Text
*/
final ImageIcon icon = new ImageIcon("data/hover_a.png");
final JLabel label = new JLabel(icon);
final ImageIcon icon1 = new ImageIcon("data/background.png");
final JLabel label1 = new JLabel(icon1);
final ImageIcon img = new ImageIcon("data/icon.png");
final JLabel label2 = new JLabel("Test Text");
/*
* #Image/Text Bounds
*/
label.setBounds(24, 266, 240, 40);
label1.setBounds(0, 0, 289, 330);
label2.setBounds(0, 0, 80, 15);
/*
* #Image Hovers
*/
label.addMouseListener(new MouseAdapter() {
#Override
public void mouseEntered(final MouseEvent evt) {
label.setIcon(new ImageIcon("data/hover_b.png"));
}
#Override
public void mouseExited(final MouseEvent evt) {
label.setIcon(new ImageIcon("data/hover_a.png"));
}
});
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setPreferredSize(new Dimension(295, 358));
setTitle("test");
getContentPane().setLayout(null);
setResizable(false);
setVisible(true);
setIconImage(img.getImage());
getContentPane().add(label);
getContentPane().add(label1);
getContentPane().add(label2);
pack();
}
}

You're calling setVisible(true) before adding all your components. Don't do this. The orde is:
add your components
call pack()
call setVisible(true)
if later you make changes then call revalidate() on the container, then repaint()

From reading your code, it appears that you are trying to layer images on top of each other. This would be much better achieved through the use of customer panels with custom painting
Have a look at the Performing Custom Painting lesson & 2D Graphics Trail
Without know precisely what you want to achieve, I would create a background panel that paints the background and then I would use a layout manager to layout the two other icons (personally, I used a GridBagLayout, but it might be a little over kill for you needs)
I would also familiarise your self with the painting order of components