Develop Reference

How to display a JLabel on top of another JLabel, with specified coordinate?

I'm working on a GUI for a Tic Tac Toe project, in which I want to get an image (the player's move) to show up when clicking the corresponding area. However, I can't figure out how to display a JLabel (the move) on top of another JLabel (the background).
I have searched and tried to use layeredpanes, but it just fails to show the entire frame when I run it. I am new to GUI, so I am not quite sure if I implemented it correctly.
layer = new JLayeredPane();
//set up the board as background
String path = "sampleUrl";
URL url = new URL(path);
BufferedImage image = ImageIO.read(url);
bg4 = new JLabel(new ImageIcon(image));
layer.add(bg4, new Integer(-1));
frame.add(layer);
frame.pack();
frame.addMouseListener(new MouseListener4());
String xPath = "sampleUrl";
URL xUrl = new URL(xPath);
BufferedImage x = ImageIO.read(xUrl);
icon = new JLabel(new ImageIcon(x));
layer.add(icon);
It just shows up a window with minimum width and height, without displaying the background. Is there something wrong with this code, or any other ways for me to put a JLabel on top of another JLabel?

You can add one label object into another, as JLabel is a container. Try something like this.
JLabel parentLabel = new JLabel("Parent");
JLabel childLabel = new JLabel("Child");
parentLabel.add(childLabel );

I highly recommend you to read about javafx if you are new in GUI.you can merge nodes in any way you need.you can put labels on each other using stackpane,and display them top and down of each other using gridpane very easily.
more information on:
https://docs.oracle.com/javafx/2/

Display images dynamically in a ScrollPane

I want to add multiple images in a ScrollPane when clicking a button. Now when I click the button a new rectangle is created and fitted with a new image.
The problem is the scrollbar is not displaying when a new image is added.
Here is the code:
#FXML
public void handleButtonPause(){
Rectangle r = new Rectangle();
if(counterIm==0){
//Ap1.setMinSize(Sp1.getWidth(), Sp1.getHeight() - 10);
r.setY(Sp1.getHeight() *((double)1/36));
r.setWidth(Sp1.getWidth()*0.75);
rectWidth=r.getWidth();
r.setHeight(Sp1.getHeight()/6);
rectHeight=r.getHeight();
}
else {
r.setY(Sp1.getHeight()*((7*counterIm+1)/36));
r.setWidth(rectWidth);
r.setHeight(rectHeight);
}
r.setX(Sp1.getWidth() / 10);
r.setArcWidth(20);
r.setArcHeight(20);
Ap1.getChildren().add(r);
Image image = new Image(new File("C:\\Users\\Manuel\\Desktop\\error.png").toURI().toString());
r.setFill(new ImagePattern(image));
Sp1.setVvalue(1);
counterIm=counterIm+1;

I don't know how your composition looks like.
A good approach could be to put the images into a VBox and put the VBox into the ScrollPane.
And check if you have set the VBar Policy of your SrollPane:
srollbar.setVbarPolicy(ScrollBarPolicy.AS_NEEDED);
You can also set the maximal height of the VBox to double maximum to make it sure it will always grow vertically:
vbox.setMaxHeight(Double.MAX_VALUE);

jpanel cannot make gridlayout with 7 rows and 2 cols

i want to ask if anything goes wrong with my code. i've set my frame with borderlayout . and on the center part, i want to use gridlayout with 7rows and 2 cols inside them.
paneltengah= new JPanel();
paneltengah.setLayout(new GridLayout(7,2));
labelname = new JLabel(lbl_name,SwingConstants.LEFT);
labelusername = new JLabel(lbl_username,SwingConstants.LEFT);
labelpassword = new JLabel(lbl_password,SwingConstants.LEFT);
labelgender = new JLabel(lbl_gender,SwingConstants.LEFT);
labelemail = new JLabel(lbl_email,SwingConstants.LEFT);
labelhobby = new JLabel(lbl_hobby,SwingConstants.LEFT);
labelrole = new JLabel(lbl_role,SwingConstants.LEFT);
textname = new JTextField(20);
textusername = new JTextField(20);
textpassword = new JPasswordField(20);
textemail = new JTextField(20);
comboboxhobby = new JComboBox();
comboboxrole = new JComboBox();
radiobuttonmale = new JRadioButton("Male");
radiobuttonfemale = new JRadioButton("Female");
ButtonGroup btngroup = new ButtonGroup();
btngroup.add(radiobuttonmale);
btngroup.add(radiobuttonfemale);
paneltengah.add(labelname);
paneltengah.add(labelusername);
paneltengah.add(labelpassword);
paneltengah.add(labelgender);
paneltengah.add(labelemail);
paneltengah.add(labelrole);
paneltengah.add(labelhobby);
//// paneltengah.add(textname); when i open this, the layout become awkward
//// paneltengah.add(textusername);
//// paneltengah.add(textpassword);
//// paneltengah.add(radiobuttonmale);
//// paneltengah.add(radiobuttonfemale);
//// paneltengah.add(comboboxhobby);
//// paneltengah.add(comboboxrole);
pane.add(paneltengah, BorderLayout.CENTER);
the following pictures is shown without opening the comment
the following picture is shown with uncomment
what is wrong with my code ?

First of all, a GridLayout sizes all components evenly in its associated Container, which explains why your labels and fields are all the same size. For example, if you had a JTextArea 200 columns × 20 lines in your JPanel, then even the tiniest label would occupy that huge a space as well!
Next, according to the GridLayout Javadoc, when a GridLayout instance is constructed with two non-zero arguments, the number of rows gets fixed and the number of columns is adjusted according to the number of components put into the parent Container.
What I suggest is using a BorderLayout to set up your main form layout. Put your title at NORTH and keep the CENTER for your labels and fields (your current JPanel).
For your labels and fields, the simplest solution might be using a GridLayout(0, 2) (fixed number of columns). But all your components will still be equally sized.
If you need more control over the size of your components (e.g., fields wider than labels), then I suggest using another layout manager such as GridBagLayout. I know it's more complex to manage but using a GridBagLayout formatting preview utility should help. Such a program may be named something like GridBagLab (I know David Geary's book Graphic Java volume 2 — Swing features one on its companion CD).
There is also a GridBagLayout tutorial at https://www.youtube.com/watch?v=Ts5fsHXIuvI.

How can you add several elements to a JScrollPane

So I am trying to add more than one element to a JScrollPane element but so far I haven't been able to pull it of.
I can make it so that the first element shows up ,which in my case is a picture. But after adding in an extra panel to the JScrollPane ,the first element disappears and even the second element ,the new panel , doesnt show on my JScrollPane.
JFrame scherm = new JFrame("t?");
scherm.setVisible(true);
scherm.setSize(300, 300);
scherm.setLocationRelativeTo(null);
scherm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//
String path = "C:\\Users\\Bernard\\Documents\\Paradox Interactive\\Crusader Kings II\\mod\\viking\\map\\provinces.bmp";
Image image = ImageIO.read(new File(path));
ImageIcon icon = new ImageIcon(image);
JLabel label = new JLabel(icon);
JScrollPane scroll = new JScrollPane(label);
JPanel paneel2= new JPanel();
paneel2.setSize(new Dimension(400,400));
scroll.getViewport().add(paneel2,null);
scherm.add(scroll);
Thank you for your time!

By doing this:
scroll.getViewport().add(paneel2,null);
You're trying to add a component to the scroll pane's JViewPort shown in the picture below:
This makes no sense. As stated in How to Use Scroll Panes trial:
A
JScrollPane
provides a scrollable view of a component.
This single component is the view port's view. So if you want to have more than a single component in your scroll pane you must to wrap all those components in a lightweight component such as JPanel and set this one as the scroll pane's view port view:
JPanel content = new JPanel();
content.add(label);
content.add(paneel2);
scroll.setViewportView(content);

How to create widget like google maps in GWT?

I need to create widget, similar to google maps one.
In it's simplest form, the map of all planet is divided into image tiles. While user scrolls the widget into different directions, new empty cells appeared and widget requests these tiles from the server and put it into the widget.
How it can be implemented in GWT?
I found no way to set absolute position dynamically in ScrollPanel. I found no way to draw something lefter than left or upper then top in AbsolutePanel. How to combine panels correctly?
Thanks.
UPDATE 1
Here is one of the examples. In this example labels do not show, because the size of containing absolute panel is zero by height (looked in firebug). I can't just set it's size because this won't help for label at -100,-100.
public void onModuleLoad() {
Label label_minus100_minus100 = new Label("(-100,-100)");
Label label_0_0 = new Label("(0,0)");
Label label_100_100 = new Label("(100,100)");
AbsolutePanel absolutePanel = new AbsolutePanel();
absolutePanel.setStyleName("absolutePanel");
absolutePanel.add(label_0_0, 0, 0);
absolutePanel.add(label_minus100_minus100, -100, -100);
absolutePanel.add(label_100_100, 100, 100);
DOM.setStyleAttribute(absolutePanel.getElement(), "overflow", "visible");
ScrollPanel scrollPanel = new ScrollPanel();
scrollPanel.add(absolutePanel);
scrollPanel.setStyleName("scrollPanel");
RootPanel rootPanel = RootPanel.get();
rootPanel.add(scrollPanel);
}