I intend to take the elements of an integer list and add it to a label and print them in downward fashion one after another. I wrote the following code for it.
public static JFrame ListDraw(JFrame frame , ArrayList<Integer> e)
{
for(int i= 0;i<e.size();i++)
{
JLabel j = new JLabel(e.get(i).toString(),JLabel.CENTER);
frame.add(j);
}
return frame;
}
But it just prints the last array element in the label. What am I doing wrong here?
---------------------(update)
This is just a query that I have regarding the same thing. Therefore I am going to ask it here only. Is there any way to print the label items in a stack as in vertical alignment. Right now I get all the values printed in the horizontal fashion.
I guess you need to set layout for your frame, f.ex: frame.setLayout(new FlowLayout());.
Your frame isn't adapting to the new group of elements- the LayoutManager isn't getting a chance to resize the window. At the end of your function, add frame.pack().
You should use setBounds() to define the size of your frame and give it a LayoutManager of your choice.
Related
I'm developing a Java GUI and I need:
A label in first row(only one label).
Starting 2nd row need to add say 100 buttons which extends to multiple lines(width shouldn't go beyond the visible screen)
In a new line one more Label
From next line say 100 buttons which extends to multiple lines(width shouldn't go beyond the visible screen)...
[OPTIONAL] If the components exceeds JFrame height then need a scroll facility to the main window (only vertical)
I have a strange results with flow layout, sometimes it stick to visible width, sometimes it sets even 500 buttons in a single row.
I have tried every layout and also multipanes. Still no luck.
Please guide.. just need an idea, No need of code
Updated with code: Sorry guys, that was my first question to stackoverflow
Thanks for prompt response
Infact i tried many, here is a simple one.
setLayout(new FlowLayout());
setTitle("JAVA GUI");
setSize(500,500);
setVisible(true);
add(new JLabel("row 1"));
JPanel panel1 = new JPanel(new FlowLayout());
for(int i=0;i<200;i++){
panel1.add(new JButton("b"+i));
}
add(panel1);
Here the panel1 is appearing in a sigle row which goes beyond the visible part of the screen.
I think this can be solved by setting maximumsize to Jframe, but no idea how to set its size to FULL SCREEN.
You can try MigLayout.
http://www.miglayout.com/
Also this question is not really a question for stack overflow. A good way to ask your question would be to post your code and tell us what is wrong with it and what it is supposed to do.
While this is not the norm for 'good' stackOverflow questions, I don't have any problem with it myself. Some people cannot deal with anything except code. I would suggest that, if you're going to post code, that you take the trouble to post code that will compile, run, and demonstrate your situation. It really helps those of us out here understand what you're seeing and what you're trying to do.
You talk about "rows"; be aware that rows and columns are terms used with things like GridLayout and GridBagLayout, but I don't think they're appropriate for what you describe.
In your description, you don't say what you want scrolled. It would appear you want the entirety of the UI scrolled, I'll assume that for now.
I would try a JPanel with BoxLayout, oriented vertically, for the overall main UI. You will put some things into that:
The first JPanel.
Another JPanel, set with FlowLayout, holding the first bunch of buttons.
Another JPanel with the next JLabel
And a fourth JPanel, set with FlowLayout, holding the second bunch of buttons.
Now, I would put the top-level panel into a JScrollPane, and then put that into the CENTER section of a Frame (with its default BorderLayout), and see what happens. To tell the truth, I'm not sure, but these are the things I would start with.
I cannot tell, without running code, why you get odd behavior sometimes.
As said in a previous comment, using a ContentPane is the way to go. Here is a working example of what you want:
public class Test {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setTitle("JAVA GUI");
JPanel panel1 = new JPanel();
panel1.setLayout(new BoxLayout(panel1, BoxLayout.Y_AXIS));
int nbLines = 10;
for (int i = 0; i < nbLines; i++) {
JPanel linePanel = new JPanel(new FlowLayout());
linePanel.add(new JLabel("row " + i));
for(int j = 0; j < 50; j++) {
linePanel.add(new JButton("b" + j));
}
panel1.add(linePanel);
}
frame.setContentPane(panel1);
//frame.setSize(500, 500);
frame.setExtendedState(frame.getExtendedState() | JFrame.MAXIMIZED_BOTH);
frame.pack();
frame.setVisible(true);
}
}
And here is what I get:
If you want to have left-aligned buttons you can use:
JPanel linePanel = new JPanel(new FlowLayout(FlowLayout.LEFT));
I'm having more "I'm hopeless at programming" problems.
I have a piece of code which uses StringBuilder to display elements of an array in a text panel of a GUI when the program starts. Here's the StringBuilder code:
// memory tab
StringBuilder mList = new StringBuilder();
memLocList = new Memory[MEM_LOCATIONS];
mem = new Memory();
for (int i = 0; i < memLocList.length; i++) {
memLocList[i] = mem;
memLocList[i].setOpCode(00);
mList.append(String.format("%10s %04x %10s %6s", "Address: ", i,
"Value: ", memLocList[i].getOpCode()));
mList.append("\n");
}
JComponent memTab = makeTextPanel(mList.toString());
tabs.addTab("Memory", new JScrollPane(memTab));
}
protected JComponent makeTextPanel(String t) {
text = t;
JPanel panel = new JPanel(false);
JTextPane filler = new JTextPane();
filler.setFont(new Font("Courier", Font.PLAIN, 14));
filler.setText(text);
filler.setAlignmentX(LEFT_ALIGNMENT);
panel.setLayout(new GridLayout(1, 1));
panel.add(filler);
return panel;
}
The GUI also has a text entry panel where a String of hex values can be entered.
On clicking a button, the user is prompted for another value, which corresponds to the position in the array where the first hex value should be inserted.
Once these values have been entered, I'd like the display to be updated / refreshed to reflect this but am unsure of how to go about it.
I found this question here, which is similar but I'm not sure if implementing Observer/Observable pattern is the right way to proceed, and even if it is, how I'd go about it:
Best Way to Constantly Update GUI Elements
My initial approach was to add an "updateDisplay()" method, which I could call after processing the button click and re-call the makeTextPanel method:
public void updateDisplay() {
makeTextPanel(text);
}
I thought this might refresh it but it has no effect of the display.
Any help appreciated.
You hold your array in a model class, and you allow other classes to "listen" to this by giving this class a SwingPropertyChangeSupport object as well as an addPropertyChangeListener(...) method. Then give the array a setXXX(...) method, and in that method fire the SwingPropertyChangeSupport object after updating the array. There are examples of just this sort of thing on this site, some written by me.
For example: here, here, here, ...
By the way, I'm not surprised that your call to makeTextPanel(text) doesn't work. It creates a JPanel, but you don't appear to do anything with the JPanel that is returned from the method. But nor should you. I don't think that creating new JPanels is the solution you want, but rather updating the Strings displayed by a component of some sort such as a JList or JTextArea using the listener framework that I've described above.
If any of this is confusing, please ask for clarification.
I've got a Jlist inside a JScrollPane and I've set a prototype value so that it doesn't have to calculate the width for big lists, but just uses this default width.
Now, the problem is that the Jlist is for some reason replacing the end of an element with dots (...) so that a horizontal scrollbar will never be shown.
How do I disable with "wrapping"? So that long elements are not being replaced with dots if they are wider than the Jlist's width?
I've reproduced the issue in a small example application. Please run it if you don't understand what I mean:
import javax.swing.*;
import java.awt.*;
public class Test
{
//window
private static final int windowWidth = 450;
private static final int windowHeight = 500;
//components
private JFrame frame;
private JList classesList;
private DefaultListModel classesListModel;
public Test()
{
load();
}
private void load()
{
//create window
frame = new JFrame("Test");
frame.setSize(windowWidth, windowHeight);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setUndecorated(true);
frame.getRootPane().setWindowDecorationStyle(JRootPane.PLAIN_DIALOG);
//classes list
classesListModel = new DefaultListModel();
classesList = new JList(classesListModel);
classesList.setPrototypeCellValue("prototype value");
classesList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
classesList.setVisibleRowCount(20);
JScrollPane scrollClasses = new JScrollPane(classesList, JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
for (int i = 0; i < 200; i++)
{
classesListModel.addElement("this is a long string, does not fit in width");
}
//panel
JPanel drawingArea = new JPanel();
drawingArea.setBackground(Color.white);
drawingArea.add(scrollClasses);
frame.add(drawingArea);
//set visible
frame.setVisible(true);
}
}
Even if you force horizontal scrollbar, you still won't be able to scroll because the element is actually not wider than the width because of the dot (...) wrapping.
Thanks in advance.
Scrollbars appear automatically when the preferred size of the component added to the scrollpane is greater than the size of the scrollpane.
By using the setPrototypeCellValue(...) method you are affecting the way the list calculates its preferred size, which means you are responsible for providing the proper value that ensures the strings will not be truncated.
So the simple solution is not not use that method, but in addition you will need to set the preferred size of the scrollpane to be whatever you want. Then the horizontal scrollbars will appear if required.
My answer to that question is that first find the longest element in the list then use
setPrototype method on that elements
When you call classesList.setPrototypeCellValue("prototype value") you are telling the JList classesList to limit its maximum width to the length of the string "prototype value". (See javadocs)
Then later on when you populate the list with the strings "this is a long string, does not fit in width", no wonder it does not fit in the width! Because the width of the prototype you gave it is smaller than the width of the string you are filling the list with.
The JScrollPane will automatically show the scrollbars and you usually don't need to adjust their behavior. The JList will also automatically adjust its width to try and show the maximum width item in the list. The problem occurs when you tell the JList to fix its width by calling the setPrototypeCellValue().
If you comment out
classesList.setPrototypeCellValue("prototype value");
or replace it with
classesList.setPrototypeCellValue("this is a long string, does not fit in width");
then it will function as you expected it to.
I am trying to implement a JScrollPane with a JTextArea. The JTextArea is being appended to, and I want the JScrollPane to keep scrolling down as more text is added. How can this be achieved?
For (what I think is) a simpler answer check out: Text Area Scrolling.
Prior to JDK5, you would have to manually change the caret's position after each append. You can now give this behaviour as a default like this :
JTextArea textArea = new JTextArea();
DefaultCaret caret = (DefaultCaret)textArea.getCaret();
caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);
The advantage of this is that you don't need to use this snippet more than once in your code!
I found the answer here:
JScrollPane and JList auto scroll
scrollPane.getVerticalScrollBar().addAdjustmentListener(new AdjustmentListener() {
public void adjustmentValueChanged(AdjustmentEvent e) {
e.getAdjustable().setValue(e.getAdjustable().getMaximum());
}
});
If you are constantly writing data to it you could use:
textArea.setCaretPosition(textArea.getDocument().getLength());
just after you add the new data.
This would automatically scroll all the way down the JScorllPane.
Here is the solution.
JTextArea textArea = new JTextArea();
DefaultCaret caret = (DefaultCaret)textArea.getCaret();
caret.setUpdatePolicy(DefaultCaret.ALWAYS_UPDATE);`
The accepted solution works good, but only when the text area is editable, i.e. without jTextArea.setEditable(false) . The solution suggested by Krigath is more general, but has the problem as asked here JScrollPane and JList auto scroll. Using answers from that question you can get general solution, e.g.:
JScrollPane scrollPane = new JScrollPane(jTextArea);
verticalScrollBarMaximumValue = scrollPane.getVerticalScrollBar().getMaximum();
scrollPane.getVerticalScrollBar().addAdjustmentListener(
e -> {
if ((verticalScrollBarMaximumValue - e.getAdjustable().getMaximum()) == 0)
return;
e.getAdjustable().setValue(e.getAdjustable().getMaximum());
verticalScrollBarMaximumValue = scrollPane.getVerticalScrollBar().getMaximum();
});
The Pane then is scrolled down only when vertical scroll bar is expanding, in response to appended lines of text.
I admit that that a method to filter events without extra variables could be found, and would appreciate if somebody post it.
A work around is possible: you can declare that listener as a class then instantiate it on the event where it is needed. After which you can remove the class after forcing a repaint of the screen. Works like a charm.
I was look at the answers and found that #user9999 answer is a good solution for those who want the scrollbar continuously scroll. I edited the code, got rid of the variable. It make the scrolling stop - when the user is scrolling manually. If the user scrolls to the end of the textarea or scrollarea, the auto scrolling continues.
(also as #user9999 suggested i removed the variable and added the jScrollPane1.getHeight() as the measure value to stop scrolling if the current scrollbar value is lower than max)
Here is the workaround:
jScrollPane1.getVerticalScrollBar().addAdjustmentListener(
e -> {
if ((e.getAdjustable().getValue() - e.getAdjustable().getMaximum()) > -jScrollPane1.getHeight() - 20){
e.getAdjustable().setValue(e.getAdjustable().getMaximum());
}
});
Edit:
Added -20 to the -jScrollPane1.getHeight() - 20 as it is sometimes doesnt scroll without it, i guess the -20 can be changed depends on the font size of the TextArea.
Be careful if you're about to use auto scroll within a multithreaded program.
Like for example if somewhere is a method like
public void addNewLine(String s){
textPane.setText(textPane.getText()+"\n"+s);
if(autoscrollCheckBox.isSelected()){
this.revalidate();
JScrollBar vertical = scrollPane.getVerticalScrollBar();
vertical.setValue(vertical.getMaximum());
}
}
You will get the following exception, if the addNewLine (or the vertical.setValue(...)) method is called from another thread. (Especially, if you're try to resize the window or try to scroll while, autoscroll is enabled)
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at javax.swing.text.BoxView.calculateMajorAxisRequirements(BoxView.java:871)
at javax.swing.text.BoxView.checkRequests(BoxView.java:930)
at javax.swing.text.BoxView.getMinimumSpan(BoxView.java:568)
...
The reason for this is, the multithreaded call of the method is messing up with Swings' eventhandling, so you'll get random results or like above an error (read morehere).
The correct way is to call SwingUtilities.invokeLater(...):
public void addNewLine(String s){
SwingUtilities.invokeLater( () -> {
textPaneOutput.setText(textPaneOutput.getText()+"\n"+s);
if(autoscrollCheckBox.isSelected()){
this.revalidate();
JScrollBar vertical = scrollPane.getVerticalScrollBar();
vertical.setValue(vertical.getMaximum());
}
});
}
This way you'll able to auto scroll threadsafe!
(second question in a few hours)
Kay so I'm making a chess variant in java, I have my console program working how I want it but now I'm trying to convert it to a swing GUI while STILL keeping the console things intact. So up to now I have my array of squares with pieces in them for the console, and a 2-dimensional array of JPanels with pieces in them for the GUI. I haven't implemented moving pieces in the GUI yet so I'm still doing it from the console but the actual GUI doesn't update after I've moved a piece...even though it does on the console (sorry if this is confusing).
The GUI consists of a constructor which calls some methods drawBoard() and drawSidebar() and sets sizes, titles etcetc...so this is what the main method looks like:
public static void main(String args[]) {
ChessGUI GUI = new ChessGUI();
Board console = new Board();
do {
console.printBoard();
console.getScore();
console.getMove();
GUI.boardPanel.revalidate();
GUI.sidePanel.revalidate();
GUI.repaint();
} while (true);
}
and drawBoard() incase it makes any difference:
public void drawBoard() {
LayoutManager layout = new GridLayout(NUMBER_OF_ROWS, NUMBER_OF_COLS);
boardPanel.setLayout(layout);
boardPanel.setPreferredSize(new Dimension(200, 450));
chessBoard = new JPanel[NUMBER_OF_ROWS][NUMBER_OF_COLS];
for (int i = 0; i < NUMBER_OF_ROWS; i++) {
for (int j = 0; j < NUMBER_OF_COLS; j++) {
chessBoard[i][j] = new JPanel();
chessBoard[i][j].setBackground(getColor(i,j));
int index = i * 4 + j;
if (!(boardArray.chessBoard[index].square.isEmpty())) {
Piece piece = (Piece) boardArray.chessBoard[index].square.firstElement();
chessBoard[i][j].add(new JLabel(piece.toString()));
}
boardPanel.add(chessBoard[i][j]);
}
}
}
the repaint and revalidate methods don't seem to be calling at all, even though the console is being updated :(
I don't really understand what you are doing. But it doesn't make sense to recreate the entire board panel every time a move is made. All Swing components can only have a single parent, to the easier solution is to just move the piece from one panel to the other. So the code would be something like:
previousPanel.remove( piece );
currentPanel.add( piece );
previousPanel.revalidate();
previousPanel.repaint();
currentPanel.revalidate();
It looks like you're never actually removing anything from 'boardPanel,' even though you are resetting its LayoutManager.
A safer approach might be to remove 'boardPanel' from its container, then create a new instance for 'boardPanel,' add that to the container, then add the other JPanel pieces to this new 'boardPanel.' Effectively, you would be reconstructing the entire JPanel hierarchy after every move.
As you've noticed, Swing can be quite finicky once you start trying to add/move/remove components after they've been added to containers. For games, often the best approach would be to have 1 JComponent/Component and use Java2D methods to draw on top of it. Swing is typically only used for forms-based applications.
Changing the layout doesn't do anything.
You need to call boardPanel.removeChildren()
However, this is going to be extremely slow.
Really, what you should be doing is have your own JPanel, overwrite paintComponent() and draw the images into the appropriate dimensions using Java Graphics.