I am working on a custom JSlider that has a custom Track Rectangle. I want the ability to set the color of the track rectangle when first declaring the slider.
Here's a snippet of what I have (The classes are in separate files in the same package):
public class NewSlider extends JSlider {
Color kolor;
public NewSlider (Color k) {
kolor = k;
}
public void updateUI() {
setUI(new NewSliderUI(this, kolor);
updateLabelUIs();
}
}
public class NewSliderUI extends BasicSliderUI {
Color sliderColor = Color.BLACK;
public NewSliderUI (JSlider b, Color k) {
super(b);
sliderColor = k;
}
}
In the above code, "kolor" is initially null and leads to and error when NewSliderUI tries to use it. It appears that the updateUI() method is called before anything else. Then the NewSlider constructor is called. I have tried a variety of things, but because updateUI() appears to run before anything else, nothing I add to the NewSlider class seems to matter.
If I hardcode a Color (ie. setUI(new NewSliderUI(this, Color.BLACK);), then it works, but having a different class for each color seems silly.
Thanks.
I don't see how kolor could be null unless one of the following are happening:
You're passing a null value to the constructor
You're not instantiating NewSlider in the Swing EDT and are having some strange cache issues
NewSlider is being constructed via reflection/deserialization and kolor is not being set.
Have you tried running this in the debugger with some breakpoints? I'd be curious to ensure that the NewSlider constructor is being called (and before the NewSliderUI constructor).
Edit: I see what you mean below. I forgot that the no args constructor for JSlider was being called implicitly. What about doing the following:
public class NewSlider extends JSlider {
Color kolor = Color.BLACK;
public NewSlider (Color k) {
kolor = k;
updateUI();
}
public void updateUI() {
setUI(new NewSliderUI(this, kolor);
updateLabelUIs();
}
}
You end up calling updateUI() twice, but the end result should be what you want.
Related
In my program I would like the user to be able to change the colour scheme of the program. I have a method which passes in a colour to set the background of all the panels using UIManager.
public void changeColourScheme(Color c) {
UIManager.put("Panel.background", c);
SwingUtilities.updateComponentTreeUI(this);
}
However the issue I'm running into is that it is not changing the colour of the panels. This method is located in the class for the JFrame.
Copied directly from Swing API Docs.
public static void updateComponentTreeUI(Component c)
A simple minded look and feel change: ask each node in the tree
to updateUI() -- that is, to initialize its UI property with the
current look and feel.
Notice the emphasize. Your code doesn't work because you are passing this as the argument to updateComponentTreeUI(). Since you are passing your panel as the argument, only the components inside the panel and the panel itself will get their UI updated. You have to pass the container that holds all other panels in your program, that is your JFrame
public void changeColourScheme(Color c) {
UIManager.put("Panel.background", c);
SwingUtilities.updateComponentTreeUI(frame); //instace of your frame
}
simply because the UIDefaults changes is only effective for the newly created components
for your feature to work you have to make the app restart then before starting the gui change the background in the defaults in the UIManager , or you will have to do it manually (panel by panel).
if you do it manually recursion will help a lot ,like this
private static void loopForPanel(Container c, Color col) {
synchronized (c.getTreeLock()) {
for (Component com : c.getComponents()) {
if (com instanceof JPanel) {
com.setBackground(col);
}
if (com instanceof Container) {
loopForPanel((Container) com,col);
}
}
}
}
then in your changeColourScheme method pass the frame it self for the loopForPanel method with your desired color.
Ok, so, what I've been trying to figure out is how I can make a custom MouseListener for all my buttons that would not require listing every single one of them in the Handler, because I'm going to have a lot of them. Here's the code I have in my Listener as of now:
package com.dinobuilding.handler;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import com.BLANK.BLANKScreen;
import com.BLANK.BLANKWindow;
import com.BLANK.menufeature.Button;
public class ButtonHandler implements MouseListener {
public BLANKWindow dbw;
public BLANK Screen dbs;
static Button button = new Button();
public int buttonX = button.x;
public int buttonY = button.y;
public int buttonSizeX = button.xSize;
public int buttonSizeY = button.ySize;
public ButtonHandler(BLANKWindow dbw, BLANKScreen dbs) {
this.dbw = dbw;
this.dbs = dbs;
}
public static void setButton(Button b) {
button = b;
}
public int mouseEventX;
public int mouseEventY;
Graphics g;
public void mouseClicked(MouseEvent e) {
mouseEventX = e.getLocationOnScreen().x;
mouseEventY = e.getLocationOnScreen().y;
if(mouseEventX <= buttonX && mouseEventX >= buttonX + buttonSizeX) {
if(mouseEventY <= buttonY && mouseEventY >= buttonY + buttonSizeY) {
button.onClicked(dbs, dbw, g);
}
}
}
public void mousePressed(MouseEvent e) {
}
public void mouseReleased(MouseEvent e) {
}
public void mouseEntered(MouseEvent e) {
}
public void mouseExited(MouseEvent e) {
}
And here's the code in the first button that I'm trying to implement:
package com.BLANK.menus;
import java.awt.Color;
import java.awt.Graphics;
import com.BLANK.BLANKScreen;
import com.BLANK.BLANKWindow;
import com.BLANK.handler.ButtonHandler;
import com.BLANK.menufeature.Button;
public class MainMenuPlayButton extends Button {
public static int x;
public static int y;
public static int xSize;
public static int ySize;
public static String s;
public static Graphics g;
public MainMenuPlayButton(int x, int y, int xSize, int ySize, String s, Graphics g) {
super(x, y, xSize, ySize, s, g);
this.x = x;
this.y = y;
this.xSize = xSize;
this.ySize = ySize;
this.s = s;
this.g = g;
setColor(new Color(0, 226, 26));
draw();
}
public MainMenuPlayButton() {
}
public static void draw() {
drawButton(x, y, xSize, ySize, g, s);
ButtonHandler.setButton(new MainMenuPlayButton());
}
public void onClicked(BLANKScreen dbs, BLANKWindow dbw, Graphics g) {
setColor(new Color(216, 0, 0));
}
I think my main problem is that the code in the ButtonHandler gets called before the code in the Button class and therefore the ButtonHandler is utilizing the Button class itself, not the MainMenuPlayButton class. If you need the Button class as well, simply tell me, however I can't imagine why. Thank you in advance!
Edit
Ok, after debugging some, I have found that I in fact have the opposite problem. The button is never being clicked. The getSource() method could work, however I don't really know how to use that and I don't think that I could use that without hardcoding every single button, which is really something I do not want to do.
EDIT 1:
Do you think maybe I could do use the MouseEvent's getX or getXOnScreen? By the way, I registered the ButtonHandler using frame.addMouseListener on my JFrame, so...
EDIT 2:
It would seem that the getX method does not work either. If you could help me on that, I would very much appreciate that.
If you want to get the object that was pressed and tripped the MouseListener, use the MouseEvent's getSource() method. For example, this might work:
public void mouseClicked(MouseEvent e) {
(YourButton) button = (YourButton) e.getSource();
button.onClicked(...);
}
Other bits:
Rename your class from Button to something else, since the Button name clashes with the java.awt.Button class, and this can cause difficult to debug errors.
I cringe any time I see a Graphics field declared in a class, as it suggests possible inappropriate painting. Make sure that you really know what you're doing if you ever use one of these as a field since it's easy to get image loss or a NullPointerException if not used correctly, since the Graphics object is frequently changed by Java, and this change is completely out of your (the programmer's) control. Don't say that you haven't been warned.
Edit
Regarding your comments:
Yes, I do know what I'm doing with the Graphics field, however, if it makes you feel better, know that it's only temporary and I will be changing it to something else later.
OK, I've just been burned on this before. As long as you get it from a BufferedImage and don't try to get it by calling getGraphics() on a component or by pulling it out of a paint or paintComponent method, then you might be OK.
Also, I'm pretty sure that I'm getting the object it clicked correctly, but I can't get it to access the correct subclass of Button. It's only getting the Button class itself, not the MainMenuPlayButton.
Sorry, but this doesn't make sense since you don't get "classes" when you obtain a reference, an object pure and simple, and in fact you would get the very same object that the ButtonListener was added to and that tripped the listener, and the class of this reference will be whatever class your button is. I am assuming that you're adding your MouseListener directly to your "Button" object, correct? Again, time to do some debugging.
Edit 2
Regarding the most recent edit to your question:
Ok, after debugging some, I have found that I in fact have the opposite problem. The button is never being clicked. The getSource() method could work, however I don't really know how to use that and I don't think that I could use that without hardcoding every single button, which is really something I do not want to do.
No, there is no need to hard-code each button, trust me. That's the whole reason for using listeners that are added to the buttons.
EDIT 1: Do you think maybe I could do use the MouseEvent's getX or getXOnScreen? By the way, I registered the ButtonHandler using frame.addMouseListener on my JFrame, so... the
There's one of your problems. If you want to listen to your buttons, you're going to want to be able to register listeners on the button itself. If you have an array or collection of them registering listeners is easy. And no, I don't recommend using x and y on screen since it makes your program extremely fragile. If you did this, any changes to the structure of your GUI would require subsequent hard-code changes to your x and y handling. Ugh.
This begs the question of why create your own Button class, and why not instead use JButtons or a subclass of JButtons. You appear to be re-inventing the wheel, but (sorry to be blunt) creating one that is square.
Edit 3
But you cast the variable to a button, meaning that if I have multiple buttons I have to cast each and every one of them to a different thing.
No absolutely not as the magic of polymorphism should work here. But they're objects of the same type, no? Or do you have many different subclasses of your Button class? And regardless, inside of the mouseClicked(...) method, you appear to want to call only one method on your button, onClicked(...), which I imagine has to be an object of the super class, right? So by calling this method on the current button, It should call its own correct code.
The problem I have with JButton is that they already exist. I can't edit them and I can't customize them, ...
This is patently not true. You can change their appearance and behaviors by many means, including by subclassing or by a factory creation method. Plus they already come with the machinery for being able to register listeners and respond to mouse actions.
...Also, would I have to register/make a new handler for each and every one of the buttons?
Again, you appear to be forgetting that polymorphism should take care of all of this. One handler should do, depending on how well-behaved your code is.
I am going to have a LOT of buttons, and I don't think that that would be a viable solution. If not the getX how would I get it to do something when the thing is clicked?
I've given you my recommendation, other than sometimes it is better to re-write sections of code if the design can be improved, meaning again you may want to consider retrofitting your code to use JButtons.
I'm writing a simple UI just to get the hang of things. I have a tabbed window with two tabs, one has a button that counts up an integer, the other has a text field showing the content of said integer. Or at least that's the plan.
Everything works just fine if I stuff everything into one class. I can access tab 1 from my actionlistener and change the text field in tab 1 from the button press in tab 2. But I don't want my entire program to be in one class, obviously.
And here I have no idea what to do: I need to tell the textfield in the Class Tab1 to change on the button press in the Class Tab2. What's the right thing to do here? My first thought was to hand over an instance of Tab1 in the creation of Tab2, so I could do tab1.changeText(). But that would get messy quickly once I'd get more tabs that interact with each other. So, instead, I want to update the content of the first tab every time it is opened, but I don't know how to do that. And I don't know if that's the right thing to do, either. So, help!
Here's some code. "content" is an instance of Content, a class handling all the logic like adding to the counter.
Main GUI Class:
public class GUI extends JFrame {
//Stuff..
JTabbedPane tabs = new JTabbedPane();
tabs.addTab("One", new Tab1(content));
tabs.addTab("Two", new Tab2(content));
//Stuff..
Tab 1:
public class Tab1 extends JPanel {
public Tab1(Content content) {
JPanel tab1 = new JPanel();
//Stuff..
JTextField tfCount = new JTextField(content.getCounter(), 10);
tab1.add(tfCount);
this.add(tab1);
//Stuff..
Tab 2:
public class Tab2 extends JPanel {
public Tab2(Content content) {
JPanel tab2 = new JPanel();
//Stuff..
JButton btnCount2 = new JButton("Count");
btnCount2.addActionListener(new TestListener(this.content));
tab2.add(btnCount2);
this.add(tab2);
}
private class TestListener implements ActionListener {
Content content;
public TestListener(Content content) {
this.content = content;
}
#Override
public void actionPerformed(ActionEvent e) {
this.content.addToCounter(1);
}
}
Now, if all of that would be in one class (plus subclasses), I could just access tfCount from Tab2 and do tfCount.setText(content.getCounter());. Now tfCount is in a different class, though, and I cannot access it, unless I hand over an instance of Tab1 to Tab2 (like tabs.addTab("Two", new Tab2(content, Tab1);). Couldn't I instead get Tab1 to repaint itself whenever it is opened, like having a method that executes tfCount.setText(content.getCounter()) in Tab1 whenever it is opened, or something along those lines? If so, how do I do that?
With you controls separated in this manner you have a view choices...
You Could...
Share an instance of each "tab" with each of the other tabs, allowing them to either access the others controls or attach listeners across each other. This is very tightly coupled and messy.
The other problem is, does the button really care about the text field or visa versa...
You Could...
Create a simple model that contains the current int value and provides a means to change that value.
The model would have the capacity to fire a ChangeEvent (for example) when the value is changed, which interested parties could listen for and update themselves accordingly.
This decouples the code, reducing the complexity and greatly increasing the flexibility and reuse of various elements of your code.
This is commonly known as an observer pattern and is widely used in Swing.
A possible (listener) example...
For me, I always start with an interface, this describes the absolute minimum requirements that must be meet in order to achieve the required goal. Each tab will want to know the current value, be able to set the next value and listener for changes to the model...
public interface NumberModel {
public int getValue();
public void setValue(int value);
public void addChangeListener(ChangeListener listener);
public void removeChangeListener(ChangeListener listener);
}
An abstract implementation deals with the more "common" implementation details, things that a concrete implementation won't want to have to implement, as it's common enough to all implementations. In this case, that would the listener management...
public abstract class AbstractNumberModel implements NumberModel {
private List<ChangeListener> listeners;
public AbstractNumberModel() {
listeners = new ArrayList<>(25);
}
#Override
public void addChangeListener(ChangeListener listener) {
listeners.add(listener);
}
#Override
public void removeChangeListener(ChangeListener listener) {
listeners.remove(listener);
}
protected ChangeListener[] getChangeListeners() {
// FIFO...
List<ChangeListener> copy = new ArrayList<>(listeners);
Collections.reverse(copy);
return copy.toArray(copy.toArray(new ChangeListener[listeners.size()]));
}
protected void fireStateChanged() {
ChangeListener[] listeners = getChangeListeners();
if (listeners != null && listeners.length > 0) {
ChangeEvent evt = new ChangeEvent(this);
for (ChangeListener listener : listeners) {
listener.stateChanged(evt);
}
}
}
}
And finally, a concrete implementation, which deals with the implementation specific details...
public class DefaultNumberModel extends AbstractNumberModel {
private int value;
public DefaultNumberModel() {
}
public DefaultNumberModel(int value) {
setValue(value);
}
#Override
public int getValue() {
return value;
}
#Override
public void setValue(int num) {
if (num != value) {
value = num;
fireStateChanged();
}
}
}
We could be a slightly more flexible model by doing something like public interface NumberModel<N extends Number> which would allow you define models that could hold Integer, Double, Float and Long for example, but I'll leave that to you.
Each of you tab views will need a setModel(NumberModel) method, so you can pass the model it. In these methods, you will attach a listener to the model and get the current value so that the model and view are in sync.
I'm very new to Java and I'm setting myself the challenge on writing a Caesar shift cipher decoder. I'm basically trying to clear a JTextArea from another class. I have two classes, a GUI class called CrackerGUI and a shift class. The JtextArea is in the GUI class along with the following method:
public void setPlainTextBox(String text)
{
plainTextBox.setText(text);
}
The GUI class also has a clear button with the following:
private void btnClearActionPerformed(java.awt.event.ActionEvent evt) {
Shift classShift = new Shift();
classShift.btnClear();
}
Lastly i have the method in the shift class to clear the JTextArea.
public class Shift extends CrackerGUI {
public void btnClear()
{
CrackerGUI gui = new CrackerGUI();
gui.setPlainText(" ");
System.out.println("testing");
}
}
The testing text is printing out to console but the JTextArea wont clear. I'm not sure as to why :). I am sure it's a very simple mistake but it has me baffled. Any help would be appreciated.
Thank you in advance.
You're misusing inheritance to solve a problem that doesn't involve inheritance. Don't have Shift extend CrackerGUI and don't create a new CrackerGUI object inside of the btnClear() method since neither CrackerGUi is the one that's displayed. Instead have Shift hold a reference to the displayed CrackerGUI object and have it call a public method of this object.
e.g.,
public class Shift {
private CrackerGUI gui;
// pass in a reference to the displayed CrackerGUI object
public Shift(CrackerGUI gui) {
this.gui = gui;
}
public void btnClear() {
//CrackerGUI gui = new CrackerGUI();
gui.setPlainText(" ");
System.out.println("testing");
}
}
You also should probably not be creating new Shift objects in your GUI's actionPerformed methods, but rather use only one Shift object that is a class field.
The btnClear method clears the text area of a new CrackerGUI instance. It's like if you wanted to clear a drawing on a sheet of paper by taking a new blank sheet and clearing it. The original sheet of paper will keep its drawing.
You need to pass the gui instance to your Shift:
public class Shift {
private CrackerGUI gui;
public Shift(CrackerGUI gui) {
this.gui = gui;
}
public void btnClear() {
this.gui.setPlainText(" ");
}
}
and in the CrackerGUI class :
private void btnClearActionPerformed(java.awt.event.ActionEvent evt) {
Shift classShift = new Shift(this);
classShift.btnClear();
}
Assuming CrackerGUI is your GUI, you should have the following instead:
public class CrackerGUI {
public void setPlainTextBox(String text)
{
plainTextBox.setText(text);
}
public void btnClear()
{
setPlainTextBox("");
System.out.println("testing");
}
}
One last thing, never make your GUI elements public! You should ask the GUI to clear itself and leave that knowledge of clearing elements hidden inside it.
You could try using static methods, as you would end up creating a new gui, then displaying that one, in stead of the current one already displayed.
This would require the parent class to be static too, which may cause errors in some of your methods, just a heads up.
Or else, you could create your own setText method:
void setText(JTextField t, String s){
t.setText(s);
}
that may enable you to directly edit components in the current GUI.
I have a public class which has the following method and instance variable:
public void setImagePanel(JPanel value) {
imagePanel = value;
if (imagePanel != null) {
//method 1 : works
imagePanel.addComponentListener(new ComponentAdapter() {
public void componentResized(ComponentEvent evt) {
System.out.println("Here 1");
}
});
//method 2 : does not work
panelResizeListener = new ResizeListener();
imagePanel.addComponentListener(panelResizeListener);
//method 3 : works
//ResizeListener listener = new ResizeListener();
//imagePanel.addComponentListener(listener);
//method 4 : works
//imagePanel.addComponentListener(new ResizeListener());
//method 5 : does not work -- THIS IS THE DESIRED CODE I WANT TO USE
imagePanel.addComponentListener(panelResizeListener);
}
}
public class ResizeListener extends ComponentAdapter {
#Override
public void componentResized(ComponentEvent evt) {
System.out.println("RESIZE 3");
}
}
private ResizeListener panelResizeListener = new ResizeListener();
private static JPanel imagePanel;
Each of the methods above correspond the to code immediately below until the next //method comment. What i don't understand is why i can't use the class instance variable and add that to the JPanel as a component listener.
What happens in the cases above where i say that the method does not work is that i don't get the "RESIZE 3" log messages. In all cases where i list that it works, then i get the "RESIZE 3" messages.
The outer class is public with no other modification except that it implements an interface that i created (which has no methods or variables in common with the methods and variables listed above).
If anyone can help me i would greatly appreciate it. This problem makes no sense to me, the code should be identical.
Man camickr, you were right. Man this was a weird one to solve. There was something else wrong with my code. The order of the methods calls into my class resulted in me adding the listener then another method would end up removing the listener referenced by that variable so of course i would never get events. Thanks a lot for all the help ppl.
I think your problem is that you're declaring panelResizeListener after you're using it. That normally kills just about anything.