We Keep Coding

Java ScrollPane (with a TextArea inside) can not scroll to top programmatically

To abstract this problem, I put 2 buttons. One is called "Add & toTop", another is called "toTop"
And there is no text in the textArea at the very beginning.
And I add the actionListener for "Add & toTop" button like this:
btn1.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
textArea1.setText("jhggjhg\nhugffsrdtfg\ngfdrtdf\nhgftrsdf\nytfresrdcfvg\nuytyrdtesrdfgg\ntdrfygvhct\njh"
+ "gfda\njftyuyiugcf\nhfuygihvftyughbuy\nhgyuftydfhgfyc\ndstryrfdts");
//A long enough String
JScrollBar jb = scrollPane1.getVerticalScrollBar();
jb.setValue(jb.getMinimum());
scrollPane1.repaint();
}
});
So the function of the first button is :"Add some text and Scroll to Top"
But it will only add text but will not scroll to top
However for the second button, I add a actionListener like this:
btn2.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
JScrollBar VerticalScrollBar = scrollPane1.getVerticalScrollBar();
VerticalScrollBar.setValue(VerticalScrollBar.getMinimum());
scrollPane1.repaint();
}
});
So, I press the second button after pressing the first button, the second button will perform well.
And I really feel confused that why the first button will not scroll to top :<

A simple solution might be to use JTextArea#setCaretPosition, for example
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;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JTextArea ta;
public TestPane() {
setLayout(new BorderLayout());
ta = new JTextArea(5, 20);
add(new JScrollPane(ta));
JButton btn = new JButton("Add and to top");
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
ta.setText("jhggjhg\nhugffsrdtfg\ngfdrtdf\nhgftrsdf\nytfresrdcfvg\nuytyrdtesrdfgg\ntdrfygvhct\njh"
+ "gfda\njftyuyiugcf\nhfuygihvftyughbuy\nhgyuftydfhgfyc\ndstryrfdts");
ta.setCaretPosition(0);
}
});
add(btn, BorderLayout.SOUTH);
}
}
}
I had a play around with scrollRectToVisible, but ended up having to use SwingUtilites.invokeLater to make it work, for example...
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
ta.scrollRectToVisible(new Rectangle(0, 0, 10, 10));
}
});
so I'd say setCaretPosition in this case is the simpler solution

Making a slideshow program

I am trying to make a slideshow program. I want the next slide to appear when I click (There are only two slides not, but I will add more once the errors r sorted out).
The code compiles fine. But when i click, nothing happens.
What could possibly go wrong?
package project;
import java.awt.BorderLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
public class Frame extends JFrame{
Frame() {
setLayout(new BorderLayout());
ImageIcon slide = new ImageIcon("E:\\Books\\Computer\\Java\\Introduction to Java Programming\\exercise9e\\image\\slide0.jpg");
JLabel slidesLabel = new JLabel(slide);
add(slidesLabel,BorderLayout.CENTER);
slidesLabel.addMouseListener(new ClickListener());
}
public void nextSlide() {
ImageIcon slide = new ImageIcon("E:\\Books\\Computer\\Java\\Introduction to Java Programming\\exercise9e\\image\\slide1.jpg");
JLabel slidesLabel = new JLabel(slide);
add(slidesLabel,BorderLayout.CENTER);
System.out.println("x");
}
public static void main(String args[]) {
Frame frame = new Frame();
frame.setSize(800,600);
frame.setLocationRelativeTo(null);
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
frame.setVisible(true);
}
public class ClickListener extends MouseAdapter {
#Override
public void mouseClicked(MouseEvent e) {
nextSlide();
}
}
}

So, the "main" problem is BorderLayout will only manage a single component within any of the five available locations it manages.
Adding another component into the position tends to cause issues, where the component that was first added won't be displayed, or in your case, will remain and could interfere with the new component
"A" solution would be to re-use the same JLabel for each slide, simply supply a new value for the icon property (or in this example, the text property)
import java.awt.BorderLayout;
import java.awt.EventQueue;
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.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Frame extends JFrame {
private JLabel slidesLabel = new JLabel("Apple");
public Frame() {
setLayout(new BorderLayout());
add(slidesLabel, BorderLayout.CENTER);
slidesLabel.addMouseListener(new ClickListener());
}
public void nextSlide() {
slidesLabel.setText("Banana");
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
Frame frame = new Frame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ClickListener extends MouseAdapter {
#Override
public void mouseClicked(MouseEvent e) {
nextSlide();
}
}
}
This approach would allow you to place each icon into an array and simply have a counter which determines which slide is current, so when you click for the next slide, you simply increment the counter, get the next value from the array and apply it to the label
A better (and more appropriate) solution would be to actually use a CardLayout, see How to Use CardLayout for more details
With icons...
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Frame extends JFrame {
private JLabel slidesLabel = new JLabel();
private Icon[] icons;
private int currentSlide = -1;
public Frame() {
try {
// Personally, I'd use File#listFiles to list all the
// images in a directory, but that might be consider
// using our initiative...
icons = new Icon[]{
new ImageIcon(ImageIO.read(new File("..."))),
new ImageIcon(ImageIO.read(new File("..."))),
new ImageIcon(ImageIO.read(new File("...")))
};
slidesLabel.setVerticalAlignment(JLabel.CENTER);
slidesLabel.setHorizontalAlignment(JLabel.CENTER);
setLayout(new BorderLayout());
add(slidesLabel, BorderLayout.CENTER);
slidesLabel.addMouseListener(new ClickListener());
nextSlide();
} catch (IOException exp) {
exp.printStackTrace();
}
}
public void nextSlide() {
if (currentSlide < icons.length - 1) {
currentSlide++;
slidesLabel.setIcon(icons[currentSlide]);
}
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
Frame frame = new Frame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class ClickListener extends MouseAdapter {
#Override
public void mouseClicked(MouseEvent e) {
nextSlide();
}
}
}
Why simply adding components to a BorderLayout is bad...
All I did was when nextSlide was called, create a new JLabel assign it the next icon and add it to the Frame (which is using a BorderLayout) and then re-sized the frame. Because the labels are transparent, they remain visible...
This is why you shouldn't simply add new components to a BorderLayout, but, in your case, simply update the properties of the existing JLabel to meet the changing needs.

How to make a border around Jbutton thicker?

I have the following JButton on the GUI interface I'm building.
I want to make the border around the button more thicker so it will stand out from the background. Is it possible to do this in Java?

You could simply use a LineBorder
JButton btn = ...;
btn.setBorder(BorderFactory.createLineBorder(Color.BLACK, 4));
Take a look at How to Use Borders for more details and ideas
Updating the border state based on the model state
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.Border;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public static class TestPane extends JPanel {
protected static final Border NORMAL_BORDER = BorderFactory.createLineBorder(Color.BLACK, 4);
protected static final Border ROLLOVER_BORDER = BorderFactory.createLineBorder(Color.RED, 4);
public TestPane() {
JButton btn = new JButton("Click me!");
btn.setContentAreaFilled(false);
btn.setBorder(NORMAL_BORDER);
btn.getModel().addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
if (btn.getModel().isRollover()) {
btn.setBorder(ROLLOVER_BORDER);
} else {
btn.setBorder(NORMAL_BORDER);
}
}
});
setLayout(new GridBagLayout());
add(btn);
}
}
}

Create a Border first -
Border border = new LineBorder(Color.WHITE, 13);
Then create a JButton and set the Border -
JButton button = new JButton("Button Name");
button.setBorder(border);
Hope it will Help.
Thanks a lot.

How I can define a JRadioButton with large size?

I'm learning java. for my GUI program need to large radio buttons (larger than the standard). What can I do?
I use Java Netbeans IDE - the latest version.

You can supply you're own images for radio button, see JRadioButton#setIcon, JRadioButton#setSelectedIcon and How to Use Buttons, Check Boxes, and Radio Buttons for more details...
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class RadioButtonTest {
public static void main(String[] args) {
new RadioButtonTest();
}
public RadioButtonTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
try {
BufferedImage checked = ImageIO.read(getClass().getResource("/Checked.png"));
Image unchecked = ImageIO.read(getClass().getResource("/Unchecked.png")).getScaledInstance(300, 300, Image.SCALE_SMOOTH);
JRadioButton btn = new JRadioButton("I'm not fat, I'm just big boned");
btn.setSelectedIcon(new ImageIcon(checked));
btn.setIcon(new ImageIcon(unchecked));
btn.setHorizontalTextPosition(JRadioButton.CENTER);
btn.setVerticalTextPosition(JRadioButton.BOTTOM);
setLayout(new GridBagLayout());
add(btn);
} catch (IOException exp) {
exp.printStackTrace();
}
}
}
}

Swing Mouse Click Event for JMenu and JPopupMenu

I would like to have Eclipse behavior for mouse clicks outside menus and popup menus in Swing. Basically, in Eclipse, when you press the mouse OUTSIDE the menu, the menu disappears and the mouse press event is forwarded to the component on which you clicked with the mouse.
Irritatingly, Swing does not do this, and I can't find a way around it.
Right now, even with Windows LAF, i have to click a second time to get the component to register the mouse click.
For the sake of the response just do it on a table
final JPopupMenu popupMenu = new JPopupMenu();
JMenuItem viewProfile = new JMenuItem("View Profile");
viewProfile.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
popupMenu.add(viewProfile);
table.setComponentPopupMenu(popupMenu);
EDIT: here is a test code. I don't think it is convenient to add a mouse listener to every simple component so they can register mouse clicks after a popup menu. In the following example, the Table does implement it, but not the Button.
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.table.DefaultTableModel;
public class TestMouse {
public static void main(String[] args) {
new TestMouse();
}
private JLabel counter;
private int count;
private JPanel northPanel;
private JButton clickMe;
public TestMouse() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
DefaultTableModel model = new DefaultTableModel(new Object[] { "A", "B", "B", "B", "B", "B", "B" }, 10);
JTable table = new JTable(model);
northPanel = new JPanel();
clickMe = new JButton("Button");
clickMe.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("clicked");
count++;
}
});
counter = new JLabel("0");
northPanel.add(counter);
northPanel.add(clickMe);
final JPopupMenu popupMenu = new JPopupMenu();
JMenuItem viewProfile = new JMenuItem("View Profile");
viewProfile.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
popupMenu.add(viewProfile);
table.setComponentPopupMenu(popupMenu);
table.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
System.out.println("clicked");
count++;
counter.setText(String.valueOf(count));
}
});
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(northPanel, BorderLayout.NORTH);
frame.add(new JScrollPane(table));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}

I don't seem to be able to replicate the issue.
When I right click the table, the popup menu appears and when I click the table again (to dismiss the popup), the mouseClicked event is triggered.
Note the counter in the north position...
import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.table.DefaultTableModel;
public class TestMouse {
public static void main(String[] args) {
new TestMouse();
}
private JLabel counter;
private int count;
public TestMouse() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
DefaultTableModel model = new DefaultTableModel(
new Object[]{"A", "B", "B", "B", "B", "B", "B"},
10
);
JTable table = new JTable(model);
counter = new JLabel("0");
final JPopupMenu popupMenu = new JPopupMenu();
JMenuItem viewProfile = new JMenuItem("View Profile");
viewProfile.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
}
});
popupMenu.add(viewProfile);
table.setComponentPopupMenu(popupMenu);
table.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
System.out.println("clicked");
count++;
counter.setText(String.valueOf(count));
}
});
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(counter, BorderLayout.NORTH);
frame.add(new JScrollPane(table));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
A actual runnable example that demonstrates your problem would involve less guess work and better responses

I had exactly the same problem when closing JMenuBar popups, and this worked for me:
UIManager.put("PopupMenu.consumeEventOnClose", false);