Develop Reference

Java: In AbsoluteLayout, JButtons do no show up until the mouse enters it

I have switched my Layout to a AbsoluteLayout and everything is in place where it needs to be, but when I run my program, my JButtons are invisible until I mouse over them. What should I change so they are always visible, mouse entered or not?
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.UIManager;
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import java.awt.Color;
import java.awt.Cursor;
public class Library extends JFrame implements ActionListener, MouseListener {
private JFrame jf1;
private JPanel jp1;
private JTextField jtf1;
private JTextField jtf2;
private JTextField jtf3;
private JButton jb1;
private JButton jb2;
private JButton jb3;
public Library() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch(Exception ee) {
ee.printStackTrace();
}
JFrame.setDefaultLookAndFeelDecorated(false);
jf1 = new JFrame("Library");
jf1.setVisible(true);
jf1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
jf1.setSize(1080, 900);
jf1.setResizable(true);
jf1.getContentPane().setLayout(null);
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
jf1.setLocation(dim.width/2-jf1.getSize().width/2, dim.height/2-jf1.getSize().height/2);
jp1 = (JPanel) jf1.getContentPane();
jb1 = new JButton("Genre");
jb1.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
jb1.setBounds(345, 11, 150, 60);
jb1.addActionListener(this);
jb2 = new JButton("Author");
jb2.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
jb2.setBounds(494, 11, 150, 60);
jb2.addActionListener(this);
jb3 = new JButton("Title");
jb3.setDefaultCapable(false);
jb3.setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
jb3.setBounds(643, 11, 150, 60);
jb3.addActionListener(this);
jtf2 = new JTextField("Enter Text");
jtf2.setBounds(445, 292, 200, 20);
jtf2.addMouseListener(this);
jtf2.setVisible(false);
jtf3 = new JTextField("Enter Text");
jtf3.setBounds(671, 351, 200, 20);
jtf3.addMouseListener(this);
jtf3.setVisible(false);
jp1.add(jtf2);
jtf1 = new JTextField("Enter Text");
jtf1.setBounds(236, 230, 200, 20);
jtf1.addMouseListener(this);
jtf1.setVisible(false);
jp1.add(jtf1);
jp1.add(jtf3);
jp1.add(jb1);
jp1.add(jb2);
jp1.add(jb3);
jf1.validate();
}
#Override
public void actionPerformed(ActionEvent e) {
Object code = e.getSource();
if (code == jb1) {
jtf1.setVisible(true);
jp1.validate();
}
else if (code == jb2) {
jtf2.setVisible(true);
jp1.validate();
}
else if (code == jb3) {
jtf3.setVisible(true);
jp1.validate();
}
}
public static void main(String[] args) {
Library shoe = new Library();
}
#Override
public void mouseClicked(MouseEvent eee) {
Object mouseCode = eee.getSource();
if(mouseCode == jtf1) {
jtf1.selectAll();
}
if(mouseCode == jtf2) {
jtf2.selectAll();
}
if(mouseCode == jtf3) {
jtf3.selectAll();
}
}
#Override
public void mouseEntered(MouseEvent eee) {}
#Override
public void mouseExited(MouseEvent eee) {}
#Override
public void mousePressed(MouseEvent eee) {}
#Override
public void mouseReleased(MouseEvent eee) {}
}

There are multiple errors in your program:
You're using AbsoluteLayout which in the end it's still a null layout, see Null layout is evil and Why is it frowned upon to use a null layout in Swing?. While absolute positioning might seem like the fastest and easiest way to make complex GUI's for Swing beginners, the more you advance in your program the more errors you'll get due to this. Instead use a Layout Manager or combinations of them along with Empty borders for extra spacing if needed.
You're creating a JFrame object and extending JFrame that, in other words, makes your class a JFrame! There's no need to extend JFrame if you really need to extend something extend a JPanel which can be added later into other components while JFrame can't.
You're making your JFrame visible before you have added all your components to it, that's the reason for your error, and probably the 1st one too. You should make it visible only in the end, after you have added all your components to it.

Set the JFrame visible (jf1.setVisible(true);) after you add all components. (End of your constructor)

Add key bindings to JButtons that get their actions from action commands?

I found a cool way in another question to create a JButton whose actions are written and viewed in an easy way:
public JButton makeToolbarButton(String title, String actionCommand) {
JButton button = new JButton(title);
button.setActionCommand(actionCommand);
button.addActionListener(this);
return button;
}
The class this method is in implements ActionListener, and the buttons commands are assigned by:
public void actionPerformed(ActionEvent e) {
int action = Integer.parseInt(e.getActionCommand());
switch(action) {
case 1:
System.out.println("This button pressed.");
break;
}
}
And the buttons are made by:
JButton button1 = makeToolbarButton("Button 1", "1");
So my question is: can I add KeyStrokes to a button by this method? I tried something like this (inside of the makeToolbarButton method):
button.getInputMap().put(KeyStroke.getKeyStroke("B"), "button_pressed");
button.getActionMap().put("button_pressed", button.getAction());
But I figure this doesn't work because the action command isn't actually assigning an action to a specific button. Is there a way to add something to the makeToolbarButton() method and a parameter for the KeyStroke to accomplish this?

I think you're missing the point of the Action API. A Action is intended to provide a single, self contained, unit of work. This means that the actionCommand really isn't required, as when the actionListener event is triggered, you know exactly the context in which it's been executed
I'd also avoid using KeyStroke.getKeyStroke(String), as the text is a verbose description of what you want to do (ie pressed B or something, but needless to say, it's a pain to get right)
So, the following demonstrates how you might use Actions and assign them to a button AND a key binding
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class ActionTest {
public static void main(String[] args) {
new ActionTest();
}
public ActionTest() {
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() {
add(createButton(new ActionOne(), KeyStroke.getKeyStroke(KeyEvent.VK_1, 0)));
add(createButton(new ActionTwo(), KeyStroke.getKeyStroke(KeyEvent.VK_2, 0)));
}
public JButton createButton(Action action, KeyStroke keyStroke) {
JButton btn = new JButton(action);
btn.getInputMap(WHEN_IN_FOCUSED_WINDOW).put(keyStroke, "button_pressed");
btn.getActionMap().put("button_pressed", action);
return btn;
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.dispose();
}
}
public class ActionOne extends AbstractAction {
public ActionOne() {
putValue(NAME, "1");
putValue(Action.ACTION_COMMAND_KEY, "Action.one");
}
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(e.getActionCommand());
}
}
public class ActionTwo extends AbstractAction {
public ActionTwo() {
putValue(NAME, "2");
putValue(Action.ACTION_COMMAND_KEY, "Action.two");
}
#Override
public void actionPerformed(ActionEvent e) {
System.out.println(e.getActionCommand());
}
}
}
See How to Use Actions for more details

Select text in 2 JTextarea at the same time

I am trying to do a small app that compares two similar texts contained in 2 JTextarea. I am wondering if it's possible to select text from the first JTextarea and automatically select the text on the second JTeaxtarea (lets consider that it's guarantee that the 2 JTextarea will have the same text for now) ?
Should I share events or listeners ?
Thank you

This would be so much easier if JTextComponent supported a selection model...
Basically, what you can do is attach a ChangeListener to the JTextArea's Caret and monitor for changes to the Caret, changing the selection of the other JTextArea in response...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.DefaultHighlighter;
public class MirrorTextSelection {
public static void main(String[] args) {
new MirrorTextSelection();
}
public MirrorTextSelection() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JTextArea left;
private JTextArea right;
private DefaultHighlighter.DefaultHighlightPainter highlightPainter;
public TestPane() {
highlightPainter = new DefaultHighlighter.DefaultHighlightPainter(UIManager.getColor("TextArea.selectionBackground"));
left = new JTextArea(20, 20);
left.setWrapStyleWord(true);
left.setLineWrap(true);
right = new JTextArea(20, 20);
right.setWrapStyleWord(true);
right.setLineWrap(true);
left.setText("I am trying to do a small app that compares two similar texts contained in 2 JTextarea. I am wondering if it's possible to select text from the first JTextarea and automatically select the text on the second JTeaxtarea (lets consider that it's guarantee that the 2 JTextarea will have the same text for now) ? Should I share events or listeners ? Thank you");
right.setText("I am trying to do a small app that compares two similar texts contained in 2 JTextarea. I am wondering if it's possible to select text from the first JTextarea and automatically select the text on the second JTeaxtarea (lets consider that it's guarantee that the 2 JTextarea will have the same text for now) ? Should I share events or listeners ? Thank you");
setLayout(new GridLayout(0, 2));
add(new JScrollPane(left));
add(new JScrollPane(right));
left.getCaret().addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
int dot = left.getCaret().getDot();
int mark = left.getCaret().getMark();
right.setCaretPosition(mark);
right.moveCaretPosition(dot);
}
});
}
}
}
Now, when you run this, you will find that the right side doesn't seem to get highlighted...what?!
The selection is changing, it's just not been rendered because the component doesn't have focus...
Instead, you could use a Highlighter to highlight the text...
private DefaultHighlighter.DefaultHighlightPainter highlightPainter;
//...
highlightPainter = new DefaultHighlighter.DefaultHighlightPainter(UIManager.getColor("TextArea.selectionBackground"));
left.getCaret().addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
int dot = left.getCaret().getDot();
int mark = left.getCaret().getMark();
right.getHighlighter().removeAllHighlights();
try {
int start = Math.min(dot, mark);
int end = Math.max(dot, mark);
right.getHighlighter().addHighlight(start, end, highlightPainter);
} catch (BadLocationException ex) {
ex.printStackTrace();
}
}
});
Okay, this is now working and you can control the background color of the highlight...
There is another alternative...We can replace the Caret of the right JTextArea with one that doesn't hide the selection when focus is lost...
public class HighlightCaret extends DefaultCaret {
#Override
public void install(JTextComponent c) {
super.install(c);
setSelectionVisible(true);
}
#Override
public void focusGained(FocusEvent e) {
JTextComponent component = getComponent();
if (component.isEnabled()) {
if (component.isEditable()) {
setVisible(true);
}
setSelectionVisible(true);
}
}
#Override
public void focusLost(FocusEvent e) {
setVisible(false);
}
}
Then we set the Caret to right...
right.setCaret(nwe HighlightCaret());
This means we don't need the Highlighter code, we can stick with the original and we get control over not only the background selection color but also the foreground selection color as well...

Needing to return value from user input

a basic problem that i can't figure out, tried a lot of things and can't get it to work, i need to be able to get the value/text of the variable
String input;
so that i can use it again in a different class in order to do an if statement based upon the result
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
public class pInterface extends JFrame {
String input;
private JTextField item1;
public pInterface() {
super("PAnnalyser");
setLayout(new FlowLayout());
item1 = new JTextField("enter text here", 10);
add(item1);
myhandler handler = new myhandler();
item1.addActionListener(handler);
System.out.println();
}
public class myhandler implements ActionListener {
// class that is going to handle the events
public void actionPerformed(ActionEvent event) {
// set the variable equal to empty
if (event.getSource() == item1)// find value in box number 1
input = String.format("%s", event.getActionCommand());
}
public String userValue(String input) {
return input;
}
}
}

You could display the window as a modal JDialog, not a JFrame and place the obtained String into a private field that can be accessed via a getter method. Then the calling code can easily obtain the String and use it. Note that there's no need for a separate String field, which you've called "input", since we can easily and simply extract a String directly from the JTextField (in our "getter" method).
For example:
import java.awt.Dialog.ModalityType;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import javax.swing.*;
import javax.swing.text.JTextComponent;
public class TestPInterface {
#SuppressWarnings("serial")
private static void createAndShowGui() {
final JFrame frame = new JFrame("TestPInterface");
// JDialog to hold our JPanel
final JDialog pInterestDialog = new JDialog(frame, "PInterest",
ModalityType.APPLICATION_MODAL);
final MyPInterface myPInterface = new MyPInterface();
// add JPanel to dialog
pInterestDialog.add(myPInterface);
pInterestDialog.pack();
pInterestDialog.setLocationByPlatform(true);
final JTextField textField = new JTextField(10);
textField.setEditable(false);
textField.setFocusable(false);
JPanel mainPanel = new JPanel();
mainPanel.add(textField);
mainPanel.add(new JButton(new AbstractAction("Get Input") {
#Override
public void actionPerformed(ActionEvent e) {
// show dialog
pInterestDialog.setVisible(true);
// dialog has returned, and so now extract Text
textField.setText(myPInterface.getText());
}
}));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
// by making the class a JPanel, you can put it anywhere you want
// in a JFrame, a JDialog, a JOptionPane, another JPanel
#SuppressWarnings("serial")
class MyPInterface extends JPanel {
// no need for a String field since we can
// get our Strings directly from the JTextField
private JTextField textField = new JTextField(10);
public MyPInterface() {
textField.addFocusListener(new FocusAdapter() {
#Override
public void focusGained(FocusEvent e) {
JTextComponent textComp = (JTextComponent) e.getSource();
textComp.selectAll();
}
});
add(new JLabel("Enter Text Here:"));
add(textField);
textField.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
Window win = (Window) SwingUtilities.getWindowAncestor(MyPInterface.this);
win.dispose();
}
});
}
public String getText() {
return textField.getText();
}
}

A Good way of doing this is use Callback mechanism.
I have already posted an answer in the same context.
Please find it here JFrame in separate class, what about the ActionListener?.

Your method is a bit confusing:
public String userValue(String input) {
return input;
}
I guess you want to do something like this:
public String getInput() {
return input;
}
public void setInput(String input) {
this.input = input;
}
Also your JFrame is not visible yet. Set the visibility like this setVisible(true)

JLabel mouse click on icon or text

When it is clicked on JLabel, I want to understand if the click was on "Icon part", or "Text part" of the JLabel, so that different action can be taken. Is there a clever way to do that? Or just I have to solve it relatively with the coordinates of the icon and text?

+1 to #aymeric comment.
What about having two different JLabels
However I do understand why you might be hesitating
negative: requires maintenance of 2 labels.
My clever (:P) solution to this is create your own abstract component - which accepts icon and text as parameters for constructor - by extending JPanel and than adding 2 JLabels to the JPanel, each label has its on MouseAdapter which calls abstract method xxxClicked() (thus any implementing class must override these methods).
Here is an example I made:
import java.awt.FlowLayout;
import java.awt.Image;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ImageIcon ii = null;
try {
//I dont remmend getScaledInstance just used it for speed of code writing
ii = new ImageIcon(ImageIO.read(new URL("http://www.candonetworking.com/java.gif")).getScaledInstance(32, 32, Image.SCALE_SMOOTH));
} catch (Exception ex) {
ex.printStackTrace();
}
MyLabel ml = new MyLabel(ii, "Something") {
#Override
void iconClicked() {
System.out.println("Icon clicked");
}
#Override
void textClicked() {
System.out.println("Text clicked");
}
};
frame.add(ml);
frame.pack();
frame.setVisible(true);
}
});
}
}
abstract class MyLabel extends JPanel {
JLabel iconLabel;
JLabel textLabel;
MouseAdapter iconMA;
MouseAdapter textMA;
public MyLabel(ImageIcon icon, String text) {
iconLabel = new JLabel(icon);
textLabel = new JLabel(text);
iconMA = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent me) {
super.mouseClicked(me);
iconClicked();
}
};
textMA = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent me) {
super.mouseClicked(me);
textClicked();
}
};
iconLabel.addMouseListener(iconMA);
textLabel.addMouseListener(textMA);
add(iconLabel);
add(textLabel);
}
abstract void iconClicked();
abstract void textClicked();
public JLabel getIconLabel() {
return iconLabel;
}
public JLabel getTextLabel() {
return textLabel;
}
}