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Make a JTextField recieve input even with windows not focused

I'm working on a small personal project.
I have two JFrame windows, Viewer and Console.
Viewer only contains a subclass of JPanel, and it should respond to mouse input (clicking, mostly).
Console contains a button, a JTextField (the input), and a JTextArea (the output).
I need to make sure than when I press keys on my keyboard, the corresponding text appears in the Console JTextField, not only when the focus is held by the JTextField, but also when it's held any other component in my app.
In other words, I want the JTextField to accept input even right after I clicked on the Viewer frame.
Is this feasible?
In case that matters, I'm running win 8 x64 and I don't really care about portability (I'm the only one that will ever look at or use this code).
EDIT: here is an example of my code:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class main {
public static Viewer v;
public static Console c;
public static void main(String[] args) {
v=new Viewer();
c=new Console();
}
static class Viewer extends JFrame {
public Viewer(){
setSize(600,600);
getContentPane().add(new myPanel());
addMouseListener(new mouse());
setVisible(true);
}
}
static class myPanel extends JPanel{
public void paintComponent(Graphics g){
g.setColor(new Color((int)(Math.random()*255),(int)(Math.random()*255),(int)(Math.random()*255)));
g.fillRect(0, 0, 600, 600);
}
}
static class Console extends JFrame {
public Console(){
setSize(600,200);
JTextField text=new JTextField();
getContentPane().add(text);
setVisible(true);
}
}
static class mouse implements MouseListener{
#Override
public void mouseClicked(MouseEvent arg0) {
v.repaint();
}
#Override
public void mouseEntered(MouseEvent arg0) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mousePressed(MouseEvent arg0) {
}
#Override
public void mouseReleased(MouseEvent arg0) {
}
}
}
In this example, after I click on the big window to change its color, if I want to write stuff in the other window I have to click on it first.

Can I suggest the KeyboardFocusManager? I've found this to be the easiest way to achieve what I believe you are trying to achieve
KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(
new KeyEventDispatcher() {
public void dispatchKeyEvent(KeyEvent ke) {
//TODO: fill this in
}
});

One inelegant solution is to create a KeyListener, which feeds typed characters to your console, although how exactly this happens depends on how you create your components. For the sake of this example I'll pretend to do it through a static method in your Console class (preferably you'd have access to an instance of Console):
public class ApplicationKeyListener implements KeyListener {
public ApplicationKeyListener() {
}
// Other necessary methods...
public void keyPressed(KeyEvent e) {
char pressed = e.getKeyChar();
Console.feedChar(pressed);
}
}
And then in Console, make sure your JTextField object is global and static, then set up the feedChar() method.
public class Console extends JFrame {
private static JTextField consoleTextField;
public Console() {
consoleTextField = new JTextField();
// ...
}
public static feedChar(char c) {
consoleTextField.setText(consoleTextField.getText() + c.toString());
}
}
Then finally you'd have to add this listener to all JFrames and their children.
public class Viewer extends JFrame {
public Viewer() {
ApplicationKeyListener kl = new ApplicationKeyListener();
addKeyListener(kl);
for (Component child : this.getComponents()) {
child.addKeyListener(kl);
}
}
}

Java: check if the mouse has clicked

i am in trouble with checking if the mouse has clicked with a JFrame. When i use public void mousePressed(MouseEvent e) to print something and i click with the mouse it doesn't print anything. It doesn't gives a error, it just prints nothing out. Here is my code :
import java.awt.event.MouseEvent;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
public class tuna extends JFrame
{
private JTextArea textArea;
public static void main(String[] args)
{
//Run the program
tuna run = new tuna();
run.setDefaultCloseOperation(3);
run.setSize(1200, 1000);
run.setVisible(true);
}
public tuna()
{
super("Simple JFrame");
//add a simple JScrollPane
textArea = new JTextArea(10,10);
JScrollPane scrollPane = new JScrollPane(textArea);
textArea.setEditable(true);
add(scrollPane);
}
//This doesn't print anything when i am clicking in the JFrame
public void mousePressed(MouseEvent e)
{
if(e.getButton() == MouseEvent.BUTTON1)
{
System.out.println("left");
}
else if(e.getButton() == MouseEvent.BUTTON3)
{
System.out.println("right");
}
}
}
Thank you in advance.

You can make you own Mouse Listener and add it to textArea or another component.
For example like this:
public class tuna extends JFrame
{
private JTextArea textArea;
public static void main(String[] args)
{
//Run the program
tuna run = new tuna();
run.setDefaultCloseOperation(3);
run.setSize(1200, 1000);
run.setVisible(true);
}
public tuna()
{
super("Simple JFrame");
//add a simple JScrollPane
textArea = new JTextArea(10,10);
JScrollPane scrollPane = new JScrollPane(textArea);
textArea.setEditable(true);
textArea.addMouseListener(new CustomListener());
add(scrollPane);
}
//This doesn't print anything when i am clicking in the JFrame
public class CustomListener implements MouseListener {
#Override
public void mouseClicked(MouseEvent mouseEvent) {
if(mouseEvent.getButton() == MouseEvent.BUTTON1)
{
System.out.println("left");
}
else if(mouseEvent.getButton() == MouseEvent.BUTTON3)
{
System.out.println("right");
}
}
#Override
public void mousePressed(MouseEvent mouseEvent) {
}
#Override
public void mouseReleased(MouseEvent mouseEvent) {
}
#Override
public void mouseEntered(MouseEvent mouseEvent) {
}
#Override
public void mouseExited(MouseEvent mouseEvent) {
}
}
}

Well there are few issues, in your concept and source code
First you need a MouseListener, so in your case either you can
create a separate MouseListener or use the current JFrame class
itself, like this
public class Tuna extends JFrame implements MouseListener
Also I would recommend to follow proper naming convention and use Tuna instead of tuna.
Then the element you want to respond on the MouseEvents should be
register with the MouseListener created in first step, in your constructor.
textArea.addMouseListener(this);
Also make sure on what element you want to register your
MouseListener, currently your entire Frame is covered by TextArea,
so registering listener on JFrame won't help, instead add it on
JTextArea
Try using #Override annotation where ever possible, editor shows
appropriate compiler errors then, in your case you just wrote,
public void mousePressed(MouseEvent e)
instead of
#Override
public void mousePressed(MouseEvent e)
As this methods works only if you implement an MouseListener
Refer this link for more understanding,
https://docs.oracle.com/javase/tutorial/uiswing/events/mouselistener.html

JFrame in separate class, what about the ActionListener?

I'm trying to separate my Swing GUI from my actual code. In short, I want the user to kick off a process (based on the user's selections); in this case, the JFrame will no longer be needed.
What I couldn't figure out is how to share the user's selection from the GUI.class with the Main.class.
Do you have any advice for me?
Here's my code:
public class Main {
public static void main(String[] args) {
// Show GUI
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
GUI gui = new GUI(templates);
gui.setVisible(true);
}
});
// Kick off a process based on the user's selection
}
}
public class GUI extends JFrame {
private static final long serialVersionUID = 1L;
public GUI(Object[] objects) {
setTitle("GUI");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 350, 100);
setLocationRelativeTo(null);
JPanel cp = new JPanel();
cp.setBorder(new EmptyBorder(10, 10, 10, 10));
setContentPane(cp);
JLabel lbl = new JLabel("Selection:");
cp.add(lbl);
final JComboBox<String> comboBox = new JComboBox<String>(new String[] { "One", "Two", "Three" });
comboBox.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
setVisible(false);
dispose();
// Share the selected item with Main.class
}
});
cp.add(comboBox);
}
}

You could create an object to store the selection result and pass it in to the constructor of the GUI class. Set the selection result in that object before closing the UI and then your Main class could access the value:
public class SelectionResult {
private String selectionResult;
public void setSelectionResult(final String selectionResult) {
this.selectionResult = selectionResult;
}
public String getSelectionResult() {
return this.selectionResult;
}
}
Then, you could modify the GUI constructor like this:
private final SelectionResult selectionResult;
public GUI(Object[] objects, SelectionResult selectionResult) {
this.selectionResult = selectionResult;
...
Create a SelectionResult object in your Main class, and pass it to the constructor of the GUI class. In you GUI class ActionListener, you can then call the setSelectionResult() method with the selected value and that value will be available from the Main class.
You would need to add code to make your main method wait while you are waiting for the value to be set in the UI and then proceed with your logic based on the selection.

A Good way of doing this is use Callback mechanism.
Steps to follow:
create a callback interface
interface Callback {
void execute(Object result);
}
GUI class will implement Callback interface but without providing any implementation
Make GUI class abstract
abstract class GUI extends JFrame implements Callback
Now create an object of GUI class providing actual implementation of Callback interface
Here you can use Anonymous class
GUI gui = new GUI() {
#Override
public void execute(Object result) {
System.out.println("You have selected " + result);
}
};
You can pass any thing in execute() method of Callback.
comboBox.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
setVisible(false);
dispose();
// Share the selected item with Main.class
// Callback
execute(comboBox.getSelectedItem());
}
});
Here Main class is responsible for capturing the response of Callback that is directed by GUI class.
Here is the code:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
public class Main {
public static void main(String[] args) {
// Show GUI
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
GUI gui = new GUI() {
#Override
public void execute(Object result) {
System.out.println("You have selected " + result);
}
};
gui.setVisible(true);
}
});
// Kick off a process based on the user's selection
}
}
interface Callback {
void execute(Object result);
}
abstract class GUI extends JFrame implements Callback {
private static final long serialVersionUID = 1L;
public GUI() {
setTitle("GUI");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(100, 100, 350, 100);
setLocationRelativeTo(null);
JPanel cp = new JPanel();
cp.setBorder(new EmptyBorder(10, 10, 10, 10));
setContentPane(cp);
JLabel lbl = new JLabel("Selection:");
cp.add(lbl);
final JComboBox comboBox = new JComboBox(new String[] { "One", "Two", "Three" });
comboBox.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
setVisible(false);
dispose();
// Share the selected item with Main.class
execute(comboBox.getSelectedItem());
}
});
cp.add(comboBox);
}
}

MouseMotionListener in child component disables MouseListener in parent component

I need help to understand the event propagation in Swing. I know that each event is handled by only one component. Thus, when I have a panel outside with some child panel inside and I add mouseListeners to both of them, the one of inside will be called. That's nice and that's the expected behavior.
But I don't understand the behavior in the following situation:
inside registers a MouseMotionListener and outside registers a MouseListener. I expect inside to consume all MouseMotionEvents and outside to receive the MouseEvents, because there is no listener for normal MouseEvents on inside. But that's not the case, inside somehow consumes all MouseEvents not only the MouseMotionEvents.
The following code illustrates the problem:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class EventTest {
public static void main(String... args) {
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run() {
JComponent inside = new JPanel();
inside.setBackground(Color.red);
inside.setPreferredSize(new Dimension(200,200));
MouseMotionListener mm = new MouseMotionListener() {
#Override
public void mouseDragged(MouseEvent arg0) {
System.err.println("dragged");
}
#Override
public void mouseMoved(MouseEvent arg0) {
System.err.println("moved");
}
};
// next line disables handling of mouse clicked events in outside
inside.addMouseMotionListener(mm);
JComponent outside = new JPanel();
outside.add(inside);
outside.setPreferredSize(new Dimension(300,300));
outside.addMouseListener( new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
System.err.println("clicked");
}
});
JFrame frame = new JFrame();
frame.add(outside);
frame.pack();
frame.setVisible(true);
}
});
}
}
I could work around the problem by registering a listeners on inside for all events the parent component might be interested in and then calling dispatchEvent to forward the event to the parent.
a) can someone point me to some docs, where this behavior is described? The javadocs of MouseEvent made me think that my expectations were right. So, I need a different description to understand it.
b) is there a better solution than the one sketched above?
Thanks,
Kathrin
Edit: It is still unclear, why Swing behaves this way. But as it looks, the only way to get the stuff working is to manually forward the events, I will do it.

a) By design, Java mouse events "bubble up" only if there in no mouse listener on the child component.
b) You can forward events to another component, as shown here and below.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class EventTest {
public static void main(String... args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
final JComponent outside = new JPanel();
JComponent inside = new JPanel();
inside.setBackground(Color.red);
inside.setPreferredSize(new Dimension(200, 200));
inside.addMouseMotionListener(new MouseAdapter() {
#Override
public void mouseDragged(MouseEvent e) {
System.err.println("dragged");
}
#Override
public void mouseMoved(MouseEvent e) {
System.err.println("moved inside");
outside.dispatchEvent(e);
}
});
outside.add(inside);
outside.setPreferredSize(new Dimension(300, 300));
outside.addMouseMotionListener(new MouseAdapter() {
#Override
public void mouseMoved(MouseEvent arg0) {
System.err.println("moved outside");
}
});
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(outside);
frame.pack();
frame.setVisible(true);
}
});
}
}

Very similar to trashgod's answer - you can use a MouseAdapter as your motion listener, and override it to forward any events you want to be handled by the parent. This should only add a minimal amount to your code.
MouseAdapter mm = new MouseAdapter() {
#Override
public void mouseDragged(MouseEvent arg0) {
System.err.println("dragged");
}
#Override
public void mouseMoved(MouseEvent arg0) {
System.err.println("moved");
}
#Override
public void mouseClicked(MouseEvent e) {
outside.dispatchEvent(e);
}
};
// For forwarding events
inside.addMouseListener(mm);
// For consuming events you care about
inside.addMouseMotionListener(mm);
I too couldn't find any way around using the dispatchEvent(e) method. I think you're stuck with that route.

This worked out for me:
Ellipse2D mCircle = new Ellipse2D.Double(x,y,size,size);
void PassMouseEvent(MouseEvent e) {
getParent().dispatchEvent(e);
}
public void mousePressed(MouseEvent arg0) {
if(mCircle.contains(arg0.getX(), arg0.getY())) {
// Do stuff if we click on this object
} else {
// Pass to the underlying object to deal with the mouse event
PassMouseEvent(arg0);
}
}

How to "do something" on Swing component resizing?

I've a class which extends JPanel. I overwrote protected void paintComponent(Graphics g).
There is a variable which has to be recalculated when the panel's dimensions change. How do I do that in a proper way?

Like Adam Paynter suggested, you can also add an inner class to your code, like this:
class ResizeListener extends ComponentAdapter {
public void componentResized(ComponentEvent e) {
// Recalculate the variable you mentioned
}
}
The code you have entered between the innermost brackets will be executed everytime the component get resized.
Then you add this listener to your component with
myJPanel.addComponentListener(new ResizeListener());
You can get your component by using e.getComponent(). This way you can call any method of your component from inside the inner class like
e.getComponent().getWeight();

I suppose you could override the various setSize and resize methods and perform the calculation there. However, you may not find all the places where the size can be changed. You may want to have your class implement ComponentListener and simply listen to itself for resize events.
Warning: I am not a Swing expert.
Warning: I have not compiled this code.
public class MyJPanel extends JPanel implements ComponentListener {
public MyJPanel() {
this.addComponentListener(this);
}
public void paintComponent(Graphics g) {
// Paint, paint, paint...
}
public void componentResized(ComponentEvent e) {
// Perform calculation here
}
public void componentHidden(ComponentEvent e) {}
public void componentMoved(ComponentEvent e) {}
public void componentShown(ComponentEvent e) {}
}

If I understand the question correctly then you should read the section from the Swing tutorial on How to Write a Component Listener which shows you how to listen for a change in a components size.

If the calculation isn't time consuming, I would just re-calculate the value each time in paintComponent().
Otherwise, you can save a value that is the size of the component and check it against the new size in paintComponent. If the size changed, then recalculate, otherwise don't.
private Dimension size;
protected void paintComponent(Graphics g){
if (!size.equals(getSize())){
size = getSize();
// recalculate value
}
}
Or, you can do the calculation on a resize event.
//in the constructor add the line
addComponentListener(resizeListener);
private ComponentListener resizeListener = new ComponentAdapter(){
public void componentResized(ActionEvent e){
// recalculate value
}
};

The simplest way is to implement a ComponentListener:
myjpanel.addComponentListener(new ComponentAdapter() {
#Override
public void componentResized(ComponentEvent e) {
//recalculate variable
}
});
Here, I have used a ComponentAdapter because I only intend on overriding componentResized().

Here's what I use (where CoordinatePlane is a JPanel):
I'm not an expert
public CoordinatePlane() {
setBackground(Color.WHITE);
this.addComponentListener(new ComponentAdapter(){
public void componentResized(ComponentEvent e) {
//YOUR CODE HERE
}
});
}

It resizes automatically if it's
inside a BorderLayout panel and
put there as BorderLayout.CENTER component.
If it doesn't work, you probably have forgotten one of these two.

This simple example is drawing a red circle in the resized frame....
import java.awt.*;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import javax.swing.*;
import java.awt.geom.*;
public class RedCircle extends JFrame implements ComponentListener {
int getWidth;
int getHeight;
public RedCircle() {
super("Red Circle");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
addComponentListener(this);
pack();
setVisible(true);
}
public void componentResized(ComponentEvent e) {
getWidth = e.getComponent().getWidth();
getHeight = e.getComponent().getHeight();
Panel pane = new Panel(getWidth,getHeight);
add(pane);
}
public static void main(String[] args) {
RedCircle rc = new RedCircle();
}
public void componentMoved(ComponentEvent e) {
}
public void componentShown(ComponentEvent e) {
}
public void componentHidden(ComponentEvent e) {
}
}
class Panel extends JPanel {
int panelWidth;
int panelHeight;
public Panel(Integer getWidth,Integer getHeight) {
panelWidth = getWidth;
panelHeight = getHeight;
}
public void paintComponent(Graphics comp) {
super.paintComponent(comp);
Graphics2D comp2D = (Graphics2D) comp;
int realWidth = panelWidth - 17;
int realHeight = panelHeight - 40;
float Height = (realHeight);
float Width = (realWidth);
// draw the Red Circle
comp2D.setColor(Color.red);
Ellipse2D.Float redCircle = new Ellipse2D.Float(0F, 0F, Width, Height);
comp2D.fill(redCircle);
}
}