Develop Reference

Double click JTable

The cells in my JTable become editable only on the second click. When I debugged I noticed that on the second click the mouse released event is not fired. I saw a lot of answers for this problem with create a setSingleClick(1)... but it doesn't to work. I think that if i can get that second mouseReleased event to get fire i might be able to make it work. Does anybody has any sugestions?
table.addMouseListener(new TableMouseListener()) ;
class TableMouseListener extends MouseAdapter{
public void mousePressed(MouseEvent e) {
System.out.println("mousePressed");
}
public void mouseClicked(MouseEvent e) {
System.out.println("mouseClicked");
}
public void mouseReleased(MouseEvent e) {
System.out.println("mouseReleased");
}
}

Try something like this:
container_table.addMouseListener(new MouseAdapter() {
public void mouseClicked (MouseEvent me) {
if (me.getClickCount() == 2) {
//Double clicked
}
}
});
This way, you know that the 'container_table' has been clicked twice, and then you can get the selected row, and make things with it.
Hope it helps.

Create an actionlistener(?) in Java

So I searched Stackoverflow, but couldn't find any actual answer that I got. If there's already an answer to this question, please tell me.
I have a class with a showDescription method. This prints a string variable.
I require this method to be called whenever the "d" key is pressed, in the main method. So, what would the code be to implement the key press/down event?

Do this if you have a swing application:
f.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
if ((e.getKeyCode() == KeyEvent.VK_D) && ((e.getModifiers() & KeyEvent.CTRL_MASK) != 0)) {
System.out.println("woot!");
}
}
#Override
public void keyReleased(KeyEvent e) {
}
});
you can read more here and here
If you have a console application then use:
Read Input until control+d

Java - keyboard state after leaving window

The title might be a little misleading, didnt know how to put my problem short.
Basically what im doing is im using keyboardlistener to find out which keys are down and according to that im moving my game character.
The problem is, when you click out of the window, while holding down a key my listener doesnt register the keyReleased event.
I tried to fix it by using mouse listener and the mouseExited event, but that doesnt fix it all the time, sometimes it does sometimes it doesnt.
Heres my implementation:
Keyboard:
public void mouseLeftWindow()
{
for(int i =0;i<KEY_COUNT;i++)
{
keys[i] = false;
}
}
#Override
public void keyPressed(KeyEvent e)
{
int keyCode = e.getKeyCode();
if(keyCode>=0 && keyCode<KEY_COUNT)
{
keys[keyCode] = true;
}
}
#Override
public void keyReleased(KeyEvent e)
{
int keyCode = e.getKeyCode();
if(keyCode>=0 && keyCode<KEY_COUNT)
{
keys[keyCode] = false;
}
}
where keys[] is a boolean[] describing, which codes are pressed
mouse:
#Override
public void mouseExited(MouseEvent e)
{
mouseMoved(e);
keyboard.mouseLeftWindow();
}

Your program will listen for further key events even when your mouse exited the component. That means you set everything to false on exit but if a key is still pressed it will be set to true immediately again. I think you are looking for a FocusListener instead of a MouseListener.
addFocusListener(new FocusListener() {
#Override
public void focusGained(FocusEvent e) {
}
#Override
public void focusLost(FocusEvent e) {
keyboard.mouseLeftWindow();
}
});

KeyListener only sometimes works

I am writing a game and I have just tried to add the KeyListener. I have experience with java including KeyListeners but I for some reason cannot figure out why this code only works some of the time.
Here is my listener function:
public void Listener() {
System.out.println("[INFO] Listener() Ran.");
KeyListener kl = new KeyListener() {
public void keyPressed(KeyEvent e) {
if(e.getKeyChar()=='a'){
System.out.println("[DEBUG] A Pressed.");
}
}
public void keyReleased(KeyEvent e) {
}
public void keyTyped(KeyEvent e) {
}
};
panel.addKeyListener(kl);
System.out.println("[DEBUG] panel added KeyListener.");
}
This code works probably only 1 out of 10 times that I run it. Maybe even less. Any ideas on why this is?

The getKeyChar should be called in the keyTyped. The getKeyCode() == KeyEvent.VK_A in the other both methods.

mouse pressed->drag->released. in java

Excuse me:
I just can't know how to link these successive operation?
Mouse pressed and then drag then release. If an user doesn't do this operation some action won't happen...
Should I add code as the is already pressed to distinguish that?
The constant MOUSE_MOVED doesn't work since Eclipse told me it doesn't know it although I find the parameter in mouse event api
I don't know what's going on... Please help!

Implement a MouseInputListener using a MouseInputAdapter subclass and handle the mousePressed, mouseDragged, and the mouseReleased events.
Take a look at this tutorial for examples.

Here is a simple class that encapsulates the drag detection:
public abstract static class MouseDragListener {
java.awt.Component component;
MouseEvent dragStart;
public MouseDragListener(java.awt.Component component) {
super();
this.component = component;
component.addMouseMotionListener(new MouseAdapter() {
public void mouseMoved(MouseEvent e) {
dragStart = null;
}
public void mouseDragged(MouseEvent e) {
if (dragStart == null)
dragStart = e;
}
});
component.addMouseListener(new MouseAdapter() {
public void mouseReleased(MouseEvent e) {
if (dragStart != null) {
dragReleased(dragStart, e);
}
}
});
}
then to use:
new MouseDragListener(center){
void dragReleased(MouseEvent start,MouseEvent end){
// do something ...
}
}