Re: Mouse even on JLists

From:

Jennifer Eden <jennifereden.price@gmail.com>

Newsgroups:

comp.lang.java.programmer

Date:

Sun, 27 Jul 2008 16:57:56 -0700 (PDT)

Message-ID:

<8427a09e-9207-44e2-9f17-b6f3f864b3f9@z66g2000hsc.googlegroups.com>

On Jul 27, 6:59 pm, Alex.From.Ohio.J...@gmail.com wrote:

On Jul 27, 4:14 pm, Jennifer Eden <jennifereden.pr...@gmail.com>
wrote:

On Jul 27, 2:37 pm, Alex.From.Ohio.J...@gmail.com wrote:

On Jul 27, 11:30 am, Aaron Fude <aaronf...@gmail.com> wrote:> Hi,

Suppose that my JList is tall and only has a few items in it so the=

is a lot of white space.
When capturing a mouse even on a JList, how does one tell whether a=

item was clicked or the empty space below?

(There reason why I need this is this functionality: If the user
double clicks on an item, he is taken to an editor window to edit t=

hat

item. If the user clicks on the empty space, a new item is created =

and

then edited.)

Thank you very much in advance!

Aaron

You can't press item which does not exist. Empty space is interpreted
as last item in the list.
But since it's Java anything is possible.
You can add some other listeners to the JList which is still, for
example, Component and, eventually, get what you need.
Like this:

public class Gui {
        public static void main (String []a){
                JFrame frame=new JFrame();
                final JLabel label=new JLabel("Sele=

ct item");

frame.add(label,BorderLayout.NORTH);
final JList list=new JList(new Stri=

ng[]{"one","two"});

list.addListSelectionListener(new Lis=

tSelectionListener(){

public void valueChan=

ged(ListSelectionEvent e) {

label=

..setText((String)list.getSelectedValue());

}});

list.addMouseListener(new MouseListen=

er(){

public void mouseClic=

ked(MouseEvent arg0) {

}
public void mouseEnte=

red(MouseEvent arg0) {

}
public void mouseExit=

ed(MouseEvent arg0) {

}
public void mousePres=

sed(MouseEvent arg0) {

label=

..setText("Mose pressed");

}
public void mouseRele=

ased(MouseEvent arg0) {

                        }});

                frame.add(list);
                frame.setSize(200,200);
                frame.setVisible(true);
        }

}

First click is processed by both listeners and last item is selected
anyway. But it easy could be rearranged with some flag or internal
state of the program.
Even without any complexity second click on empty space gives you wha=

you want.

Of course you can use other listeners or approaches.
That's just first thing which came to my mind.

Alex.http://www.myjavaserver.com/~alexfromohio/

Thanks, but how would you know whether the second click was on the
last item or on the empty space?

That's not about second or third click. It's about having additional
control/listener/approach.

JList does act on each click notifying listeners. When mouse clicked
outside of existing items it assumes that last item was clicked.

But when you listen for mouse too you can see mouse coordinates and
decide was it close enough to last item to actually make selection or
it was empty area. And based on your decision you can even deselect
this last item and act only as for empty area.
Using mouse pressed and released methods you can act before or after
selection listeners acts.
You also can use the same changelistener to catch actual selection
events and compare them to mouselisteners events and calculate actual
size and bounds of real empty area and act accordingly.

After all you can retrieve size and bounds of real JList as real
Component, calculate where empty area is and act accordingly.

Possibilities are endless. Choose one which is comfortable/achievable
for you or ask somebody who's affordable for you (for example me) and,
actually, there is no problem at all.

That's why I love Java. You can do whatever you can imagine. Which is
the only limit.

Alex.
--http://www.myjavaserver.com/~alexfromohio/- Hide quoted text -

- Show quoted text -

Thanks. What methods tell me the coordinates of the actual items in
the list?