java - Why don't revalidate() & repaint() work like I expect? -

i expect once combobox has been selected, jtable change.

here part of code:

…… chooseaccoutingitemcombobox.addactionlistener(new actionlistener() {             @override             public void actionperformed(actionevent e) {                 changetable();                 jscrollpane.revalidate();                 jscrollpane. repaint();             }              private void changetable() {                 jtable accounttable2 = new jtable(accountbook.getrowdata(startyear, startmonth, endyear, endmonth, (accountingitem) chooseaccoutingitemcombobox.getselecteditem()), accountbook.getcolumnnames());                 accounttable = accounttable2;             }         });     accounttable = new jtable(accountbook.getrowdata(startyear, startmonth, endyear, endmonth, accountintitem), accountbook.getcolumnnames());         jscrollpane = new jscrollpane(accounttable);         add(jscrollpane, borderlayout.center); …… 

and when selected item in combobox, jtable didn't change. why?

yours basic core java mistake, 1 has nothing swing, revalidate or repaint, , core distinction of what difference between java reference variable , reference (or object):

changing object referenced variable have no effect on original object. example, original displayed jtable object, 1 referenced accounttable variable unchanged changing reference accounttable variable holds, , reason gui not change. again understand it's not variable that's displayed, rather object

to achieve goal instead want change state of displayed jtable. changing model.

i.e., doing like:

private void changetable() {     // create new table model     mytablemodel newmodel = new mytablemodel(pertinentparameters);      // use new model set model of displayed jtable     accounttable.setmodel(newmodel); } 

use parameters you're passing new jtable:

accountbook.getrowdata(startyear, startmonth, endyear, endmonth,        (accountingitem) chooseaccoutingitemcombobox.getselecteditem()),        accountbook.getcolumnnames() 

to create new tablemodel instead.

in fact might able create defaulttablemodel directly data, like:

defaulttablemodel model = new defaulttablemodel(accountbook.getrowdata(      startyear, startmonth, endyear, endmonth,       (accountingitem) chooseaccoutingitemcombobox.getselecteditem()),       accountbook.getcolumnnames()); accounttable.setmodel(model);