How can I know when an instance variable raise a event in java? -

i have created class create userinterface of program, program has instance of userinterface.

the useriterface class has listeners, problem need know program main class when instance variable used create user interface raises events example tree valuechanged.

this userinterface class:

    import java.awt.eventqueue;     import javax.swing.jfilechooser;     import javax.swing.jframe;     import javax.swing.jmenubar;     import javax.swing.jmenuitem;     import javax.swing.jtoolbar;     import java.awt.borderlayout;     import javax.swing.jbutton;     import javax.swing.jtree;     import javax.swing.jsplitpane;     import javax.swing.jpanel;     import javax.swing.event.treeselectionevent;     import javax.swing.event.treeselectionlistener;     import javax.swing.filechooser.filenameextensionfilter;     import javax.swing.tree.defaulttreemodel;     import javax.swing.tree.defaultmutabletreenode;     import javax.swing.tree.treeselectionmodel;      import org.eclipse.swt.widgets.tree;      import java.awt.dimension;     import java.awt.event.actionlistener;     import java.awt.event.actionevent;     import java.io.filenotfoundexception;     import java.io.ioexception;       public class userinterfacewindow implements treeselectionlistener{          public jframe frame;         public jtree tree;         public jpanel panel;         public jfilechooser filechooser;         public ifffile ifffile;         public customranaccfile inputrandaccfile;         /**          * create application.          */         public userinterfacewindow() {             initialize();             frame.setvisible(true);         }            /**          * initialize contents of frame.          */         private void initialize() {             frame = new jframe();             frame.setbounds(100, 100, 758, 549);             frame.setdefaultcloseoperation(jframe.exit_on_close);              jtoolbar toolbar = new jtoolbar();             frame.getcontentpane().add(toolbar, borderlayout.north);              jbutton btnopenfile = new jbutton("open file");             btnopenfile.addactionlistener(new openbuttonclick());             toolbar.add(btnopenfile);              jbutton button = new jbutton("new button");             toolbar.add(button);              jsplitpane splitpane = new jsplitpane();             splitpane.setminimumsize(new dimension(300, 25));             frame.getcontentpane().add(splitpane, borderlayout.center);              tree = new jtree();             tree.setmodel(new defaulttreemodel(                 new defaultmutabletreenode("file") {                     /**                      *                       */                     private static final long serialversionuid = 1l;                      {                     }                 }             ));             tree.setminimumsize(new dimension(200, 0));             tree.setmaximumsize(new dimension(200, 64));             tree.getselectionmodel().setselectionmode(treeselectionmodel.single_tree_selection);             tree.addtreeselectionlistener(this);             splitpane.setleftcomponent(tree);              panel = new jpanel();             splitpane.setrightcomponent(panel);         }            public class openbuttonclick implements actionlistener{              @override             public void actionperformed(actionevent e) {                 // todo auto-generated method stub                 if(filechooser==null)                     setupfilechooser();                   if(filechooser.showopendialog(frame)==jfilechooser.approve_option){                      try {                         if(inputrandaccfile!=null)                             inputrandaccfile.close();                         inputrandaccfile= new customranaccfile(filechooser.getselectedfile(),"rw");                         ifffile=iffutils.createifffileinfo(inputrandaccfile);                         iffutils.obtainsubfilelist2k14(ifffile, inputrandaccfile);                         userinterfacewindow.this.settreeelements(ifffile,userinterfacewindow.this.tree);                       } catch (filenotfoundexception e1) {                         // todo auto-generated catch block                         e1.printstacktrace();                     } catch (ioexception e1) {                         // todo auto-generated catch block                         e1.printstacktrace();                     }                    }             }         }            public void settreeelements(ifffile ifffile, jtree tree){               defaultmutabletreenode iffnode= new defaultmutabletreenode(ifffile);             defaulttreemodel model= new defaulttreemodel(iffnode, true);               for(iffbasesubfile subfile: ifffile.getsubfilelist()){                  iffnode.add(new defaultmutabletreenode(subfile,false));             }              tree.setmodel(model);         }           public void setupfilechooser(){             filechooser= new jfilechooser();             filechooser.setdialogtitle("select file");             filenameextensionfilter iffcdffilter= new filenameextensionfilter("iff/cdf files","iff","cdf files","cdf");             filechooser.addchoosablefilefilter(iffcdffilter);             filechooser.setacceptallfilefilterused(false);       filechooser.setfilefilter(iffcdffilter);     }       @override     public void valuechanged(treeselectionevent e) {         // todo auto-generated method stub      }    } 

and myprogram:

    public class mymain { userinterfacewindow uiwindow;     /**      * @param args      */     public static void main(string[] args) {         // todo auto-generated method stub         mymain mymain= new mymain();         mymain.uiwindow= new userinterfacewindow();     }  } 

the event treeselectionevent triggered when user clicks on node of tree.