java - Class Cast Exception - Mouse event -

a bit of context - creating rudimentary implementation of scrabble , gui relies on java swing , awt. code excerpt below contains constructor cell class (individual space on scrabble board). in proof of concept phase , testing addition , removal of hard-coded letter icon individual cell. each cell individual jpanel jlabel (which, contains imageicon of letter). code looks though works without error, every 5-6 additions/removals (via mouse click) causes class cast exception. specific exception is:

exception in thread "awt-eventqueue-0" java.lang.classcastexception: cell cannot cast javax.swing.jlabel

i can't see exception caused, more why occurs after multiple successful additions , removals. insight appreciated; beginner java gui.

public class cell extends jpanel {  /*tile colors*/ public static color twcolor = new color(255, 0, 0); public static color dwcolor = new color(255, 153, 255); public static color tlcolor = new color(0, 51, 255); public static color dlcolor = new color(102, 204, 255); public static color defaultcolor = new color(255, 255, 255);  private jlabel selected = null; private jlabel clicked = null; private jlabel lettericon; private imageicon defaulticon; private imageicon testimg;  public cell(int xpos, int ypos, int premiumstatus) {      defaulticon = new imageicon ("img/transparent.png");     testimg = new imageicon ("img/test.jpg"); // letter image hard-coded testing     lettericon = new jlabel("", defaulticon, jlabel.center);     add(lettericon);      lettericon.addmouselistener(new mouseadapter() {       public void mouseclicked(mouseevent e) {         jlabel clicked = (jlabel) getcomponentat(e.getpoint());         system.out.println(clicked);         if (clicked == null) {           return;         }         if (selected != null) {           selected.removeall();           selected.revalidate();           selected.seticon(defaulticon);           selected.repaint();           system.out.println("test");           selected = null;           return;         }         if (selected == null) {           selected = clicked;           selected.seticon(testimg);           selected.revalidate();           selected.repaint();         }       }     }); } 

the problem being cause calling getcomponentat(e.getpoint()); on cell, when mouse coordinates have been converted coordinate space of lettericon.

when component clicked, mouseevent's point automatically converted coordinate space of component listener registered to.

in case, lettericon. means point @ 0x0 top/left corner of lettericon (despite might physically positioned).

so, calling getcomponentat(e.getpoint()) ask cell return component corresponds position relative lettericon, (in cases) return cell itself.

instead, should using mouseevent#getcomponent return component triggered event, lettericon

update simple example

this simple example sets jlabel mouse target. when mouse clicked, both label , it's parent container paint small dot based on coordinates of mouse click.

there added benefit parent container translate click point it's coordinate space , paint second dot, should in same click labels.

import java.awt.borderlayout; import java.awt.color; import java.awt.dimension; import java.awt.eventqueue; import java.awt.graphics; import java.awt.gridbaglayout; import java.awt.point; import java.awt.event.mouseadapter; import java.awt.event.mouseevent; import javax.swing.jframe; import javax.swing.jlabel; import javax.swing.jpanel; import javax.swing.swingutilities; import javax.swing.uimanager; import javax.swing.unsupportedlookandfeelexception;  public class testmouseclicked {      public static void main(string[] args) {         new testmouseclicked();     }      public testmouseclicked() {         eventqueue.invokelater(new runnable() {             @override             public void run() {                 try {                     uimanager.setlookandfeel(uimanager.getsystemlookandfeelclassname());                 } catch (classnotfoundexception | instantiationexception | illegalaccessexception | unsupportedlookandfeelexception ex) {                 }                  jframe frame = new jframe("testing");                 frame.setdefaultcloseoperation(jframe.exit_on_close);                 frame.setlayout(new borderlayout());                 frame.add(new testpane());                 frame.pack();                 frame.setlocationrelativeto(null);                 frame.setvisible(true);             }         });     }      public class testpane extends jpanel {          private jlabel clickme;         private point clickpoint;          public testpane() {             setlayout(new gridbaglayout());             clickme = new jlabel("click me") {                 @override                 protected void paintcomponent(graphics g) {                     super.paintcomponent(g);                     g.setcolor(color.magenta); //                    paintpoint(g, clickpoint);                 }             };             add(clickme);             clickme.addmouselistener(new mouseadapter() {                 @override                 public void mouseclicked(mouseevent e) {                     clickpoint = e.getpoint();                     repaint();                 }             });         }          @override         public dimension getpreferredsize() {             return new dimension(200, 200);         }          @override         protected void paintcomponent(graphics g) {             super.paintcomponent(g);             g.setcolor(color.red);             paintpoint(g, clickpoint);             if (clickpoint != null) {                 g.setcolor(color.blue);                 // convert point clickme coordinate space local coordinate space                 paintpoint(g, swingutilities.convertpoint(clickme, clickpoint, this));             }         }          protected void paintpoint(graphics g, point clickpoint) {             if (clickpoint != null) {                 int size = 4;                 g.filloval(clickpoint.x - size, clickpoint.y - size, size * 2, size * 2);             }         }     } }