java - JList render invisible "selection marker" -

the jlist supports multiple selection when holding control key: press ctrl+up/down move invisible marker (nimbus laf). if no press space, element gets selected.

example: jlist has 3 elements, first 1 selected. know press ctrl + down, ctrl + down , space. last element selected.

the question is: how can render invisible marker move ctrl+up/down?

for example windows file explorer renders marker dotted border , render similar. thing ctrl + up/down don't change selection change element selected/deselected if press space.

defaultlistcellrenderer automatically using special border. if want change border, can change appropriate setting of l&f in uimanager.

import java.awt.basicstroke; import java.awt.color; import java.awt.component;  import javax.swing.jframe; import javax.swing.jlist; import javax.swing.jscrollpane; import javax.swing.swingutilities; import javax.swing.uimanager; import javax.swing.border.strokeborder;  public class listtryout {      public static void main(string[] args) {         swingutilities.invokelater(new runnable() {              @override             public void run() {                 uimanager.put("list.focuscellhighlightborder", borderfactory.createdashedborder(color.gray));                 final jframe f = new jframe();                 f.setdefaultcloseoperation(jframe.dispose_on_close);                 f.add(new jscrollpane(new jlist<string>(new string[] {"one", "two", "three"})));                 f.pack();                 f.setvisible(true);             }         });     } } 

if want else can write own renderer.

import java.awt.color; import java.awt.component;  import javax.swing.defaultlistcellrenderer; import javax.swing.jcomponent; import javax.swing.jframe; import javax.swing.jlist; import javax.swing.jscrollpane; import javax.swing.swingutilities;  public class listtryout {      public static void main(string[] args) {         swingutilities.invokelater(new runnable() {              @override             public void run() { //                uimanager.put("list.focuscellhighlightborder", new strokeborder(new basicstroke(2f)));                 final jframe f = new jframe();                 f.setdefaultcloseoperation(jframe.dispose_on_close);                 jlist<string> l = new jlist<string>(new string[] {"one", "two", "three"});                 l.setcellrenderer(new myrenderer());                 f.add(new jscrollpane(l));                 f.pack();                 f.setvisible(true);             }         });     }      private static class myrenderer extends defaultlistcellrenderer {         /**          * {@inheritdoc}          */         @override         public component getlistcellrenderercomponent(jlist<?> list, object value, int index, boolean isselected, boolean cellhasfocus) {             component result = super.getlistcellrenderercomponent(list, value, index, isselected, cellhasfocus);             if (!isselected && cellhasfocus) { // custom highlight of focused not-selected cell                 result.setbackground(color.light_gray);                 ((jcomponent) result).setborder(null);             }             return result;         }     } }