swing - Java, drag and drop to change the order of panels -

ok have set follows. have java 1.7 project uses javax.swing ui. first project outside of following tutorials, initiative tracker familiar table top. have class extends jpanel (and implements comparable<>) can add dynamically , story different data each class.

the panels added layout, y position depending on how many panels there. added arraylist sort them in order. list can sorted 1 of properties of class.

what running want manually able drag , drop them change order, both in layout , in arraylist. added note can't remove , re-add 1 because lose values saved in class.

toward end made jbutton needs following:

• so long mouse pressed down on button, panel belongs needs dragged mouse.
• when mouse released needs check position , if necessary go spot.

so example

i have tried drop , drag tutorials can't seem find 1 can adjust want.

edit1: tried.

mouselistener listener = new dragmouseadapter(); dragbutton.addmouselistener(listener); dragbutton.settransferhandler(new transferhandler("text")); 

and then

class dragmouseadapter extends mouseadapter {     public void mousepressed(mouseevent e) {         jcomponent c = (jcomponent) e.getsource();         transferhandler handler = c.gettransferhandler();         handler.exportasdrag(c, e, transferhandler.copy);         // todo make swap location drag , drop     } } 

this tutorial , succesfully changes text , not @ want , don't know how change want.

edit2: this tutorial describes want do, except doesn't work. gives following error:

    step 1 of 7: mouse pressed. going export our randomdraganddroppanel draggable. step 2 of 7: returning acceptable transferhandler action. our randomdraganddroppanel accepts copy only. step 3 of 7: casting randomdraganddroppanel transferable. transferable randomdraganddroppanel queried acceptable dataflavors enters drop targets, present target object transfers. step 4 of 7: querying acceptable dataflavors determine available. our example supports our custom randomdraganddroppanel dataflavor. problem lazy loading: randomdraganddroppanel java.lang.classnotfoundexception: randomdraganddroppanel     @ java.lang.class.forname0(native method)     @ java.lang.class.forname(unknown source)     @ java.awt.datatransfer.dataflavor.trytoloadclass(unknown source)     @ java.awt.datatransfer.dataflavor.initialize(unknown source)     @ java.awt.datatransfer.dataflavor.<init>(unknown source)     @ dnd.draganddroppanelsdemo.getdraganddroppaneldataflavor(draganddroppanelsdemo.java:197)     @ dnd.randomdraganddroppanel.gettransferdataflavors(draganddroppanelsdemo.java:392)     @ sun.awt.datatransfer.datatransferer.getformatsfortransferable(unknown source)     @ sun.awt.dnd.sundragsourcecontextpeer.startdrag(unknown source)     @ java.awt.dnd.dragsource.startdrag(unknown source)     @ java.awt.dnd.dragsource.startdrag(unknown source)     @ java.awt.dnd.draggestureevent.startdrag(unknown source)     @ javax.swing.transferhandler$draghandler.draggesturerecognized(unknown source)     @ java.awt.dnd.draggesturerecognizer.firedraggesturerecognized(unknown source)     @ javax.swing.transferhandler$swingdraggesturerecognizer.gestured(unknown source)     @ javax.swing.transferhandler.exportasdrag(unknown source)     @ dnd.draggablemouselistener.mousepressed(draganddroppanelsdemo.java:456)     @ java.awt.component.processmouseevent(unknown source)     @ javax.swing.jcomponent.processmouseevent(unknown source)     @ java.awt.component.processevent(unknown source)     @ java.awt.container.processevent(unknown source)     @ java.awt.component.dispatcheventimpl(unknown source)     @ java.awt.container.dispatcheventimpl(unknown source)     @ java.awt.component.dispatchevent(unknown source)     @ java.awt.lightweightdispatcher.retargetmouseevent(unknown source)     @ java.awt.lightweightdispatcher.processmouseevent(unknown source)     @ java.awt.lightweightdispatcher.dispatchevent(unknown source)     @ java.awt.container.dispatcheventimpl(unknown source)     @ java.awt.window.dispatcheventimpl(unknown source)     @ java.awt.component.dispatchevent(unknown source)     @ java.awt.eventqueue.dispatcheventimpl(unknown source)     @ java.awt.eventqueue.access$200(unknown source)     @ java.awt.eventqueue$3.run(unknown source)     @ java.awt.eventqueue$3.run(unknown source)     @ java.security.accesscontroller.doprivileged(native method)     @ java.security.protectiondomain$1.dointersectionprivilege(unknown source)     @ java.security.protectiondomain$1.dointersectionprivilege(unknown source)     @ java.awt.eventqueue$4.run(unknown source)     @ java.awt.eventqueue$4.run(unknown source)     @ java.security.accesscontroller.doprivileged(native method)     @ java.security.protectiondomain$1.dointersectionprivilege(unknown source)     @ java.awt.eventqueue.dispatchevent(unknown source)     @ java.awt.eventdispatchthread.pumponeeventforfilters(unknown source)     @ java.awt.eventdispatchthread.pumpeventsforfilter(unknown source)     @ java.awt.eventdispatchthread.pumpeventsforhierarchy(unknown source)     @ java.awt.eventdispatchthread.pumpevents(unknown source)     @ java.awt.eventdispatchthread.pumpevents(unknown source)     @ java.awt.eventdispatchthread.run(unknown source) 

here example of drag , drop change order of panels(does not support sorting).

1. dragmouseadapter#mousedragged(...): search drag panel, remove form parent panel , open cursor window.
2. dragmouseadapter#mousereleased(...): search drop location, insert dragging panel, close cursor window.

import java.awt.*; import java.awt.dnd.*; import java.awt.event.*; import java.net.*; import java.util.*; import javax.swing.*;  public class rearrangeorderofpanelstest2 {   public jcomponent makeui() {     box box = box.createverticalbox();     dragmouseadapter dh = new dragmouseadapter();     box.addmouselistener(dh);     box.addmousemotionlistener(dh);      int idx = 0;     (jcomponent c : arrays.aslist(            new jlabel("<html>111<br>11<br>11"),            new jbutton("2"), new jcheckbox("3"), new jtextfield(14))) {       box.add(createtoolbarbutton(idx++, c));     }     jpanel p = new jpanel(new borderlayout());     p.add(box, borderlayout.north);     return p;   }    private static jcomponent createtoolbarbutton(int i, jcomponent c) {     jlabel l = new jlabel(string.format(" %04d ", i));     l.setopaque(true);     l.setbackground(color.red);     jpanel p = new jpanel(new borderlayout());     p.setborder(borderfactory.createcompoundborder(                   borderfactory.createemptyborder(5, 5, 5, 5),                   borderfactory.createlineborder(color.blue, 2)));     p.add(l, borderlayout.west);     p.add(c);     p.setopaque(false);     return p;   }    public static void main(string... args) {     eventqueue.invokelater(new runnable() {       @override public void run() {         createandshowgui();       }     });   }    public static void createandshowgui() {     jframe f = new jframe();     f.setdefaultcloseoperation(windowconstants.exit_on_close);     f.getcontentpane().add(new rearrangeorderofpanelstest2().makeui());     f.setsize(320, 240);     f.setlocationrelativeto(null);     f.setvisible(true);   } }  class dragmouseadapter extends mouseadapter {   private static final int xoffset = 16;   private static final rectangle r1 = new rectangle();   private static final rectangle r2 = new rectangle();   private static rectangle prevrect;   private final jwindow window = new jwindow();   private component draggingcomonent;   private int index = -1;   private component gap;   private point startpt;   private point dragoffset;   private final int gesturemotionthreshold = dragsource.getdragthreshold();    public dragmouseadapter() {     super();     window.setbackground(new color(0, true));   }    @override public void mousepressed(mouseevent e) {     jcomponent parent = (jcomponent) e.getcomponent();     if (parent.getcomponentcount() <= 1) {       startpt = null;       return;     }     startpt = e.getpoint();   }    private void startdragging(jcomponent parent, point pt) {     //get dragging panel     component c = parent.getcomponentat(pt);     index = parent.getcomponentzorder(c);     if (objects.equals(c, parent) || index < 0) {       return;     }     draggingcomonent = c;     dimension d = draggingcomonent.getsize();      point dp = draggingcomonent.getlocation();     dragoffset = new point(pt.x - dp.x, pt.y - dp.y);      //make dummy filler     gap = box.createrigidarea(d);     swapcomponentlocation(parent, c, gap, index);      //make cursor window     window.add(draggingcomonent);     window.pack();      updatewindowlocation(pt, parent);     window.setvisible(true);   }    private void updatewindowlocation(point pt, jcomponent parent) {     point p = new point(pt.x - dragoffset.x, pt.y - dragoffset.y);     swingutilities.convertpointtoscreen(p, parent);     window.setlocation(p);   }    private static int gettargetindex(rectangle r, point pt, int i) {     int ht2 = (int)(.5 + r.height * .5);     r1.setbounds(r.x, r.y,       r.width, ht2);     r2.setbounds(r.x, r.y + ht2, r.width, ht2);     if (r1.contains(pt)) {       prevrect = r1;       return - 1 > 0 ? : 0;     } else if (r2.contains(pt)) {       prevrect = r2;       return i;     }     return -1;   }   private static void swapcomponentlocation(       container parent, component remove, component add, int idx) {     parent.remove(remove);     parent.add(add, idx);     parent.revalidate();     parent.repaint();   }    @override public void mousedragged(mouseevent e) {     point pt = e.getpoint();     jcomponent parent = (jcomponent) e.getcomponent();      //motionthreshold     double = math.pow(pt.x - startpt.x, 2);     double b = math.pow(pt.y - startpt.y, 2);     if (draggingcomonent == null &&         math.sqrt(a + b) > gesturemotionthreshold) {       startdragging(parent, pt);       return;     }     if (!window.isvisible() || draggingcomonent == null) {       return;     }      //update cursor window location     updatewindowlocation(pt, parent);     if (prevrect != null && prevrect.contains(pt)) {       return;     }      //change dummy filler location     (int = 0; < parent.getcomponentcount(); i++) {       component c = parent.getcomponent(i);       rectangle r = c.getbounds();       if (objects.equals(c, gap) && r.contains(pt)) {         return;       }       int tgt = gettargetindex(r, pt, i);       if (tgt >= 0) {         swapcomponentlocation(parent, gap, gap, tgt);         return;       }     }     parent.remove(gap);     parent.revalidate();   }    @override public void mousereleased(mouseevent e) {     startpt = null;     if (!window.isvisible() || draggingcomonent == null) {       return;     }     point pt = e.getpoint();     jcomponent parent = (jcomponent) e.getcomponent();      //close cursor window     component cmp = draggingcomonent;     draggingcomonent = null;     prevrect = null;     startpt = null;     dragoffset = null;     window.setvisible(false);      //swap dragging panel , dummy filler     (int = 0; < parent.getcomponentcount(); i++) {       component c = parent.getcomponent(i);       if (objects.equals(c, gap)) {         swapcomponentlocation(parent, gap, cmp, i);         return;       }       int tgt = gettargetindex(c.getbounds(), pt, i);       if (tgt >= 0) {         swapcomponentlocation(parent, gap, cmp, tgt);         return;       }     }     if (parent.getparent().getbounds().contains(pt)) {       swapcomponentlocation(parent, gap, cmp, parent.getcomponentcount());     } else {       swapcomponentlocation(parent, gap, cmp, index);     }   } }