java - Why can't I add an EmptyBorder to a custom JComponent? -

my code unable set border of custom jcomponent object new emptyborder(50, 50, 50, 50). looks on monitor (as can see, works jbutton not custom jcomponent):

import java.awt.*;  import javax.swing.*; import javax.swing.border.*;  public class sandbox {     public static void main(string[] args)     {         // instantiate components needed.         jframe frame = new jframe();         jpanel panel = new jpanel();         frame.add(panel);         widecomponent wc = new widecomponent();         jbutton button = new jbutton("test");          // add borders         emptyborder empty1 = new emptyborder(50, 50, 50, 50);         wc.setborder(empty1);         emptyborder empty2 = new emptyborder(50, 50, 50, 50);         button.setborder(empty2);          // add stuff panel         panel.add(wc);         panel.add(button);          // add panel frame, show frame         frame.add(panel);         frame.setvisible(true);         frame.pack();     } }  class widecomponent extends jcomponent {     final int width = 500;     final int height = 150;       // drawing method     public void paintcomponent(graphics g)     {         super.paintcomponent(g);         g.setcolor(color.blue);         g.fillrect(0, 0, width, height);     }      // jcomponent sizing methods     public dimension getpreferredsize()     {         return new dimension(width, height);     }     public dimension getmaximumsize() { return getpreferredsize(); }     public dimension getminimumsize() { return getpreferredsize(); }     } 

your borders working fine -- it's empty border being painted blue because you're painting entire component , border part of component. example:

import java.awt.*; import javax.swing.*; import javax.swing.border.*;  public class sandbox {    public static void main(string[] args) {       jframe frame = new jframe();       frame.setdefaultcloseoperation(jframe.dispose_on_close);       jpanel panel = new jpanel();       frame.add(panel);       widecomponent wc = new widecomponent();       jbutton button = new jbutton("test");        wc.setborder(createborder());       button.setborder(createborder());        panel.add(wc);       panel.add(button);        frame.add(panel);       frame.setvisible(true);       frame.pack();    }     private static border createborder() {       border innerborder = borderfactory.createlineborder(color.red);       int eb = 50;       border outerborder = borderfactory.createemptyborder(eb, eb, eb, eb);       border comboborder = borderfactory.createcompoundborder(outerborder,             innerborder);       return comboborder;    } }  class widecomponent extends jcomponent {    final int width = 500;    final int height = 150;     public widecomponent() {       setopaque(true);    }     // drawing method    public void paintcomponent(graphics g) {       super.paintcomponent(g);        g.setcolor(color.blue);        g.fillrect(0, 0, width, height);    }     // jcomponent sizing methods    public dimension getpreferredsize() {       return new dimension(width, height);    }     public dimension getmaximumsize() {       return getpreferredsize();    }     public dimension getminimumsize() {       return getpreferredsize();    } } 

if want blank border around widecomponent, nest inside jpanel, , give border nesting jpanel. instance, code above changed addition of:

  jpanel nestingjpanel = new jpanel();   nestingjpanel.add(new widecomponent());   nestingjpanel.setborder(createborder());    panel.add(wc);   panel.add(button);   panel.add(nestingjpanel);