java - No reason for menu bar to not work? -

in piece of code, have absolutely no idea why menu bar doesn't work, may seem trivial , stupid here, i'll appreciate if can tell me why menu bar not showing..

[bonus] also, have no idea why "add(canvas);" doesn't work, managed find solution research anyways, if possible explanation useful.

package drawer;  import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.border.*;  import java.util.*;  public class drawer { public static void main(string[] args) {          jmenubar menubar; // menu code, doesn't work..         menubar = new jmenubar();          jmenu filemenu = new jmenu("file");         menubar.add(filemenu);          jmenuitem filesavemenu = new jmenuitem("save");         filemenu.add(filesavemenu);           jmenuitem fileloadmenu = new jmenuitem("load");         filemenu.add(fileloadmenu);         jmenuitem fileexitmenu = new jmenuitem("exit");         filemenu.add(fileexitmenu);           jmenu helpmenu = new jmenu("help");           jmenuitem fileaboutmenu = new jmenuitem("about");         helpmenu.add(fileaboutmenu);           jframe mainwindow = new jframe();          flowlayout layoutobj = new flowlayout();         mainwindow.setlayout(layoutobj);         mainwindow.setdefaultcloseoperation(jframe.exit_on_close);         mainwindow.setsize(1600, 900);          mainwindow.setvisible(true);                 jpanel controlpanel = new jpanel();         controlpanel.setlayout(new flowlayout(flowlayout.trailing));              controlpanel.setborder(new titledborder(new etchedborder(), "control panel"));         controlpanel.setpreferredsize(new dimension(200, 750));                       mainwindow.getcontentpane().add(controlpanel);          jpanel canvas = new jpanel();         canvas.setlayout(new flowlayout(flowlayout.center));          canvas.setborder(new titledborder(new etchedborder(), "canvas"));          canvas.setpreferredsize(new dimension(1300, 750));          mainwindow.getcontentpane().add(canvas); // "add(canvas);" doesn't work , solution after researching..            jpanel messagearea = new jpanel();         messagearea.setlayout(new flowlayout(flowlayout.center));              messagearea.setborder(new titledborder(new etchedborder(), "messages"));         messagearea.setpreferredsize(new dimension(1500, 100));         mainwindow.getcontentpane().add(messagearea);     }  } 

add

mainwindow.setjmenubar(menubar); 

at end