java - Utilizing GridLayout, JPanel, BorderLayout -

new gui, trying create simple jframe 2 jtextarea instances positioned right next each other , jpanel @ bottom.

import java.awt.*;  import java.awt.event.actionlistener;  import javax.swing.*;   public class demo extends jframe  { private jpanel panel;  private jtextarea jtextarea1;  private jtextarea jtextarea2;  private decisionpanel decisionpanel;  private gridlayout gridlayout; private container container;  public demo() {      super( "demo" );       container mycontainer = new container();       jtextarea1 = new jtextarea();      jtextarea2 = new jtextarea();       gridlayout gridlayout = new gridlayout( 1, 2 );     mycontainer.setlayout( gridlayout );       mycontainer.add( new jscrollpane( jtextarea1 ) );      mycontainer.add( new jscrollpane( jtextarea2 ) );      jframe f = new jframe();      f.add( mycontainer, borderlayout.center);      f.add( decisionpanel, borderlayout.page_end );      f.setsize( 400, 400 );      f.setdefaultcloseoperation( jframe.exit_on_close );      f.setvisible( true );  } } 

jframe not appear. right way add jtextarea objects gridlayout , container used correctly?

start not extending jframe, causing confusion. basically, example code has 2 instances of jframe, 1 been shown on screen when?

you must generating nullpointerexception decisionpanel never initialised.

public class demo { //extends jframe {      private jpanel panel;     private jtextarea jtextarea1;     private jtextarea jtextarea2;     private decisionpanel decisionpanel;     private gridlayout gridlayout;     private container container;      public demo() {          container mycontainer = new container();          decisionpanel = new decisionpanel();         jtextarea1 = new jtextarea();         jtextarea2 = new jtextarea();          gridlayout gridlayout = new gridlayout(1, 2);         mycontainer.setlayout(gridlayout);          mycontainer.add(new jscrollpane(jtextarea1));         mycontainer.add(new jscrollpane(jtextarea2));          jframe f = new jframe("demo");         f.add(mycontainer, borderlayout.center);         f.add(decisionpanel, borderlayout.page_end);         f.setsize(400, 400);         f.setdefaultcloseoperation(jframe.exit_on_close);         f.setvisible(true);     } } 

or, extend jpanel , add demo panel jframe independently, might more preferable depending on trying achieve...

public class demo extends jpanel {      private jpanel panel;     private jtextarea jtextarea1;     private jtextarea jtextarea2;     private decisionpanel decisionpanel;     private gridlayout gridlayout;     private container container;      public static void main(string[] args) {         eventqueue.invokelater(new runnable() {             @override             public void run() {                 try {                     uimanager.setlookandfeel(uimanager.getsystemlookandfeelclassname());                 } catch (classnotfoundexception | instantiationexception | illegalaccessexception | unsupportedlookandfeelexception ex) {                     ex.printstacktrace();                 }                  jframe frame = new jframe("testing");                 frame.setdefaultcloseoperation(jframe.exit_on_close);                 frame.add(new demo());                 frame.pack();                 frame.setlocationrelativeto(null);                 frame.setvisible(true);             }         });     }      public demo() {         setlayout(new borderlayout());         container mycontainer = new container();          decisionpanel = new decisionpanel();         jtextarea1 = new jtextarea();         jtextarea2 = new jtextarea();          gridlayout gridlayout = new gridlayout(1, 2);         mycontainer.setlayout(gridlayout);          mycontainer.add(new jscrollpane(jtextarea1));         mycontainer.add(new jscrollpane(jtextarea2));         add(mycontainer, borderlayout.center);         add(decisionpanel, borderlayout.page_end);     } }