java - How to force JContainer to re-layout itself? -

i have jframe borderlayout: jtextarea in north , jbutton in south. pack() in beginning.

my code changes font size text area. how force dialog window , components re-layout itself?

so far tried combinations of:

• another pack()
• repaint()
• revalidate()

it not seem help.

is there guaranteed brute force approach? proper way achieve such result?

update:

while creating scce (see below) found 2 mistakes in original code , fixed them. the frame re-sizing nicely now.

i still have question whether proper way it.

import java.awt.*; import javax.swing.*; import java.awt.event.*;  public class myframe extends jframe implements actionlistener{      private jtextarea txt;     private jbutton bis;     private jframe frame;      int size = 10;      private void buildmaingui() {         txt = new jtextarea("this line of text");         bis = new jbutton("increase size");          jpanel p1 = new jpanel();         bis.addactionlistener(this);          borderlayout bl = new borderlayout();          p1.setlayout(bl);         p1.add(txt, borderlayout.north);         p1.add(bis, borderlayout.south);          frame = new jframe();         frame.setcontentpane(p1);         frame.setvisible(true);         frame.pack();         frame.setdefaultcloseoperation(exit_on_close);     }      @override     public void actionperformed(actionevent e) {          size += 2;         font newfont = new font("courier", font.plain, size);         txt.setfont(newfont);         frame.revalidate();         frame.pack();     }      /**      * @param args      */     public static void main(string[] args) {          myframe mygui = new myframe();          mygui.buildmaingui();     } } 

all 3 alternativer described in actionlistener, lets work easiest of them, seems coordinates same (i think required deepest textlayout ???)

import java.awt.borderlayout; import java.awt.font; import java.awt.event.actionevent; import java.awt.event.actionlistener; import javax.swing.jbutton; import javax.swing.jframe; import javax.swing.jscrollpane; import javax.swing.jtextarea; import javax.swing.swingutilities;  public class resizejtextarea {      private jframe frame = new jframe();     private jscrollpane scrollpane = new jscrollpane();     private jtextarea textarea = new jtextarea(10, 15);     private jbutton button = new jbutton("change");     private font newfont = new font("courier", font.plain, 10);      public resizejtextarea() {         textarea.settext("this line of text");         textarea.setfont(newfont);         button.addactionlistener(new actionlistener() {             @override             public void actionperformed(actionevent e) {                 textarea.setfont(textarea.getfont().derivefont(20f));                  //2. choice                 //textarea.setcolumns(20);                 //textarea.setrows(20);                  //3rd. coice                 //override preferredscrollableviewportsize                 frame.pack();             }         });         scrollpane.setviewportview(textarea);         frame.add(scrollpane);         frame.add(button, borderlayout.south);         frame.setdefaultcloseoperation(jframe.exit_on_close);         frame.setlocation(100, 100);         frame.pack();         frame.setvisible(true);     }      public static void main(string[] args) {         swingutilities.invokelater(new runnable() {             @override             public void run() {                 resizejtextarea fs = new resizejtextarea();             }         });     } }