swing - Prevent vertical spacing when resizing a Java GUI -

i have simple gui , trying create buttons , controls left side of window. right side has text area display content. left side contains buttons , controls user manipulate. have used collection of layout managers (and seem considerably picky) make have now.

i've looked on oracle's documentation on boxlayout left controls' container using, , don't see way prevent buttons spacing apart when window resized. i'd them smashed @ top , stay there without spacing out. boxlayout's 'glue' feature doesn't think does, should called rubber band.

my question is, how keep content on left separating wider , wider screen gets resized?

my gui:

public class testcode extends jframe{  jtextarea textarea = new jtextarea (); jcombobox <string> typecombobox; jtextfield searchfield; jtextfield filefield;  public testcode() {     system.out.println ("in constructor");     settitle ("gui test");     setsize (600, 300);     setdefaultcloseoperation (jframe.exit_on_close);     setvisible (true);      jscrollpane scrollpane = new jscrollpane(textarea);     add(scrollpane, borderlayout.center);      jbutton readbutton = new jbutton("read file");     jbutton displaybutton = new jbutton("display");     jbutton searchbutton = new jbutton("search");       searchfield = new jtextfield(10);     filefield = new jtextfield(15);      typecombobox = new jcombobox <string> ();     typecombobox.additem("index");     typecombobox.additem("type");     typecombobox.additem("name");      jpanel container = new jpanel();         container.setlayout(new boxlayout(container, boxlayout.y_axis));     jpanel filepanel = new jpanel();         filepanel.setlayout(new flowlayout(flowlayout.left));         filepanel.add(new jlabel("source file:", swingconstants.right));         filepanel.add(filefield);         filepanel.add(readbutton);     jpanel displaypanel = new jpanel();         displaypanel.setlayout(new flowlayout(flowlayout.left));         displaypanel.add(new jlabel("display data:", swingconstants.right));         displaypanel.add(displaybutton);     jpanel searchpanel = new jpanel();          searchpanel.setlayout(new flowlayout(flowlayout.left));         searchpanel.add(new jlabel ("search target"));         searchpanel.add(box.createhorizontalbox());         searchpanel.add(searchfield);         searchpanel.add(typecombobox);         searchpanel.add(box.createhorizontalbox());         searchpanel.add(searchbutton);      container.add(filepanel);     container.add(displaypanel);     container.add(searchpanel);     add(container, borderlayout.west);      validate(); } 

boxlayout uses preferredsize minumimu , maximum sizes to layout. in case panel grow preferred size maximum size more space available. prevent happening can do:

filepanel.setmaximumsize( filepanel.getpreferredsize() ); ... displaypanel.setmaximumsize( displaypanel.getpreferredsize() ); ... searchpanel.setmaximumsize( searchpanel.getpreferredsize() ); 

although better solution override getmaximumsize() of each panel return getpreferredsize(). never when might use application in different laf in case preferred size of each panel change.