java - GridBagLayout fix space set by weight x/y -

i have frame following layout of 3 jpanels.

---------------------------- |   |                      | | l |                      | | e |  //toppanel          | | f |                      |    | t |----------------------| | p |                      | | n |  //bottompanel       | | l |                      | |   |                      | ---------------------------- 

i achieved use of gridbaglayout

this code layout

public class uitests extends jframe{     public uitests(){         setlayout(new gridbaglayout());          //the 3 main panels         jpanel leftpanel = new jpanel();         jpanel toppanel = new jpanel();         jpanel bottompanel = new jpanel();          leftpanel.setbackground(color.yellow);         toppanel.setbackground(color.green);         bottompanel.setbackground(color.pink);          //position 3 main panels         gridbagconstraints gbc = new gridbagconstraints();         gbc.gridx = 0;         gbc.gridy = 0;         gbc.gridheight = 2;         gbc.gridwidth = 1;         gbc.fill = gbc.both;         gbc.weightx = .2;         gbc.weighty = 1;         getcontentpane().add(leftpanel, gbc);          gbc = new gridbagconstraints();         gbc.gridx = 1;         gbc.gridy = 0;         gbc.gridheight = 1;         gbc.gridwidth = 1;         gbc.fill = gbc.both;         gbc.weightx = .8;         gbc.weighty = .5;         getcontentpane().add(toppanel, gbc);          gbc = new gridbagconstraints();         gbc.gridx = 1;         gbc.gridy = 1;         gbc.gridheight = 1;         gbc.gridwidth = 1;         gbc.fill = gbc.both;         gbc.weightx = .8;         gbc.weighty = .5;         getcontentpane().add(bottompanel, gbc);           setsize(600,600);         setlocationrelativeto(null);         setdefaultcloseoperation(jframe.exit_on_close);         setvisible(true);     }     public static void main(string[] args){         new uitests();     } } 

problem is, when add jtable in top panel, bottom panel's height shrinked, of height taken top panel. here code table in top panel , added after setting background of 3 main panels.

object[][] contents = {{"haha","hehe", "hihi", "hoho", "huhu"},         {"haha","hehe", "hihi", "hoho", "huhu"},         {"haha","hehe", "hihi", "hoho", "huhu"},         {"haha","hehe", "hihi", "hoho", "huhu"}}; object[] heads = {"haha head", "hehe head", "hihi head", "hoho head", "huhu head"}; jtable table = new jtable(contents, heads); jscrollpane scrolltable = new jscrollpane(table);  //add components toppanel gridbagconstraints gbc = new gridbagconstraints(); gbc.gridx = 0; gbc.gridy = 0; gbc.gridheight = 1; gbc.gridwidth = 1; gbc.weightx = 1; gbc.weighty = 1; gbc.fill = gbc.both; toppanel.setlayout(new gridbaglayout()); toppanel.add(scrolltable, gbc); 

the frame like

---------------------------- |   |                      | | l |                      | | e |  //toppanel          | | f |  //new table created |    | t |                      | | p |                      | | n |                      | | l |----------------------| |   |  //bottompanel       | ---------------------------- 

so, how can make space created 'weightx' or 'weighty' fixed?

weightx/weighty used distribute space. in fact container asks children preferred size , if it's smaller available pixels distributed according weights.

so can define preferred size of jscrollpane holds jtable