java - How to make components in a JPanel stretch as far as possible? -

i'm trying create simple swing program lets user play circle.

here code:

import javax.swing.jframe; import javax.swing.jpanel; import javax.swing.jbutton; import javax.swing.border.border; import javax.swing.borderfactory;  import java.awt.event.mouseevent; import java.awt.event.mouselistener; import java.awt.event.mousemotionlistener;  import java.awt.color; import java.awt.graphics; import java.awt.flowlayout; import java.awt.borderlayout;  public class sixthprogram {     public static void main(string[] args)     {         gui prog=new gui("sixthprogram");         prog.setbounds(350,250,500,250);         prog.setvisible(true);     } }  class gui extends jframe implements mouselistener, mousemotionlistener {     jpanel colorpan, color1, color2, color3 ,color4 ,color5;      int x=3,y=30; // position of circle      public gui(string header)     {         super(header);         setdefaultcloseoperation(jframe.exit_on_close);         setlayout(new borderlayout());          maker();          addmouselistener(this);         addmousemotionlistener(this);          add(colorpan, borderlayout.south);     }      public void maker()     {         colorpan = new jpanel();          border raisedbevel = borderfactory.createraisedbevelborder();         border loweredbevel = borderfactory.createloweredbevelborder();         border compound = borderfactory.createcompoundborder(raisedbevel, loweredbevel);         colorpan.setborder(compound);          colorpan.setlayout(new flowlayout(flowlayout.center));          color1 = new jpanel();         color2 = new jpanel();         color3 = new jpanel();         color4 = new jpanel();         color5 = new jpanel();          color1.setbackground(color.white);         color2.setbackground(color.green);         color3.setbackground(color.red);         color4.setbackground(color.blue);         color5.setbackground(color.black);          colorpan.add(color1);         colorpan.add(color2);         colorpan.add(color3);         colorpan.add(color4);         colorpan.add(color5);      }      @override     public void paint(graphics g)     {         //g.setcolor(color.white);         //g.fillrect(0,0,getwidth(),getheight());         super.paint(g); //do same thing above(clear jframe)          g.setcolor(color.red);         g.filloval(x,y,50,50);     }      public void mouseexited(mouseevent e) //mouselistener overrided methods     {         system.out.println("exit");     }      public void mouseentered(mouseevent e)     {         system.out.println("enter");     }      public void mousereleased(mouseevent e)     {         system.out.println("release");     }      public void mousepressed(mouseevent e)     {         system.out.println("press");             x=e.getx();         y=e.gety();         if(x+50<getwidth() && y+50<getheight()) // preventing out of bounds             repaint();     }      public void mouseclicked(mouseevent e) //press+release=click     {         system.out.println("click");         system.err.println(((jpanel)e.getsource()).getname());     }      public void mousedragged(mouseevent e) //mousemotionlistener overrided methods     {         system.out.println("dragged ("+ e.getx() +","+ e.gety() +")");         x=e.getx();         y=e.gety();         if((x>=3 && y>=30) && (x+50<getwidth() && y+50<getheight())) // preventing out of bounds             repaint();     }      public void mousemoved(mouseevent e)     {         system.out.println("moved ("+ e.getx() +","+ e.gety() +")");     }  } 

i'm trying create jpanel different colors. when clicked on color, circle's color change. i've not yet implemented part.

my problem is, when run above program, output as:

but want output be

i've tried removing

colorpan.setlayout(new flowlayout(flowlayout.center)); 

and resulted in same output.

how stretch components in colorpan, expected output?

instead of flowlayout, can use gridlayout follows:

colorpan.setlayout(new gridlayout(1, 5)); 

this divides width of element in 1 row , 5 columns, 1 per color.