Set background color in Java on a JPanel doesn't work -

i working on "paint-like" application (a little drawing software) familiarize java 2d components. here problem: have jframe contentpane instance of class inheriting jpanel. want set background color white remains on default color... class name corresponding contentpane container. here simplified code:

public class container extends jpanel {      public container() {         super();         this.setbackground(color.white);     } } 

the jframe constructor contains line:

this.setcontentpane(maincontainer); 

have missed something?

thx.

this fix it...

public class container extends jpanel {     public container()      {         super();         this.setopaque(true);         this.setbackground(color.white);     } }