Some knowledge about getContentPane () in java

Swing programs use JFrame objects to implement their windows. The JFrame class is a subclass of the AWT Frame class.
It also adds some unique features of Swing. In Hello Swing, the code for processing JFrame is as follows:
Public HelloSwing (){
JFrame;
JPanel jPanel;
.....
JFrame = new JFrame ("HelloSwing ");
JPanel = new JPanel ();
.......
JFrame. setContentPane (jPanel );
This code is very similar to the code using Frame. The only difference is that you cannot add components to JFrame.
. You can add components to the content pane of JFrame or provide a new content pane.
A content pane is a container that contains visual components of all frames except the menu bar (if any.
To obtain the content pane of A JFrame, use the getContentPane () method. Content pane
(As shown in the previous example), you can use the set ContentPane () method.