The procedure is as follows, there are two problems:
1) the public void paint (Graphics g) will be executed repeatedly, if press in the program to write, so if there are a lot of the Font object is generated, and then quickly abandoned?
2) there is a global object private Font theFont=new Font (null, the Font. PLAIN, 19), if the paint method used in this object, whether can avoid the waste of repeatedly make the Font object?

 import Java awt. *; 

Public class test extends Frame {
Private Image offScreenImage=null; 
Private Font theFont=new Font (null, the Font. PLAIN, 19). 

Public static void main (String [] args) {
The test TTT=new test (); 
TTT. LaunchFrame (); 
} 

Public void launchFrame () {
Enclosing setLocation (400, 10); 
Enclosing setSize (400, 400); 
Enclosing setBackground (Color. LightGray); 
Enclosing setVisible (true); 
New Thread (new PaintThread ()). The start (); 
} 

@ Override 
Public void paint (Graphics g) {
G.s etFont (new Font (null, the Font. PLAIN, 19)); 
} 

@ Override 
Public void update (Graphics g) {
If (offScreenImage==null) {
OffScreenImage=this. CreateImage (900, 800); 
} 
Graphics g_offScreen=offScreenImage. GetGraphics (); 
Color=c g_offScreen. GetColor (); 
G_offScreen. SetColor (Color. LightGray); 
G_offScreen. FillRect (0, 0, 820, 800); 
G_offScreen. SetColor (c); 
Paint (g_offScreen); 
G.d rawImage (offScreenImage, 0, 0, null); 
} 

Private class PaintThread implements Runnable {
@ Override 
Public void the run () {
While (true) {
Repaint (); 
Try {
Thread.sleep (15); 
{} catch InterruptedException (e) 
e.printStackTrace(); 
} 
} 
} 
} 
}