Swing/AWT/SWT :: Why Delays In Drawing Images

I have a question about the execution of code to draw images relative to code that comes after that. I don't normally do this sort of thinghere's the problematic code:

int stn = 0;
while (stn < 10)
{
glb1.xOfText += 20;
glb1.yOfText += 20;
gc1.drawImage(glb1.img1 , glb1.xOfText , glb1.yOfText);
TimeKeeper.pause(500);
stn++;
}

Where glb1 is a final reference to an object that holds common data for the game.while its x and y values say they are for text, they are also used for image placement (at least during this testing phase.)

gc1 is the "graphics context" of the canvas that the images are being drawn on.

The person who wrote this said, "When the attached code is run, the calls to TimeKeeper.pause(500), which in turn call Thread.sleep(500), are all executed in row, and then the results of drawing the image 10 times is displayed. (I know because some of the previous image pastes left some visual data behind.)"

I recall from reading about drawing graphics (a long time ago) that drawImage() could take time, but I don't know why the thread does not indeed sleep between calls to drawImage().