Slow re-adding of component

Question

I've recently encountered the following problem: I've written an applet that creates some custom components. During the course of its execution, these components are removed from the screen and another (new) component is added. This all works fine. Then the original components are restored -- and this is where it gets strange. In the Microsoft JVM everything still works fine. However, in the latest sun 1.4 plugin the addition of the existing components (nb these are not being recreated, just re-added) is excrutiatingly slow. Here is the code to re-add the components:
//clear the applet's display area
removeAll();
add(pz); //add the puzzle component
add(ci); //add the Correct-It button component
add(spacerLabel);
add(clue); //add the cluesFurther investigation gave the following startling figures: the code was modified as follows:
removeAll();
long t1 = System.currentTimeMillis();
add(pz);
long t2 = System.currentTimeMillis();
add(ci);
long t3 = System.currentTimeMillis();                    
add(spacerLabel);
long t4 = System.currentTimeMillis();
add(clue);
long t5 = System.currentTimeMillis();
System.out.println("add(pz) = "+(t2-t1));
System.out.println("add(ci) = "+(t3-t2));
System.out.println("add(SpacerLabel) = "+(t4-t3));
System.out.println("add(clue) = "+(t5-t4));The output for a typical run was:
add(pz) = 940
add(ci) = 550
add(SpacerLabel) = 50
add(clue) = 3680
Note that, by comparison, timings for the creation and addition of the "clue" component in the init method of the applet gave a value of almost zero milliseconds.
Can anybody explain this behaviour?

Answer 1

It is an issue with sun's java 1.4. I believe this issue has been fixed for 1.4.2, however if you're using 1.4.0 or 1.4.1 you are kind of stuck with this problem.
Thankfully, there is a "fix" that I have found. Set the component you're adding to be not visible before adding it to your container. Once its added, you can turn visibility back on. This makes adding components very fast again. To use your example,
removeAll();
pz.setVisible(false);
add(pz); //add the puzzle component
pz.setVisible(true);
ci.setVisible(false);
add(ci); //add the Correct-It button component
ci.setVisible(true);
spacerLabel.setVisible(false);
add(spacerLabel);
spacerLabel.setVisible(true);
clue.setVisible(false);
add(clue); //add the clues
clue.setVisible(true);