Strange System.out.print behavior inside a for loop

Question

I'm trying to create a simple ASCII progress bar in the console that would display like this:
|--------------------------------------------|
============================More equal signs would appear as time goes on. At least this is what I want to happen.
Instead, what happens is, none of the equal signs are printed until the very end, after the for loop in which the System.out.print("=") statement is in, has exited.
This is my code (probably more than necessary is shown, but the important part is the for loop):
    public void addSomeDiffys(int numOfDiffys, int minInt, int maxInt) {
        Diffy currentDiffy;
        System.out.println("\nCreating Diffys.");
        System.out.println("|--------------------------------------------|");
        for (int i=0; i < numOfDiffys; i++) {
            currentDiffy = new Diffy(minInt, maxInt);
            if ((i/(double)numOfDiffys)*100 % 2 == 0)
                System.out.print("=");
            diffyList.add(currentDiffy);           
        System.out.println("\n" + diffyList.size() + " Diffys created.\n");
        System.out.println("Sorting according to highest rating...");
        Collections.sort(diffyList,Diffy.HIGHEST_RATING_ORDER);
        System.out.println("Done.\n");
    }I also tried changing the System.out.print("="); to System.out.println("="); This time it works as expected, its just not very pretty...
I get something like this:
|--------------------------------------------|
=
=
=
=
=
=
=
=
=
=
=
=So again, when I use println, rather than print, the equal signs are printed over time, slowly, as the progress increases. When using print, Nothing happens for a long time, and then suddenly they all appear after the for loop has terminated, which makes no sense.
Thanks for any help.

Answer 1

When using print, Nothing happens
for a long time, and then suddenly they all appear
after the for loop has terminated, which makes no
sense.
Yes it does make sense! The characters are buffered inside the PrintStream and written when there is a full line to write. You could try a flush() after each = is written but I have no confidence that it will make any difference.