DrawLine(...) method generates too many in[] instances

Question

My appplication performs very intensive painting (some kind of real time charts). It often invokes drawLine(...) method of Graphics class. Under profiler I have found out that it instantiate too many int[] (about 300000 every few seconds). Though garbage collector cleans these auxilary instances well, I don't like when it runs every time. How can I write my own drawLine method, which doesn't generate so many auxilary instances? By the way I need to draw only vertical or horizontal lines.

Answer 1

Are you talking about drawing a grid?
If so, 300000 sounds / few seconds sounds like there
is something wrong.
Suppose your screen is 1000x1000 and you are drawing
lines every 10 pixels apart. That is 100 lines in
both directions for 200 lines.
200 lines and 4 ints per call is 800. Assume 100000 /
second, then that means you are calling repaint 125
times / second?
I have about 40 - 50 JFrames, each of them contains panel, which performs painting. Repaint invokes 10-50 times every second for each JFrame. Each repaint draws 1200 lines every time it is invoked. And int[] instances are created inside Swing version of drawLine(...) method, at any case Borland Optimizeit 5.0 says so.
If anything, I would make a temporary line object:
private Line2D line = new Line2D.Double();
public void paint(Graphics _g) {
super.paint(_g);
Graphics2D g = (Graphics2D) _g;
for each horizontal and vertical line:
line.setLine(x1, y1, x2, y2);
g.draw(line);
I've tried your code. Thanks a lot, but it generates too many int[] instances too:(.
>
Also, make sure you are not drawing lines outside of
the area that needs to be repainted. That is, only
draw a line if it would intersect the viewable
rectangle of the panel, or even better if it
intersects the getClipBounds() of the graphics
object.