One night after a long day of sitting and working, I logged on to League to relax (trust me, it is not relaxing). I hit the Find Match button, then ran to the bathroom. If you’ve ever played League of Legends, you know it picks the worst time to show the “Match Accepted” screen. You have about 15 seconds before it auto-declines the game for you.

I missed that window. Got banned.

So I thought, I can automate this.

The Plan

I wanted to build a lightweight Java app that could:

• Watch a fixed region of the screen

• Detect when the Accept button appears

• Click it automatically

I set three rules for myself:

• Keep CPU use very low

• No false positives

For tools, I chose:

• Java 17, with JavaFX for the interface

• java.awt.Robot for screen capture and mouse clicks

• ScheduledExecutorService for the scanning loop

How It Works

1. Capture a small region using Robot.createScreenCapture(rect)

2. Convert it to grayscale and downscale for speed

3. Compare it to the last captured frame

4. If the pixel difference passes a set tolerance, trigger a click

Pseudocode looked something like this:

init UI, load settings

rect = selected region

robot = new Robot()

prev = null

stableHits = 0

every scanInterval ms:

img = robot.createScreenCapture(rect)

diff = meanAbsDiff(prev, img)

prev = img

if diff > tolerance:

stableHits++

else:

stableHits = 0

if stableHits >= debounceCount:

click(rect.center())

stableHits = 0

sleep(cooldown)

This small loop made all the difference. Instead of scanning the whole screen, it focused only on where the Accept button appears, saving a ton of resources.

Building Version 1

Version 1 was pure experimentation. I used raw Swing components, scanned the entire screen, and pushed my CPU to almost 100%. The app clicked when it shouldn’t have, lagged when it should’ve been idle, and stayed open even when I quit the game.

Still, it proved the idea worked.