Java robot.mouseMove(x, y) not producing correct results

Question

I have recently been trying to automate a program I made and I have run into a problem, robot.mouseMove(100, 100) doesn't send the mouse to 100, 100.

I made this simple program to show this off:

new Robot().mouseMove(100, 100);
System.out.println(MouseInfo.getPointerInfo().getLocation().getX() + " , "
        + MouseInfo.getPointerInfo().getLocation().getY());

This code produces different results every time I run it:

54.0 , 54.0
0.0 , 0.0
58.0 , 58.0

When you put this in a loop the mouse approaches the correct position. Code :

Robot b = new Robot();  
for (int i = 1; i < 10; i++) {
        b.mouseMove(100, 100);
        System.out.println("Attempt "+i+" : "+MouseInfo.getPointerInfo().getLocation().getX() + " , "
                + MouseInfo.getPointerInfo().getLocation().getY());
    }

Results:

Attempt 1 : 12.0 , 21.0
Attempt 2 : 143.0 , 139.0
Attempt 3 : 79.0 , 81.0
Attempt 4 : 110.0 , 109.0
Attempt 5 : 96.0 , 96.0
Attempt 6 : 101.0 , 102.0
Attempt 7 : 100.0 , 99.0
Attempt 8 : 100.0 , 100.0
Attempt 9 : 100.0 , 100.0
Attempt 10 : 100.0 , 100.0

I don't understand what's going on but any help would be appreciated. Thanks. And just to clarify I am running Windows 10 and Java version 1.8.0_161. My ThinkPad E460 screen is 1920x1080 with 150% scale. Changing the scale does not affect the problem, however, it appears that lowering my screen resolution to the lowest possible (800x600) the mouse pointer is put a lot closer to the spot it is told. This may just be because there are fewer pixels and less room for error.

Results on 800x600 screen:

Attempt 1 : 101.0 , 101.0
Attempt 2 : 99.0 , 100.0
Attempt 3 : 101.0 , 99.0
Attempt 4 : 100.0 , 101.0
Attempt 5 : 99.0 , 99.0
Attempt 6 : 101.0 , 101.0
Attempt 7 : 100.0 , 99.0
Attempt 8 : 99.0 , 101.0
Attempt 9 : 101.0 , 99.0
Attempt 10 : 99.0 , 101.0

EDIT: Unfortunately creating a new robot each loop isn't the problem. I have updated the code (and the results just to be thorough).

EDIT 2: Just updated Java from 1.8.0_151 to 1.8.0_161, the same problem continues.

EDIT 3: I found some questions which might be linked to this problem here and here, they seem to be having a similar problem to me (their robot class isn't moving the mouse to where they want it).

Answer 1

The JDK Bug website says a current workaround is to call the function in a loop until the mouse moved to the right space. You could use a function like this:

public static void moveMouse(int x, int y, int maxTimes, Robot screenWin) {
    for(int count = 0;(MouseInfo.getPointerInfo().getLocation().getX() != x || 
            MouseInfo.getPointerInfo().getLocation().getY() != y) &&
            count < maxTimes; count++) {
        screenWin.mouseMove(x, y);
    }
}

Max times is there to stop an infinite loop in case something happens. Usually 4-5 times is good enough for me.

Answer 2

Probably you do not need to point at exact pixel, and you may allow a bit difference. So, allow it and it will take much less tries. I have two 1080 monitors 100% scale and use a loop to check position with a limit of 100 tries. Some time it reaches the limit without right positioning, in my case. So I modified a loop to allow a difference in 3 points (I do not need really exact positioning) and now it moves mouse near the right spot in less than 10 attempts.

        for (int ntry = 0; ntry < moveTryMax; ntry++) {
            bot.mouseMove(paramVO.getX(), paramVO.getY());
            Point testPoint = MouseInfo.getPointerInfo().getLocation();

            if (Math.abs(testPoint.x - paramVO.getX()) <= pointsDeltaMax && Math.abs(testPoint.y - paramVO.getY()) <= pointsDeltaMax) {
                if (showMessages) {
                    System.out.println("N try: " + ntry);
                }
                break;
            }
        }