Linear targeting in robocode

Question

Can anyone explain me this code? i don't understand condition in the loop while and "predicted X". why predicted_X < 18? what does 18 mean?

while((++deltaTime)*BULLET_SPEED < 
        Point2D.Double.distance(myX, myY, predictedX, predictedY)) {
    predictedX += Math.sin(enemyHeading) * e.getVelocity();
    predictedY += Math.cos(enemyHeading) * e.getVelocity();
    enemyHeading += enemyHeadingChange;
    if(predictedX < 18.0 
            || predictedY < 18.0
            || predictedX > getBattleFieldWidth() - 18.0
            || predictedY > getBattleFieldHeight() - 18.0) {
        predictedX = Math.min(Math.max(18.0, predictedX), 
                getBattleFieldWidth() - 18.0);  
        predictedY = Math.min(Math.max(18.0, predictedY), 
                getBattleFieldHeight() - 18.0);
        break;
    }
}

Answer 1

The robot´s width is 36px so 18.0 is half of it. The condition just makes sure that your predictedX/Y isn´t outside of the battlefield