Please use the following code to automation seek bar,
/**
* Automates slider or seek bar to the desired value provided
* @param elementType: Element identification type as string (ID,XPATH,CSS etc)
* @param elementName: Element name (ID value, XPATH value etc)
* @param intToSlideValue: Value to which element needs to be slided(0 to 100)
* @author chethanshetty
*/
public void setSliderValue(String elementType, String elementName, int intToSlideValue) {
WebElement seekBar = getElement(elementType, elementName);
//Get start point of seekbar.
int startX = seekBar.getLocation().getX();
//Get vertical location of seekbar.
int yAxis = seekBar.getLocation().getY();
//Set slidebar move to position.
// this number is calculated based on (offset + 3/4width)
int moveToXDirectionAt = intToSlideValue + startX;
//Moving seekbar using TouchAction class.
TouchAction act=new TouchAction(DriverSingleton.getInstance().getMobileDriver());
act.longPress(startX,yAxis).moveTo(moveToXDirectionAt,yAxis).release().perform();
}
The above code makes use of long press to automate seek bar.
For more info please refer this link