It cannot change Image during playing slides

I have more pictures, and I did sevral following:
textSliderView.image(new File("file1.png"));
mDemoSlider.addSlider(textSliderView);

everthing is fine until now.
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But I replaced one of image files, then I hope the slides will also changed. but it's not.
such as above example, I have a new file1.png, and overwrite the file on the hard disk.

then I :
mDemoSlider.removeAllSlides();

then all all files again. but It doesn't work.