Apache POI HSLF

POI-HSLF - Java API To Access Microsoft Powerpoint Format Files
Busy Developers' Guide to HSLF drawing layer

import java.io.IOException;

import org.apache.poi.hslf.HSLFSlideShow;
import org.apache.poi.hslf.model.Shape;
import org.apache.poi.hslf.model.Slide;
import org.apache.poi.hslf.model.TextShape;
import org.apache.poi.hslf.usermodel.SlideShow;

public class Main {

  public static void main(String[] args) throws IOException {
    SlideShow ppt = new SlideShow(new HSLFSlideShow(args[0]));
    Slide[] slides = ppt.getSlides();
    for (Slide slide : slides) {
      Shape[] shapes = slide.getShapes();
      for (Shape shape : shapes) {
        if (shape instanceof TextShape) {
          System.out.println(((TextShape) shape).getText());
        }
      }
      System.out.println();
    }
  }

}