MultipleTIFの展開と出力 Java

import javax.imageio.stream.ImageInputStream;
import java.util.Iterator;
import javax.imageio.ImageReader;
import javax.imageio.ImageIO;
import java.io.File;

public class ImageExtract {

    public String filePath;
    public int numImage;

    public ImageExtract(String filePath,String outPath){
        this.filePath = filePath;
        this.numImage = 0;

        try{
            ImageInputStream iis = ImageIO.createImageInputStream(new File(filePath));
            if (iis == null || iis.length() == 0){
          
            }
            Iterator<ImageReader> iterator = ImageIO.getImageReaders(iis);
            if (iterator == null || !iterator.hasNext()) {
            System.out.println("Image file format not supported by ImageIO: " + filePath);
            }
            
            ImageReader reader = (ImageReader) iterator.next();
            iterator = null;
            reader.setInput(iis);

            this.numImage = reader.getNumImages(true);

            for (int i = 0; i < reader.getNumImages(true); i++) {
                ImageIO.write(reader.read(i), "tif", new File(outPath + i + ".tif"));
                System.out.println(outPath + i + ".tif -> successfully saved." );
            }

        } catch (Exception e){
            System.out.println(e);
        }
       
    }

    public static void main(String[] args) {
        ImageExtract imr = new ImageExtract("img1.tif", "Result/");
    }
}