import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;

public class BufferedImageToFile {

    public static void main(String[] args) {
        BufferedImageToFile bIF = new BufferedImageToFile();
        bIF.saveBI(bIF.createBI(), "testbild.png", "png");
    }

    private BufferedImage createBI() {
        BufferedImage bi = null;
        try {
            bi = ImageIO.read(new File("img/test.jpg"));
        } catch (IOException e) {
            System.err.println("Datei nicht lesbar!");
        }
        return bi;
    }

    private void saveBI(BufferedImage bi, String path, String type) {
        if (bi != null) {
            File imageFile = new File(path);
            try {
                if (imageFile.createNewFile()) {
                    ImageIO.write(bi, type, imageFile);
                }
            } catch (IOException e) {
                System.err.println("Datei konnte nicht gespeichert werden!");
            }
        } else {
			System.err.println("BufferedImage ist null");
		}
    }
}