ImageIO.read returns NULL, with no errors

The following code seems not to work, even though the file appears to be found just fine.

images = new BufferedImage[32];
FileInputStream fis = null;
for (int i = 0; i < 32; i++) {
    File file = new File("tiles\\"+i+".bmp");
    if (!file.exists()){
        System.out.println("File  "+i+" failed");
    }
    try { 
        fis = new FileInputStream(file); 
    } catch (FileNotFoundException e) { 
        System.err.println(e + "" + i); 
    }
    try { 
        images[i] = ImageIO.read(fis); 
    } catch (IOException e) { 
        System.err.println(e + "" + i); 
    }
    if (images[i] == null) {
        System.out.println("Image "+i+" failed");
    }
}

Edit: The result is me attempting to Graphics.drawImage(images[0]);, and it giving me a null pointer exception. This code here completes fine.

Edit: Changed moved the if(!file.exists()) as suggested, and wrapped the file in an input stream.

ImageIO.read(file); will return null if no registered ImageReader is found. Please check whether you have registered any ImageReader.

I think this code snippet could help you

File file = new File("bear.jpg"); // I have bear.jpg in my working directory  
    FileInputStream fis = new FileInputStream(file);  
    BufferedImage image = ImageIO.read(fis); //reading the image file  

You just need to wrap the file into an FileInputStream and then pass it to read()