ImageIO.read 返回 NULL，没有错误

Question

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");
        }
    }

Thanks in advance for any help.

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.

Answer 1

ImageIO.read(*...) will only load these image types GIF , PNG , JPEG , BMP , and WBMP .

Any other image type will return null without error.

reference:http://docs.oracle.com/javase/tutorial/2d/images/loadimage.html

I do realize this is not a solution to the specific original problem but it is a solution to the question asked.

Answer 2

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()

Answer 3

Try wrap you InputStream into BufferedInputStream:

fis = new FileInputStream(file); ==> new BufferedInputStream(new FileInputStream(file));

Answer 4

使用new File(getClass().getResource("tiles\\\\"+i+".bmp"));

Answer 5

Add the following dependencies:

<dependency>
        <groupId>com.github.jai-imageio</groupId>
        <artifactId>jai-imageio-core</artifactId>
        <version>1.4.0</version>
    </dependency>
    <dependency>
        <groupId>com.github.jai-imageio</groupId>
        <artifactId>jai-imageio-jpeg2000</artifactId>
        <version>1.4.0</version>
    </dependency>