图片到字节数组不一致

Question

I'm currently trying to convert a JPEG image from the local java project directory to a byte array to send over a tcp connection.

This is currently how I'm converting my file to a byte array:

BufferedImage imageBuff = ImageIO.read(new File("res/image.jpg"));
ByteArrayOutputStream baos = new ByteArrayOutputStream();
ImageIO.write(imageBuff, "JPEG", baos);
byte[] res = baos.toByteArray();
System.out.println(baos.toByteArray());

I can't seem to find a solid answer as to why this is happening, but every-time I convert it the data is not consistent:

System output:

[B@23f23303
[B@6299504b
[B@417f69df

What exactly is the byte array supposed to look like? It's clearly not working on the other side of the TCP connection for me unfortunately. I would think the output would have the same output each time it tries to convert it, no?

Answer 1

You're calling toString on a byte[] . Arrays don't override toString() , so you're seeing the implementation in Object :

The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `@', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:

 getClass().getName() + '@' + Integer.toHexString(hashCode()) 

So in other words, that has nothing to do with the data within the byte array. Use Arrays.toString(byte[]) to get a string representation which actually looks reasonable - although you may find a hex conversion easier to read.

Answer 2

[B@23f23303 is the String representation of the array object, not the content of the array.

You can use System.out.println(Arrays.toString(baos.toByteArray()));

Answer 3

You're printing out information on the array itself (specifically, the array type [B for byte[] , and then the pointer to the array contents). You probably want to print Arrays.toString(res) .