Converting String to Sha-256 Hash

Question

I want to convert a String to a SHA-256 Hash. I am using this code:

String text = "YOLO";
MessageDigest digest = MessageDigest.getInstance("SHA-256");
byte[] hash = digest.digest(text.getBytes("UTF-8"));
System.out.println(hash.toString());

The problem is, when I start the program, it prints

[B@28d93b30

Why is this, and how can solve this?

Thanks in advance,

Fihdi

Answer 1

As others have mentioned, you're using the default toString() method which simply outputs the class name and hashcode

If you want a hex print out of the contents of the byte array try... Hex.encodeHexString(byte[] data) from Apache Commons.

Also How to convert a byte array to a hex string in Java? has some examples for doing this without a library.

Answer 2

要将字节打印为十六进制（而不是该结果，在How do I print my Java object without getting "SomeType@2f92e0f4"? 中进行了解释），只需运行：

System.out.println((new HexBinaryAdapter()).marshal(hash));

Answer 3

In JAVA, arrays do not override Object.toString() . Therefore, hash.toString() does not return a representation of the contents of the array, but rather a representation of the array itself. Apparently, this representation of an array is not very useful. The d efault toString() implementation returns

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

Answer 4

I have also faced this type of issue and then solve in this way.

String text = "YOLO";
MessageDigest digest = MessageDigest.getInstance("SHA-256");
byte[] hash = digest.digest(text.getBytes(StandardCharsets.UTF_8));
String encoded = DatatypeConverter.printHexBinary(hash);        
System.out.println(encoded.toLowerCase());