Get same unique id for same string

Question

Is there a way to find the same integer/long or any digit number equivalent to a given string using java.

eg If i give a string "Java_programming" it should give me always something like "7287272" digit.

The generated digit/number should be unique ie it should always generate "123" for "xyz" not "123" for "abc".

Answer 1

Call the hashCode method of your String object.

Ie :

String t = "Java_programming";
String t2 = "Java_programming";
System.out.println(t.hashCode());
System.out.println(t2.hashCode());

Gives :

748582308
748582308

Using hashCode in this case will meet your requirements (as you formuled it) but be careful, two different String can produce the SAME hashCode value ! (see @Dirk example)

Answer 2

What are your requirements? You could just use a new BigInteger("somestring".toBytes("UTF-8")).toString() to convert the string to a number, but will it do what you want?

Answer 3

Why don't you create a SHA-1 out of the string and use that as a key?

static HashFunction hashFunction = Hashing.sha1();
public static byte[] getHash(final String string) {
  HashCode hashCode = hashFunction.newHasher().putBytes(string.getBytes).hash();
  return hashCode.asBytes();
}

You can then do Bytes.toInt(hash) or Bytes.toLong(hash)

Answer 4

Yes, it is possible. You can use String.hashCode() method on string. Here you find more details how integer returned by this method is created

Answer 5

It depends if you want that 2 different String have to give always 2 different identifiers. String.hashCode() can do what you want, the same string will give always the same ID but 2 different strings can also give the same ID.

If you want a unique identifier you can ie concatenate each byte character value from your string.

Answer 6

First take your string and convert it to a sequence of bytes:

String a = "hello";

byte[] b = a.getBytes();

Now convert the bytes to a numeric representation, using BigInteger

BigInteger c = new BigInteger(b);

Finally, convert the BigInteger back to a string using its toString() method

String d = c.toString();

You are guaranteed to get the same output for the same input, and different outputs for different inputs. You can combine all of these into one step by doing

String d = new BigInteger(a.getBytes()).toString();